Dietary strategies for patients with type 2 diabetes in the era of multi-approaches; review and results from the Dietary Intervention Randomized Controlled Trial (DIRECT). Long-term effects of weight loss with a very-low carbohydrate, low saturated fat diet on flow mediated dilatation in patients with type 2 diabetes: A randomised controlled trial. The Canadian Trial of Carbohydrates in Diabetes (CCD), a 1-y controlled trial of low-glycemic-index dietary carbohydrate in type 2 diabetes: no effect on glycated hemoglobin but reduction in C-reactive protein. The effect of a low-carbohydrate, ketogenic diet versus a low-glycemic index diet on glycemic control in type 2 diabetes mellitus A randomised controlled trial of the effect of low fat diet advice on dietary response in insulin independent diabetic women A randomized trial of a low-carbohydrate diet for obesity. A Very Low-Carbohydrate, Low–Saturated Fat Diet for Type 2 Diabetes Management: A Randomized Trial The Effects of Low-Carbohydrate versus Conventional Weight Loss Diets in Severely Obese Adults: One-Year Follow-up of a Randomized Trial One-Year Comparison of a High–Monounsaturated Fat Diet With a High-Carbohydrate Diet in Type 2 Diabetes A Low-Carbohydrate, Ketogenic Diet versus a Low-Fat Diet To Treat Obesity and Hyperlipidemia Comparison of low- and high-carbohydrate diets for type 2 diabetes management: a randomized trial. Comparative Study of the Effects of a 1-Year Dietary Intervention of a Low-Carbohydrate Diet Versus a Low-Fat Diet on Weight and Glycemic Control in Type 2 Diabetes A randomized trial of a low-carbohydrate diet vs orlistat plus a low-fat diet for weight loss. Effect of low-calorie versus low-carbohydrate ketogenic diet in type 2 diabetes. Persistence of Hypertriglyceridemic Effect of Low-Fat High-Carbohydrate Diets in NIDDM Patients Clinical Efficacy of Two Hypocaloric Diets That Vary in Overweight Patients With Type 2 Diabetes Short-term changes in lipoprotein subclasses and C-reactive protein levels of hypertriglyceridemic adults on low-carbohydrate and low-fat diets.
Dietary intervention is recognized as a key component in prevention and management of type 2 diabetes ( T2DM ) and the debate persists : which dietary strategy is most effective . In the Dietary Intervention R and omized Controlled Trial ( DIRECT ) 322 moderately obese participants were r and omized for 2 years to one of three diet groups : low-fat , Mediterranean and low-carbohydrate . Differential effects were observed in the sub-group of patients with T2DM at 24 months : participants r and omized to the Mediterranean diet , which had the highest intake of dietary fibers and unsaturated to saturated fat ratio , achieved greater significant improvements in fasting plasma glucose and insulin levels . Patients who were r and omized to the low-carbohydrate diet , which had the minimal intake of carbohydrates , achieved a significant reduction of hemoglobin A1C . Although improvements were observed in all groups , the low-fat diet was likely to be less beneficial in terms of glycemic control and lipid metabolism . Interpretation of results from different studies on dietary strategies may be complex since there is often no consistency in diet compositions , calorie restriction , intensity of intervention , dietary assessment or extent of adherence in the trial . Nevertheless , it seems that low fat restricted calorie diets are effective for weight loss and are associated with some metabolic benefits ; however , some recent trials have shown that low carbohydrate diets are as efficient in inducing weight loss and in some metabolic measures such as serum triglycerides and HDL-cholesterol may be even superior to low fat diets . When addressing the issue of diet quality rather than quantity applying the glycemic index may have some added benefits . Furthermore special features of the Mediterranean diet have apparent additional favorable effects for patients with T2DM BACKGROUND AND AIMS Very-low carbohydrate diets can improve glycaemic control in patients with type 2 diabetes ( T2DM ) . However , compared to traditional higher carbohydrate , low fat ( HighCHO ) diets , they have been associated with impaired endothelial function ( measured by flow mediated dilatation [ FMD ] ) that is possibly related to saturated fat . This study aim ed to examine the effects of a 12-month hypocaloric very-low carbohydrate , low saturated fat ( LowCHO ) diet compared to an isocaloric HighCHO diet . METHODS One hundred and fifteen obese patients with T2DM ( age:58.4 ± 0.7 [ SEM ] yr , BMI : 34.6 ± 0.4 kg/m(2 ) , HbA1c:7.33 [ 56.3 mmol/mol ] ± 0.10 % ) were r and omised to consume an energy restricted LowCHO diet ( Carb : Pro : Fat : Sat-Fat 14:28:58 : < 10 % energy ; n = 58 ) or isocaloric HighCHO diet ( 53:17:30 : < 10 % ; n = 57 ) whilst undertaking exercise ( 60 min , 3/wk ) . Bodyweight , HbA1c and FMD were assessed . RESULTS Seventy eight participants completed the intervention ( LowCHO = 41 , HighCHO = 37 ) . Both groups experienced similar reductions in weight and HbA1c ( -10.6 ± 0.7 kg , -1.05 ± 0.10 % ; p < 0.001 time , p ≥ 0.48 time × diet ) . FMD did not change ( p = 0.11 time , p = 0.20 time × diet ) . CONCLUSIONS In patients with obesity and T2DM  , HighCHO diet and LowCHO diet have similar effects on endothelial function BACKGROUND The optimal source and amount of dietary carbohydrate for managing type 2 diabetes ( T2DM ) are unknown . OBJECTIVE We aim ed to compare the effects of altering the glycemic index or the amount of carbohydrate on glycated hemoglobin ( HbA1c ) , plasma glucose , lipids , and C-reactive protein ( CRP ) in T2DM patients . DESIGN Subjects with T2DM managed by diet alone ( n=162 ) were r and omly assigned to receive high-carbohydrate , high-glycemic-index ( high-GI ) , high-carbohydrate , low-glycemic-index ( low-GI ) , or low-carbohydrate , high-monounsaturated-fat ( low-CHO ) diets for 1 y. RESULTS The high-GI , low-GI , and low-CHO diets contained , respectively , 47 % , 52 % , and 39 % of energy as carbohydrate and 31 % , 27 % , and 40 % of energy as fat ; they had GIs of 63 , 55 , and 59 , respectively . Body weight and HbA1c did not differ significantly between diets . Fasting glucose was higher ( P=0.041 ) , but 2-h postload glucose was lower ( P=0.010 ) after 12 mo of the low-GI diet . With the low-GI diet , overall mean triacylglycerol was 12 % higher and HDL cholesterol 4 % lower than with the low-CHO diet ( P<0.05 ) , but the difference in the ratio of total to HDL cholesterol disappeared by 6 mo ( time x diet interaction , P=0.044 ) . Overall mean CRP with the low-GI diet , 1.95 mg/L , was 30 % less than that with the high-GI diet , 2.75 mg/L ( P=0.0078 ) ; the concentration with the low-CHO diet , 2.35 mg/L , was intermediate . CONCLUSIONS In subjects with T2DM managed by diet alone with optimal glycemic control , long-term HbA1c was not affected by altering the GI or the amount of dietary carbohydrate . Differences in total : HDL cholesterol among diets had disappeared by 6 mo . However , because of sustained reductions in postpr and ial glucose and CRP , a low-GI diet may be preferred for the dietary management of T2DM Objective Dietary carbohydrate is the major determinant of postpr and ial glucose levels , and several clinical studies have shown that low-carbohydrate diets improve glycemic control . In this study , we tested the hypothesis that a diet lower in carbohydrate would lead to greater improvement in glycemic control over a 24-week period in patients with obesity and type 2 diabetes mellitus . Research design and methods Eighty-four community volunteers with obesity and type 2 diabetes were r and omized to either a low-carbohydrate , ketogenic diet ( < 20 g of carbohydrate daily ; LCKD ) or a low-glycemic , reduced-calorie diet ( 500 kcal/day deficit from weight maintenance diet ; LGID ) . Both groups received group meetings , nutritional supplementation , and an exercise recommendation . The main outcome was glycemic control , measured by hemoglobin A1c . Results Forty-nine ( 58.3 % ) participants completed the study . Both interventions led to improvements in hemoglobin A1c , fasting glucose , fasting insulin , and weight loss . The LCKD group had greater improvements in hemoglobin A1c ( -1.5 % vs. -0.5 % , p = 0.03 ) , body weight ( -11.1 kg vs. -6.9 kg , p = 0.008 ) , and high density lipoprotein cholesterol ( + 5.6 mg/dL vs. 0 mg/dL , p < 0.001 ) compared to the LGID group . Diabetes medications were reduced or eliminated in 95.2 % of LCKD vs. 62 % of LGID participants ( p < 0.01 ) . Conclusion Dietary modification led to improvements in glycemic control and medication reduction/elimination in motivated volunteers with type 2 diabetes . The diet lower in carbohydrate led to greater improvements in glycemic control , and more frequent medication reduction/elimination than the low glycemic index diet . Lifestyle modification using low carbohydrate interventions is effective for improving and reversing type 2 diabetes Summary Type 2 ( insulin independent ) diabetic women were r and omly allocated to receive advice for low fat diets or low carbohydrate diets . By 24 h weighed dietary intakes before and after a mean interval of six months , patients in the low fat group had reduced their fat intake from 41 % to 31 % of total energy , while carbohydrate percentage of total energy intake increased from 38 % to 46 % . Percentage energy intake from fat and carbohydrate in the control group remained unchanged . Body weight fell in both groups , especially for patients in the low fat group who were obese ( weight/height2 ⩾ 28 kg/m2 ) . Mean plasma glucose , HbA1 , and triglycerides were unchanged . Mean plasma total cholesterol fell significantly in the low fat group compared with the controls ( p < 0.001 ) , but there was no significant difference in the small reduction of high density lipoprotein cholesterol observed in both groups . Thus , adherence to low fat diets occurred without deterioration of diabetes and with benefit for weight and total cholesterol BACKGROUND Despite the popularity of the low-carbohydrate , high-protein , high-fat ( Atkins ) diet , no r and omized , controlled trials have evaluated its efficacy . METHODS We conducted a one-year , multicenter , controlled trial involving 63 obese men and women who were r and omly assigned to either a low-carbohydrate , high-protein , high-fat diet or a low-calorie , high-carbohydrate , low-fat ( conventional ) diet . Professional contact was minimal to replicate the approach used by most dieters . RESULTS Subjects on the low-carbohydrate diet had lost more weight than subjects on the conventional diet at 3 months ( mean [ + /-SD ] , -6.8+/-5.0 vs. -2.7+/-3.7 percent of body weight ; P=0.001 ) and 6 months ( -7.0+/-6.5 vs. -3.2+/-5.6 percent of body weight , P=0.02 ) , but the difference at 12 months was not significant ( -4.4+/-6.7 vs. -2.5+/-6.3 percent of body weight , P=0.26 ) . After three months , no significant differences were found between the groups in total or low-density lipoprotein cholesterol concentrations . The increase in high-density lipoprotein cholesterol concentrations and the decrease in triglyceride concentrations were greater among subjects on the low-carbohydrate diet than among those on the conventional diet throughout most of the study . Both diets significantly decreased diastolic blood pressure and the insulin response to an oral glucose load . CONCLUSIONS The low-carbohydrate diet produced a greater weight loss ( absolute difference , approximately 4 percent ) than did the conventional diet for the first six months , but the differences were not significant at one year . The low-carbohydrate diet was associated with a greater improvement in some risk factors for coronary heart disease . Adherence was poor and attrition was high in both groups . Longer and larger studies are required to determine the long-term safety and efficacy of low-carbohydrate , high-protein , high-fat diets OBJECTIVE To comprehensively compare the effects of a very low-carbohydrate , high – unsaturated/low – saturated fat diet ( LC ) with those of a high – unrefined carbohydrate , low-fat diet ( HC ) on glycemic control and cardiovascular disease ( CVD ) risk factors in type 2 diabetes ( T2DM ) . RESEARCH DESIGN AND METHODS Obese adults ( n = 115 , BMI 34.4 ± 4.2 kg/m2 , age 58 ± 7 years ) with T2DM were r and omized to a hypocaloric LC diet ( 14 % carbohydrate [ < 50 g/day ] , 28 % protein , and 58 % fat [ < 10 % saturated fat ] ) or an energy-matched HC diet ( 53 % carbohydrate , 17 % protein , and 30 % fat [ < 10 % saturated fat ] ) combined with structured exercise for 24 weeks . The outcomes measured were as follows : glycosylated hemoglobin ( HbA1c ) , glycemic variability ( GV ; assessed by 48-h continuous glucose monitoring ) , antiglycemic medication changes ( antiglycemic medication effects score [ MES ] ) , and blood lipids and pressure . RESULTS A total of 93 participants completed 24 weeks . Both groups achieved similar completion rates ( LC 79 % , HC 82 % ) and weight loss ( LC −12.0 ± 6.3 kg , HC −11.5 ± 5.5 kg ) ; P ≥ 0.50 . Blood pressure ( −9.8/−7.3 ± 11.6/6.8 mmHg ) , fasting blood glucose ( −1.4 ± 2.3 mmol/L ) , and LDL cholesterol ( −0.3 ± 0.6 mmol/L ) decreased , with no diet effect ( P ≥ 0.10 ) . LC achieved greater reductions in triglycerides ( −0.5 ± 0.5 vs. −0.1 ± 0.5 mmol/L ) , MES ( −0.5 ± 0.5 vs. −0.2 ± 0.5 ) , and GV indices ; P  ≤ 0.03 . LC induced greater HbA1c reductions ( −2.6 ± 1.0 % [ −28.4 ± 10.9 mmol/mol ] vs. −1.9 ± 1.2 % [ −20.8 ± 13.1 mmol/mol ] ; P = 0.002 ) and HDL cholesterol ( HDL-C ) increases ( 0.2 ± 0.3 vs. 0.05 ± 0.2 mmol/L ; P = 0.007 ) in participants with the respective baseline values HbA1c > 7.8 % ( 62 mmol/mol ) and HDL-C < 1.29 mmol/L. CONCLUSIONS Both diets achieved substantial improvements for several clinical glycemic control and CVD risk markers . These improvements and reductions in GV and antiglycemic medication requirements were greatest with the LC compared with HC . This suggests an LC diet with low saturated fat may be an effective dietary approach for T2DM management if effects are sustained beyond 24 weeks Context In 2003 , the authors reported that severely obese adults lost more weight and had better serum lipid patterns after 6 months of a low-carbohydrate diet rather than a conventional low-fat diet . Contribution After 1 year , these same patients still had more favorable triglyceride and high-density lipoprotein cholesterol levels on the low-carbohydrate diet than on the conventional diet . However , weight loss and the other metabolic parameters were similar in the 2 diet groups . Caution s The effect of the modest improvements in high-density lipoprotein cholesterol and triglyceride levels on the development of diabetes and cardiovascular disease is unknown . The Editors The prevalence of obesity and its associated metabolic abnormalities has increased markedly over the past 2 decades ( 1 , 2 ) . Although guidelines to follow a highcomplex carbohydrate , low-fat , energy-deficient diet to achieve weight loss are generally accepted ( 3 ) , considerable public interest has focused on low-carbohydrate diets ( 4 ) . We recently reported that persons with severe obesity lost more weight and had greater improvements in triglyceride levels , insulin sensitivity , and glycemic control after 6 months of a low-carbohydrate diet as compared with a conventional weight loss diet based on calorie and fat restriction ( 5 ) . However , these findings were preliminary because of the short duration of that study ( 6 ) . A simultaneously published study by Foster and colleagues suggested that persons on a low-carbohydrate diet  tended to regain weight by 1 year ( 7 ) . These findings were limited , however , because few participants completed the study and because the study used a self-help approach , which is less effective than direct counseling for maintaining weight loss ( 8) . Foster and colleagues also excluded persons with diabetes , which is highly prevalent in the obese population . During the development of this study , we decided to analyze and report preliminary results at 6 months and final results at 1 year . We thought that the short-term results would be important , given the high-risk nature of our study sample , but that long-term outcomes would provide more information about the sustainability of any diet-related outcomes . We now report our findings 1 year after r and omization to a low-carbohydrate diet versus a low-fat weight loss diet ( conventional diet ) in severely obese adults with a high prevalence of diabetes or the metabolic syndrome . Methods Study Participants The study design has been previously described ( 5 ) . Participants were recruited from the outpatient practice s of the Philadelphia Veterans Affairs Medical Center and included persons 18 years of age and older with a body mass index ( BMI ) of 35 kg/m2 or greater . The exclusion criteria were a serum creatinine level greater than 133 mol/L ( > 1.5 mg/dL ) , hepatic disease , severe life-limiting medical illness , inability to self-monitor glucose levels , or active use of a weight loss program or weight loss medication . Between May 2001 and November 2001 , 132 persons were r and omly assigned to either a low-carbohydrate diet ( n = 64 ) or a conventional diet ( n = 68 ) . The Institutional Review Committee at the Philadelphia Veterans Affairs Medical Center approved the study , and all participants provided written informed consent . Interventions Diet groups met in weekly counseling sessions for 4 weeks , followed by 11 monthly sessions . Participants on the low-carbohydrate diet were instructed only to reduce carbohydrate intake to less than 30 g per day . Participants on the conventional diet were instructed to reduce caloric intake by 500 calories per day , with less than 30 % of calories derived from fat , in accordance with the National Heart , Lung , and Blood Institute guidelines ( 3 ) . Outcome Measures We collected data , including weight ( single calibrated scale , SR Instruments , Inc. , Tonaw and a , New York ) , medical history ( self-reported ) , and blood pressure , at baseline , 6 months , and 1 year . Fasting blood specimens were obtained for glucose , hemoglobin A1c , and serum lipid levels ( Synchron LX20 , Beckman Coulter , Inc. , Fullerton , California ) . Low-density lipoprotein ( LDL ) cholesterol level was calculated by using the Friedewald formula ( 9 ) . We defined the presence of diabetes by a historical fasting blood glucose level greater than 6.94 mmol/L ( > 125 mg/dL ) or use of antidiabetic medications . The metabolic syndrome was considered present if a participant had 3 or more of the following ( 10 ) : central obesity , fasting blood glucose level of 6.11 mmol/L ( 110 mg/dL ) or greater , fasting triglyceride level of 1.70 mmol/L ( 150 mg/dL ) or greater , high-density lipoprotein ( HDL ) cholesterol level less than 1.04 mmol/L ( < 40 mg/dL ) for men or less than 1.30 mmol/L ( < 50 mg/dL ) for women , blood pressure of 130/85 mm Hg or greater , or antihypertensive therapy . We assumed that all participants had central obesity because of the uniform severity of their obesity ( BMI range , 35.0 to 79.4 kg/m2 ) . Serum insulin was measured by radioimmunoassay ( Laboratory Corporation of America Holdings [ LabCorp ] , Burlington , North Carolina ] ) . Insulin resistance in nondiabetic persons was estimated by the quantitative insulin sensitivity check ( QUICK ) index : 1/[(log ( fasting insulin ( U/mL ) ) + ( log fasting glucose(mg/dL ) ) ] . Statistical Analysis Our primary end point was total weight loss at 1 year . Secondary analyses included the change from baseline in serum lipid levels , insulin sensitivity , and glycemic control . We estimated that we would need 100 persons ( 50 per group ) , assuming a 2-sided type I error of 5 % , for the study to have 80 % power to detect a 5-kg greater mean weight loss in the low-carbohydrate group than in the conventional diet group . These calculations were based on an anticipated maximum weight loss by 6 months , with weight stabilization in both diet groups between 6 months and 1 year . To compensate for an anticipated dropout rate of 25 % , we set our enrollment target at 135 persons . R and omization was performed by using a pre-established algorithm generated from a r and om set of numbers that was constructed and held in a separate center and concealed from those enrolling persons during r and omization . We used stratified r and omization , with blocking within strata , to ensure assignment of approximately equal numbers of women , diabetic persons , and severely obese persons ( BMI 40 kg/m2 ) to each study group . Changes in weight , dietary intake , and metabolic data were compared between the 2 diets by r and om-coefficient analysis ( 11 ) . This type of analysis was selected to allow for a variable number of observations for participants and to take into account that the repeated observations of the outcome variables over time for individuals were correlated . The r and om-coefficient analysis model takes these correlations into account by allowing the intercept to vary r and omly among persons . We used a restricted maximum likelihood analysis , which assumed that changes were distributed according to a bivariate normal distribution and that data were missing at r and om . The outcome variables were changes from baseline in weight , dietary macronutrient consumption , and metabolic measurements . For all of these analyses , the covariates included an indicator variable for time ( 6 months and 1 year ) , diet group , and a diet group by time interaction term . This diet group by time interaction term was kept in the model , regardless of its statistical significance ( P = 0.063 for the weight loss analysis ) . Separate analyses to adjust for baseline differences between diet groups were also made by entering the following covariates to each of these models : age ; race ( white or African American ) ; sex ; baseline BMI ; baseline caloric intake ; and the presence or absence of hypertension , use of lipid-lowering therapy , diabetes , active smoking , and sleep apnea ( 12 ) . All variables were assessed for normality before entry into the analyses . Triglyceride , insulin , and glucose levels were skewed and thus were log-transformed before the analyses . Baseline differences between diet groups were compared by chi-square analysis for dichotomous variables and by the unpaired t-test for continuous variables . All P values are 2-sided , and a P value of 0.05 was considered statistically significant . Analyses were performed with SPSS statistical software , version 11.1 ( SPSS , Inc. , Chicago , Illinois ) . Missing Data Of the 132 enrolled persons , follow-up was done at 6 months for 79 persons and at 1 year for 87 persons . For measurements at 6 months , we retrieved weights on an additional 16 persons on the low-carbohydrate diet and 23 persons on the conventional diet ( total , 39 persons at a mean [ SD ] of 6.6 1.2 months ) . For measurements at 1 year , we retrieved weights on 18 persons on the low-carbohydrate diet and 21 persons on the conventional diet ( total , 39 persons at a mean [ SD ] of 13.5 3.2 months ) . Thus , we had 6-month weights on 118 of 132 persons ( 89 % ) and 1-year weights on 126 of 132 persons ( 96 % ) . Of the 18 persons who missed the 6-month visit but returned for the 1-year visit ( 6 in the low-carbohydrate group and 12 in the conventional diet group ) , all but 2 had 6-month weights retrieved from medical records . Of the 6 persons for whom no 1-year weights were available , 2 were in the low-carbohydrate group and 4 in the conventional diet group . The weights retrieved from medical records were obtained on scales that were different from those used for the study and were probably obtained in a nonuniform manner with regard to clothing . We used several approaches to h and le the 45 participants with missing data for diet recall and metabolic measurements . For the primary analysis by r and om-coefficient analysis , we assumed data were missing at r and om . To verify this assumption , we performed sensitivity analyses based on comparisons of baseline characteristics and weight loss differences between those who dropped out and those who completed the study . We also performed 2 additional sensitivity OBJECTIVE —The purpose of this study was to compare the effects of high – monounsaturated fatty acid ( MUFA ) and high-carbohydrate ( CHO ) diets on body weight and glycemic control in men and women with type 2 diabetes . RESEARCH DESIGN AND METHODS —Overweight/obese participants with type 2 diabetes ( n = 124 , age = 56.5 ± 0.8 years , BMI = 35.9 ± 0.3 kg/m2 , and A1C = 7.3 ± 0.1 % ) were r and omly assigned to 1 year of a high-MUFA or high-CHO diet . Anthropometric and metabolic parameters were assessed at baseline and after 4 , 8 , and 12 months of dieting . RESULTS —Baseline characteristics were similar between the treatment groups . The overall retention rate for 1 year was 77 % ( 69 % for the high-MUFA group and 84 % for the high-CHO group ; P = 0.06 ) . Based on food records , both groups had similar energy intake but a significant difference in MUFA intake . Both groups had similar weight loss over 1 year ( −4.0 ± 0.8 vs. −3.8 ± 0.6 kg ) and comparable improvement in body fat , waist circumference , diastolic blood pressure , HDL cholesterol , A1C , and fasting glucose and insulin . There were no differences in these parameters between the groups . A follow-up assessment of a subset of participants ( n = 36 ) was conducted 18 months after completion of the 52-week diet . These participants maintained their weight loss and A1C during the follow-up period . CONCLUSIONS —In individuals with type 2 diabetes  , high-MUFA diets are an alternative to conventional lower-fat , high-CHO diets with comparable beneficial effects on body weight , body composition , cardiovascular risk factors , and glycemic control Context Low-carbohydrate weight reduction diets are popular despite a dearth of data on long-term efficacy and adverse effects . Contribution Community-dwelling hyperlipidemic persons were r and omly assigned to either a low-carbohydrate , ketogenic diet or a low-fat , low-cholesterol , reduced-calorie diet for 24 weeks . Compared to the low-fat group , patients in the low-carbohydrate group lost more weight , had a greater decrease in triglyceride levels , and had higher high-density lipoprotein cholesterol levels . Levels of low-density lipoprotein cholesterol remained stable in both groups . Side effects were more common in the low-cholesterol group but were generally mild . Caution s While the study suggests the efficacy and relative safety of the low-cholesterol diet , the high dropout rate , self-directed adherence to the diet , and relatively short observation period challenge the generalizability of the findings . The Editors As the prevalence of obesity has increased over the past 20 years ( 1 ) , the difficulties faced by overweight patients and their health care practitioners have become apparent . Fewer than 25 % of Americans who attempt to lose weight actually reduce caloric intake and increase exercise as currently recommended ( 2 ) . Persons who successfully lose weight have difficulty maintaining their weight loss ( 3 ) . Therefore , it is not surprising that consumers spend $ 33 billion yearly on weight loss products and services in search of effective therapies ( 2 ) . Because many weight loss interventions are unproven and untested , practitioners often lack information with which to recommend a certain therapy or to monitor a patient once a therapy is chosen . One approach to weight loss that has gained recognition in the face of modest supportive scientific evidence is the low-carbohydrate diet . A popular version of this diet recommends extreme restriction of carbohydrate intake to less than 20 g/d initially ( 4 ) . This level of carbohydrate restriction can induce serum and urinary ketones and weight loss ( 5 , 6 ) . However , until recently , available data on low-carbohydrate diets came from small studies of short duration , most of which were uncontrolled ( 5 , 7 - 10 ) . We examined body weight , body composition , serum lipid levels , and adverse effects over 24 weeks in hyperlipidemic persons who were r and omly assigned to follow a low-carbohydrate , ketogenic diet or a low-fat , low-cholesterol , reduced-calorie diet commonly used to induce weight loss and decrease serum lipid levels . Methods Participants Generally healthy persons were recruited from the community . Inclusion criteria were age 18 to 65 years , body mass index of 30 to 60 kg/m2 , desire to lose weight , elevated lipid levels ( total cholesterol level > 5.17 mmol/L [ > 200 mg/dL ] , low-density lipoprotein [ LDL ] cholesterol level > 3.36 mmol/L [ > 130 mg/dL ] , or triglyceride level > 2.26 mmol/L [ 200 mg/dL ] ) , and no serious medical condition . Exclusion criteria were use of any prescription medication in the previous 2 months ( except for oral contraceptives , estrogen therapy , and stable thyroid medication ) , pregnancy or breastfeeding , use of any weight loss diet or diet pills in the previous 6 months , and baseline ketonuria . All participants provided written informed consent , and the institutional review board of Duke University Health System approved the study . Participants received no monetary incentive . Interventions By using a computer-generated simple r and omization list , participants were allocated to receive the low-carbohydrate diet or low-fat diet . The intervention for both groups included group meetings , diet instruction , and an exercise recommendation . Group meetings took place at an outpatient research clinic twice monthly for 3 months , then monthly for 3 months . These meetings typically lasted 1 hour and consisted of diet instruction , supportive counseling , question naires , and biomedical measurements . During the study , participants selected their own menus and prepared or bought their own meals according to the guidelines presented to them . Participants were encouraged to exercise for 30 minutes at least 3 times weekly , but no formal exercise program or incentives were provided . Low-Carbohydrate Diet Using a popular diet book published by a lay press and additional h and outs , trained research staff instructed participants to restrict intake of carbohydrates to less than 20 g/d ( 4 ) . Participants were permitted unlimited amounts of animal foods ( meat , fowl , fish , and shellfish ) , unlimited eggs , 4 oz of hard cheese , 2 cups of salad vegetables ( such as lettuce , spinach , or celery ) , and 1 cup of low-carbohydrate vegetables ( such as broccoli , cauliflower , or squash ) daily . Participants were encouraged to drink 6 to 8 glasses of water daily . When participants were halfway to their goal body weight ( determined at the week 10 visit with assistance from research personnel ) , they were advised to add approximately 5 g of carbohydrates to their daily intake each week until they reached a level at which body weight was maintained . To simulate the practice of the study sponsor , the low-carbohydrate diet group also received daily nutritional supplements ( multivitamin , essential oils , diet formulation , and chromium picolinate ; for a list of the composition of these supplements , see the Appendix ) ( 6 ) . Low-Fat Diet Using a commonly available booklet and additional h and outs , a registered dietitian instructed participants in a diet consisting of less than 30 % of daily energy intake from fat , less than 10 % of daily energy intake from saturated fat , and less than 300 mg of cholesterol daily ( 11 , 12 ) . The recommended energy intake was 2.1 to 4.2 MJ ( 500 to 1000 kcal ) less than the participant 's calculated energy intake for weight maintenance ( body weight in pounds 10 ) ( 13 ) . Primary Outcome Measure Body weight and body mass index were the primary outcome measures . At each visit , participants were weighed on the same calibrated scale while wearing lightweight clothing and no shoes .  Body mass index was calculated as body weight in kilograms divided by height in meters squared . Secondary Outcome Measures Adherence Adherence to the diet was measured by self-report , food records , and , for the low-carbohydrate diet group , urinary ketone assessment . Diet Composition All participants completed a 24-hour recall of food intake at baseline and take-home food records ( 5 consecutive days , including a weekend ) that were collected at each meeting during the study . Participants were instructed on how to document food intake and were given h and outs with examples of how to complete the records . A sample of participants ( 13 in the low-carbohydrate diet group and 7 in the low-fat diet group ) who completed the study was selected for food record analysis by the research staff on the basis of adequacy of detail in their records . A registered dietitian analyzed the food records by using a nutrition software program ( Nutritionist Five , version 1.6 [ First Data Bank , Inc. , San Bruno , California ] ) . Ketonuria Restriction of dietary intake of carbohydrates to less than 40 g/d typically results in ketonuria that is detectable by dipstick analysis , which can be used to monitor adherence to the low-carbohydrate diet ( 14 , 15 ) . At each return visit , participants provided a fresh urine specimen for analysis . The following semi-quantitative scale was used to categorize ketone content : none , trace ( up to 0.9 mmol/L [ 5 mg/dL ] ) , small ( 0.9 to 6.9 mmol/L [ 5 to 40 mg/dL ] ) , moderate ( 6.9 to 13.8 mmol/L [ 40 to 80 mg/dL ] ) , large80 ( 13.8 to 27.5 mmol/L [ 80 to 160 mg/dL ] ) , and large160 ( > 27.5 mmol/L [ > 160 mg/dL ] ) . Body Composition Body composition was estimated by using bioelectric impedance ( model TBF-300A [ Tanita Corp. , Arlington Heights , Illinois ] ) at approximately the same time of day ( afternoon or evening ) at each return visit . In a subset of 33 participants , the percentage of body fat as measured by bioelectric impedance had excellent correlation with the percentage as measured by dual-energy x-ray absorptiometry ( r = 0.93 [ 95 % CI , 0.87 to 0.97 ] ) . Vital Signs Blood pressure and pulse rate were measured in the nondominant arm by using an automated digital cuff ( model HEM-725C [ Omron Corp. , Vernon Hills , Illinois ] ) after the participant had been sitting for 3 minutes . Two measurements were taken at each visit and averaged for the analysis . Serum Lipids and Lipoproteins Serum specimens for lipid measurement were obtained in the morning after at least 8 hours of fasting at the screening visit and at 8 , 16 , and 24 weeks . Other Metabolic Effects Serum tests for sodium , potassium , chloride , urea nitrogen , creatinine , calcium , phosphorus , total protein , albumin , uric acid , total bilirubin , alanine aminotransferase , aspartate aminotransferase , alkaline phosphatase , thyroid-stimulating hormone , iron , hemoglobin , leukocyte count , and platelet count were obtained at the screening visit and at 8 , 16 , and 24 weeks . The glomerular filtration rate was estimated by using an equation that included age ; sex ; race ; and serum levels of albumin , creatinine , and urea nitrogen ( Modification of Diet in Renal Disease Study equation ) ( 16 ) . Adverse Effects At all return visits , participants completed an open-ended question naire on side effects . At the 20- and 24-week visits , participants completed a checklist of the side effects that were most often mentioned during the study . Statistical Analysis Analyses were performed by using S-PLUS software , version 6.1 ( Insightful Corp. , Seattle , Washington ) , or SAS software , version 8.02 ( SAS Institute , Inc. , Cary , North Carolina ) . For categorical outcomes , groups were compared by using the chi-square test or Fisher exact test , as appropriate . For all primary and secondary continuous outcomes , linear mixed-effects models ( PROC MIXED procedure in SAS software ) that included fixed and r and om effects were used to determine expected mean values at each time point and to test hypotheses of group differences . In most body weight and BACKGROUND Few well-controlled studies have comprehensively examined the effects of very-low-carbohydrate diets on  type 2 diabetes ( T2D ) . OBJECTIVE We compared the effects of a very-low-carbohydrate , high-unsaturated fat , low-saturated fat ( LC ) diet with a high-carbohydrate , low-fat ( HC ) diet on glycemic control and cardiovascular disease risk factors in T2D after 52 wk . DESIGN In this r and omized controlled trial that was conducted in an outpatient research clinic , 115 obese adults with T2D [ mean ± SD age : 58 ± 7 y ; body mass index ( in kg/m(2 ) ) : 34.6 ± 4.3 ; glycated hemoglobin ( HbA1c ) : 7.3 ± 1.1 % ; duration of diabetes : 8 ± 6 y ] were r and omly assigned to consume either a hypocaloric LC diet [ 14 % of energy as carbohydrate ( carbohydrate < 50 g/d ) , 28 % of energy as protein , and 58 % of energy as fat ( < 10 % saturated fat ) ] or an energy-matched HC diet [ 53 % of energy as carbohydrate , 17 % of energy as protein , and 30 % of energy as fat ( < 10 % saturated fat ) ] combined with supervised aerobic and resistance exercise ( 60 min ; 3 d/wk ) . Outcomes were glycemic control assessed with use of measurements of HbA1c , fasting blood glucose , glycemic variability assessed with use of 48-h continuous glucose monitoring , diabetes medication , weight , blood pressure , and lipids assessed at baseline , 24 , and 52 wk . RESULTS Both groups achieved similar completion rates ( LC diet : 71 % ; HC diet : 65 % ) and mean ( 95 % CI ) reductions in weight [ LC diet : -9.8 kg ( -11.7 , -7.9 kg ) ; HC diet : -10.1 kg ( -12.0 , -8.2 kg ) ] , blood pressure [ LC diet : -7.1 ( -10.6 , -3.7)/-6.2 ( -8.2 , -4.1 ) mm Hg ; HC diet : -5.8 ( -9.4 , -2.2)/-6.4 ( -8.4 , -4.3 ) mm Hg ] , HbA1c [ LC diet : -1.0 % ( -1.2 % , -0.7 % ) ; HC diet : -1.0 % ( -1.3 % , -0.8 % ) ] , fasting glucose [ LC diet : -0.7 mmol/L ( -1.3 , -0.1 mmol/L ) ; HC diet : -1.5 mmol/L ( -2.1 , -0.8 mmol/L ) ] , and LDL cholesterol [ LC diet : -0.1 mmol/L ( -0.3 , 0.1 mmol/L ) ; HC diet : -0.2 mmol/L ( -0.4 , 0.03 mmol/L ) ] ( P-diet effect ≥ 0.10 ) . Compared with the HC-diet group , the LC-diet group achieved greater mean ( 95 % CI ) reductions in the diabetes medication score [ LC diet : -0.5 arbitrary units ( -0.7 , -0.4 arbitrary units ) ; HC diet : -0.2 arbitrary units ( -0.4 , -0.06 arbitrary units ) ; P = 0.02 ] , glycemic variability assessed by measuring the continuous overall net glycemic action-1 [ LC diet : -0.5 mmol/L ( -0.6 , -0.3 mmol/L ) ; HC diet : -0.05 mmol/L ( -0.2 , -0.1 mmol/L ) ; P = 0.003 ] , and triglycerides [ LC diet : -0.4 mmol/L ( -0.5 , -0.2 mmol/L ) ; HC diet : -0.01 mmol/L ( -0.2 , 0.2 mmol/L ) ; P = 0.001 ] and greater mean ( 95 % CI ) increases in HDL cholesterol [ LC diet : 0.1 mmol/L ( 0.1 , 0.2 mmol/L ) ; HC diet : 0.06 mmol/L ( -0.01 , 0.1 mmol/L ) ; P = 0.002 ] . CONCLUSIONS Both diets achieved substantial weight loss and reduced HbA1c and fasting glucose . The LC diet , which was high in unsaturated fat and low in saturated fat , achieved greater improvements in the lipid profile , blood glucose stability , and reductions in diabetes medication requirements , suggesting an effective strategy for the optimization of T2D management . This trial was registered at www.anzctr.org.au as ACTRN12612000369820 OBJECTIVE To compare the effects of a 1-year intervention with a low-carbohydrate and a low-fat diet on weight loss and glycemic control in patients with type 2 diabetes . RESEARCH DESIGN AND METHODS This study is a r and omized clinical trial of 105 overweight adults with type 2 diabetes . Primary outcomes were weight and A1C . Secondary outcomes included blood pressure and lipids . Outcome measures were obtained at 3 , 6 , and 12 months . RESULTS The greatest reduction in weight and A1C occurred within the first 3 months . Weight loss occurred faster in the low-carbohydrate group than in the low-fat group ( P = 0.005 ) , but at 1 year a similar 3.4 % weight reduction was seen in both dietary groups . There was no significant change in A1C in either group at 1 year . There was no change in blood pressure , but a greater increase in HDL was observed in the low-carbohydrate group ( P = 0.002 ) . CONCLUSIONS Among patients with type 2 diabetes , after 1 year a low-carbohydrate diet had effects on weight and A1C similar to those seen with a low-fat diet . There was no significant effect on blood pressure , but the low-carbohydrate diet produced a greater increase in HDL cholesterol BACKGROUND Two potent weight loss therapies , a low-carbohydrate , ketogenic diet ( LCKD ) and orlistat therapy combined with a low-fat diet ( O + LFD ) , are available to the public but , to our knowledge , have never been compared . METHODS Overweight or obese out patients ( n = 146 ) from the Department of Veterans Affairs primary care clinics in Durham , North Carolina , were r and omized to either LCKD instruction ( initially , < 20 g of carbohydrate daily ) or orlistat therapy , 120 mg orally 3 times daily , plus low-fat diet instruction ( < 30 % energy from fat , 500 - 1000 kcal/d deficit ) delivered at group meetings over 48 weeks . Main outcome measures were body weight , blood pressure , fasting serum lipid , and glycemic parameters . RESULTS The mean age was 52 years and mean body mass index was 39.3 ( calculated as weight in kilograms divided by height in meters squared ) ; 72 % were men , 55 % were black , and 32 % had type 2 diabetes mellitus . Of the study participants , 57 of the LCKD group ( 79 % ) and 65 of the O + LFD group ( 88 % ) completed measurements at 48 weeks . Weight loss was similar for the LCKD ( expected mean change , -9.5 % ) and the O + LFD ( -8.5 % ) ( P = .60 for comparison ) groups . The LCKD had a more beneficial impact than O + LFD on systolic ( -5.9 vs 1.5 mm Hg ) and diastolic ( -4.5 vs 0.4 mm Hg ) blood pressures ( P < .001 for both comparisons ) . High-density lipoprotein cholesterol and triglyceride levels improved similarly within both groups . Low-density lipoprotein cholesterol levels improved within the O + LFD group only , whereas glucose , insulin , and hemoglobin A(1c ) levels improved within the LCKD group only ; comparisons between groups , however , were not statistically significant . CONCLUSION In a sample of medical out patients , an LCKD led to similar improvements as O + LFD for weight , serum lipid , and glycemic parameters and was more effective for lowering blood pressure . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00108524 OBJECTIVE Effective diabetic management requires reasonable weight control . Previous studies from our laboratory have shown the beneficial effects of a low-carbohydrate ketogenic diet ( LCKD ) in patients with type 2 diabetes after its long term administration . Furthermore , it favorably alters the cardiac risk factors even in hyperlipidemic obese subjects . These studies have indicated that , in addition to decreasing body weight and improving glycemia , LCKD can be effective in decreasing antidiabetic medication dosage . Similar to the LCKD , the conventional low-calorie , high nutritional value diet is also used for weight loss . The purpose of this study was to underst and the beneficial effects of LCKD compared with the low-calorie diet ( LCD ) in improving glycemia . METHODS Three hundred and sixty-three overweight and obese participants were recruited from the Al-Shaab Clinic for a 24-wk diet intervention trial ; 102 of them had type 2 diabetes . The participants were advised to choose LCD or LDKD , depending on their preference . Body weight , body mass index , changes in waist circumference , blood glucose level , changes in hemoglobin and glycosylated hemoglobin , total cholesterol , low-density lipoprotein cholesterol , high-density lipoprotein cholesterol , triglycerides , uric acid , urea and creatinine were determined before and at 4 , 8 , 12 , 16 , 20 , and 24 wk after the administration of the LCD or LCKD . The initial dose of some antidiabetic medications was decreased to half and some were discontinued at the beginning of the dietary program in the LCKD group . Dietary counseling and further medication adjustment were done on a biweekly basis . RESULTS The LCD and LCKD had beneficial effects on all the parameters examined . Interestingly , these changes were more significant in subjects who were on the LCKD as compared with those on the LCD . Changes in the level of creatinine were not statistically significant . CONCLUSION This study shows the beneficial effects of a ketogenic diet over the conventional LCD in obese diabetic subjects . The ketogenic diet appears to improve glycemic control . Therefore , diabetic patients on a ketogenic diet should be under strict medical supervision because the LCKD can significantly lower blood glucose levels Although low-fat high-carbohydrate diets are recommended for patients with non-insulin-dependent diabetes mellitus ( NIDDM ) in an effort to reduce the risk of coronary artery disease ( CAD ) , the results of short-term studies have shown that these diets can lead to changes in carbohydrate and lipid metabolism associated with an increased risk of CAD . This study has extended these earlier observations by determining the metabolic effects of such diets over a longer period in these patients . The comparison diets contained either 40 or 60 % of the total calories as carbohydrates , with reciprocal changes in fat content from 40 to 20 % consumed in r and om order for 6 wk in a crossover experimental design . The ratio of polyunsaturated to saturated fat and the total cholesterol intake were held constant in the two diets . Plasma glucose and insulin concentrations were significantly ( P < .001 ) elevated throughout the day when patients consumed the 60 % carbohydrate diet , and 24-h urinary glucose excretion more than doubled ( 0.8 vs. 1.8 mol/24 h ) . Fasting plasma total and very-low-density lipoprotein ( VLDL ) triglyceride ( TG ) concentrations increased by 30 % ( P < .001 ) after 1 wk on the 60 % carbohydrate diet , and the magnitude of carbohydrate-induced hypertriglyceridemia persisted unchanged throughout the 6-wk study period . Total plasma cholesterol concentrations were similar after both diets . However , VLDL cholesterol ( VLDL-chol ) was significantly increased , whereas both low-density lipoprotein ( LDL- ) and high-density lipoprotein ( HDL- ) chol concentrations were significantly decreasedafter consumption of the 60 % carbohydrate diet . Consequently , neither total-chol-to-HDL-chol nor LDL-chol-to-HDL-chol ratios changed . The results of this study indicate that high-carbohydrate diets lead to several changes in carbohydrate and lipid metabolism in patients with NIDDM that could lead to an increased risk of CAD , and these effects persist for > 6 wk . Given these results , it seems reasonable to suggest that the routine recommendation of low-fat high-carbohydrate diets for patients with NIDDM be reconsidered Approximately 80 % of patients with type 2 diabetes are overweight/obese ( 1 ) , and weight loss is the mainstay of treatment for these individuals . However , there is growing controversy as to whether reduced-fat or reduced-carbohydrate diets are best suited for this purpose , and results ( 2–8 ) in nondiabetic subjects suggest that lower carbohydrate diets are similarly or more efficacious in improving weight , triglycerides , and HDL cholesterol . There are no published r and omized studies evaluating the role of dietary macronutrients with respect to weight loss and cardiovascular risk improvement in patients with type 2 diabetes . Thus , we r and omized diet-treated patients with type 2 diabetes to hypocaloric diets , moderately restricted in either carbohydrate or fat , to determine whether weight loss or metabolic improvement differed as a function of macronutrient composition . A total of 29 patients with diet-treated type 2 diabetes were recruited from the San Francisco Bay area . All subjects gave written informed consent . Inclusion criteria included BMI 27–36 kg/m2 , fasting plasma glucose concentration 7.2–8.3 mmol/l , no use of antihyperglycemic medications , and stable weight for 3 months . Subjects on anti-hypertensive or cholesterol-lowering drugs or aspirin were allowed to continue their medications . Insulin-mediated glucose uptake was quantified by a modification ( 9 ) of the insulin suppression test as originally described ( 10 ) and vali date d ( 11 ) . In this test , a 180-min infusion of somatostatin ( 0.27 μg/m2 per min ) , insulin ( 25 mU/m2 per min ) , Diets design ed to promote weight loss and improve atherogenic lipid profiles traditionally include a reduction in total fat and , in particular , saturated fats . This study was design ed to test the efficacy of a low-fat diet vs a carbohydrate (CHO)-restricted ( low-CHO ) diet in hypertriglyceridemic patients on lipid profile , weight loss , high-sensitivity C-reactive protein ( hs-CRP ) , and satiety .  Twenty-eight hypertriglyceridemic subjects ( based on fasting triacylglycerol [ TG ] levels exceeding 1.69 mmol/L ) were r and omized to either the  low-CHO or low-fat diet  for 8 weeks . Fasting bloods were acquired at weeks 0 and 8 and analyzed for lipids and hs-CRP . Body weight and other anthropometric measures were also obtained . Three r and om 24-hour food recalls were used to assess compliance during the trial and 2 recalls before r and omization to permit individualized dietary education . A significant time-by-treatment interaction was observed ( P = .045 ) , wherein the small low-density lipoprotein cholesterol concentrations were reduced by 46 % in the low-CHO-assigned subjects and increased by 36 % for those assigned the low-fat plan . The observed decrease in TG ( 18 % ) among low-CHO subjects , in contrast to the 4 % increase for low-fat group , was not significant , nor were there significant differences in hs-CRP , overall dietary compliance , satiety , or the magnitude of body weight loss between groups ( low-CHO group , -3.8 % vs low-fat group , -1.6 % ) . Favorable reductions in small low-density lipoprotein concentrations after 8 weeks suggest that a moderately restricted carbohydrate diet ( 20 % CHO as energy ) can promote a less atherogenic lipid profile when compared to the low-fat diet
Based on the evidence review ed , low-CHO and very-low-CHO diets are not superior to other dietary approaches for weight loss .
These diets may have advantages related to appetite control , triglyceride reduction , and reduction in the use of medication in T2D management .
The evidence review ed showed mixed effects on low-density lipoprotein cholesterol levels with some studies showing an increase .
There was no clear evidence for advantages regarding effects on other cardiometabolic risk markers .
Historically , low-carbohydrate ( CHO ) and very-low-CHO diets have been used for weight loss .
Recently , these diets have been promoted for type 2 diabetes ( T2D ) management .
This scientific statement provides a comprehensive review of the current evidence base available from recent systematic review s and meta-analyses on the effects of low-CHO and very-low-CHO diets on body weight , lipoprotein lipids , glycemic control , and other cardiometabolic risk factors .