The routine use of<unk> s is not recommended due to safety concerns, but this approach can be used under medical supervision if there is a clinical rationale for rapid weight loss in obese individuals, as part of a "multi-component weight management strategy" with continuous support and for a maximum of 12 weeks, according to the NICE 2014 guidelines. The US dietary guidelines recommend that<unk> s can be used for weight loss in obese individuals only in limited circumstances and only under supervision by experienced personnel in a medical care setting where the individual can be medically monitored and high-intensity lifestyle intervention can be provided. For the general public,<unk> s are not recommended due to low evidence. As there are considerable risks of starvation with an inadequately composed or supervised<unk> , people attempting these diets must be monitored closely by a physician to prevent complications.<unk> s appear to be more effective than behavioral weight loss programs or other diets, achieving approximately more weight loss at 1 year and greater sustained weight loss after several years. When used in routine care, there is evidence that<unk> s achieve average weight loss at 1 year around or about 4% more weight loss over the short term.<unk> s can achieve higher short-term weight loss compared to other more modest or gradual<unk>  restricted diets, and the maintained long-term weight loss is similar or greater.<unk> s were shown to reduce lean body mass. Combining<unk>  with other obesity therapies yield more effective results in weight loss. Low-calorie and<unk> s may produce faster weight loss within the first 1–2 weeks of starting compared to other diets, but this superficially faster loss is due to glycogen depletion and water loss in the lean body mass and is regained quickly afterward.<unk> s are efficient and recommended for liver fat reduction and weight loss before bariatric surgery. A 2001 review found that<unk>  has no serious harmful effect when done under medical supervision, for periods of 8–16 weeks with an average weight loss of 1.5-2.5 kg/week. However,<unk>  may increase the risk of developing gallstones if the fat content of<unk>  is not sufficient, but data is lacking to know the precise amount of fat that is necessary to avoid gallstones formation. Indeed, dietary fat stimulates gall bladder contraction, thus, if following a fat-free<unk> , the bladder does not empty. Another potential side effect is constipation (depending on the fiber content of the diet).<unk>  were not found to increase food cravings, and on the contrary, appear to reduce food cravings more than low-calorie diets. Previous formulations (medical or commercial) of carbohydrate-free very low<unk>  diets provided 200–800 kcal/day and maintained protein intake, but eliminated any carbohydrate intake and sometimes fat intake as well. These diets subject the body to starvation and produce an average weekly weight loss of . However, the total lack of carbohydrates avoids protein sparing and thus produce a loss of lean muscle mass, as well as other adverse side effects such as increased risks of gout, and electrolyte imbalances, and are thus disadvised. Total diet replacement programs are the modern formulations regulated in Europe and Canada to ensure the recommended daily intake of necessary nutrients, vitamins and electrolyte balance. Compared to older<unk>  formulas, the total diet replacements better preserve lean body mass, reduce known side effects and improve . Unmonitored<unk> s with insufficient macronutrient and mineral intake have the potential to cause an electrolyte imbalance and sudden death via ventricular tachycardia either by starvation or upon refeeding.
Very-low-calorie diet
Low-carbohydrate diet
Low-protein diet
Plant-based diet
Low-fat diet
High-protein diet
Soft diet
Low-FODMAP diet