The study involved 240 obese men and women between the ages of 21 and 70 years. Half of the individuals were randomly assigned to a very specific heart-healthy diet based on the American Heart Association guidelines and given a personalized daily calorie goal. In addition to limiting sugar, saturated fat, and other nutrients, these participants were encouraged to eat more fruits, vegetables, whole grains, and fiber, choose lean animal proteins and plant proteins, and enjoy fish at least twice weekly. The second group was given just one simple goal: to eat at least 30 grams of fiber daily. Both groups received extensive nutrition counseling from registered dietitians, including two one-on-one sessions and 12 group sessions.
At the start of the study, participants in both groups were eating on average 19 grams of fiber per day, falling short of the recommended intake of 21 to 25 grams daily for women and 30 to 38 grams for men. After one year on the diet, the high-fiber group were eating about 5 extra grams of fiber per day. The heart-healthy group increased their fiber intake by about 3 grams three months into the study, but then drifted back to their baseline level.
The weight loss in both groups was modest, even compared to other studies that assess the effects of diet changes alone on body weight. Since both groups achieved similar results, it's possible that the counseling sessions had a greater impact on participants' success than the assigned diet plan.
Still, it's encouraging to see that one simple, positive message — eat more fiber — may help people halt gradual weight gain and even reverse the trend. On the other hand, previous studies have found that simply eating more fruits and vegetables does not have a meaningful impact on body weight.
Unfortunately, neither diet helped people lower their cholesterol or fasting glucose levels. This may have to do with the types of foods the participants were eating to bump up their fiber intake. The high-fiber group didn't increase their intake of fruits and vegetables, and only about 1.5 grams of their additional 5-gram intake came from cereal grains. It's possible that participants were eating more fiber-fortified foods like breakfast cereals, cookies, crackers, and bars in an attempt to reach their daily goal. Most of the research demonstrating the health benefits of fiber has studied exclusively intact fiber from whole food sources like whole grains, beans, vegetables, and fruits, and it isn't clear that isolated fibers like inulin and polydextrose added to packaged foods offer the same advantages.
If you'd like to increase your fiber intake, either in an effort to manage your weight or improve overall health, I strongly recommend targeting at least 25 grams from whole food sources. Here are some of the best sources of fiber to help you hit your target and maximize the wellness payoff.
- Beans and lentils: These plant-based proteins are also fiber powerhouses, supplying 6 to 10 grams per 1/2 cup serving. Enjoying one cup several days per week is one of the smartest ways to increase your daily fiber intake. Eating beans regularly has been shown to lower blood pressure, cholesterol, and blood sugar, so including them at more meals can dramatically boost your health profile.
- Whole grains: Most intact, whole-kernel grains supply 1.5 to 5 grams fiber per 1/2 cup serving of cooked grains. The best of the best (in terms of fiber tallies) include bulgur, farro (and other wheat berries), quinoa, and amaranth, but other favorites like oats are still great choices.
- Seeds and nuts: Chia seeds are especially rich at 5 grams of fiber per tablespoon, but ground flax, sunflower, sesame, pumpkin, and hemp can add to your daily total, too. In the nut category, almonds, pistachios, pecans, and hazelnuts supply the most fiber.
- Vegetables: To boost your fiber intake, add more leafy greens, broccoli, sweet or white potatoes with skin, Brussels sprouts, winter squash (like butternut), and parsnips.
- Fruits: Get your sweet fix from fiber-rich berries, pears, apples, bananas, oranges, and mango.
While eating more fiber is a terrific goal to strive for, I still think it's important to look at the whole picture and focus on other aspects of a healthy diet, like eating more plant-based meals, limiting sugar and refined grains, and emphasizing healthy unsaturated fats from plant oils, nuts, seeds, avocado, and fish. Fortunately, eating more high-fiber foods can help you make progress in all of these areas.
If you're not currently eating a lot of fiber, increase your intake gradually over the course of several weeks to help keep gas and discomfort to a minimum. Drink plenty of water throughout the day, chew slowly and thoroughly, and be patient with your body. It takes time for your gastrointestinal system and gut flora to adjust, but the changes are all for the better.
Important: The views and opinions expressed in this article are those of the author and not Everyday Health.