High-Fiber Diet for Weight Loss
Fiber is a non-digestible carbohydrate found in plant foods only. Animal products, such as meats, poultry, eggs and dairy do not contain dietary fiber. There are two types of fiber: soluble and insoluble. Both are important and offer some of the same (and each offers unique) health benefits. Choosing a high-fiber diet and adding fiber-rich foods to your current diet may offer weight management and even weight loss benefits. Both types of dietary fiber aid in weight control. Dietary fiber enhances satiety or a feeling of fullness.
Fiber-rich foods tend to absorb water and expand (in cooking and in your body) making them filling foods. You are likely to eat less food (in quantity) and less often when you feel satisfied. The Dietary Reference Intake for total fiber is 14 grams (g) per 1,000 calories. This calculates out to an average recommendation of 25 to 30 g daily. The more food you eat, the more dietary fiber you need. Most Americans fall short, averaging 15 g daily. It is important to note that a high-fiber diet alone is not effective for weight loss. You need to cut calories, exercise regularly and, perhaps increase your protein intake.
What are fiber-rich foods?
Foods which are particularly rich in fiber include complex carbohydrates such as whole grains, legumes, seeds, fruits and vegetables. Examples of some of the highest fiber whole grains include oats and oat bran, barley, whole rye, popcorn, wheat bran, amaranth, barley, buckwheat groats and brown rice. Legumes and seeds that provide the most dietary fiber per serving include split peas, lima beans, black beans, garbanzo beans, lentils, white, navy and pinto beans as well as flaxseeds, almonds and sesame seeds. Fruits and vegetables offer dietary fiber as well, though typically not as much as legumes. Some high-fiber choices include acorn squash, cauliflower, broccoli, dark green, leafy veggies, Brussels sprouts, guavas, dried figs and prunes, pears, apples and berries.
How does soluble fiber aid in weight loss?
About 1/3 of the total dietary fiber you consume daily should come in the form of soluble fiber (or a ratio of 1:3 soluble to insoluble fiber). In theory, soluble fiber, also known as viscous fiber, expands in your body as it absorbs water and forms a gel which delays stomach emptying. Thus, it enhances satiety, keeping you from feeling hungry for a longer period of time. Research on the effectiveness of dietary fiber, soluble fiber and fiber supplements on weight loss are inconsistent.
A recent research study, published in the Nutrition Journal in April 2011, compared the effectiveness of a calorie-restricted moderately-high protein diet versus a calorie-restricted high-fiber diet on weight loss in 83 overweight/obese women over eight weeks. The moderately-high protein diet (40 percent calories from each protein and carbohydrate) induced greater weight loss than a relatively-high carbohydrate, fiber rich diet (50 percent of calories from carbohydrate, 20 percent of calories from protein and 35 g total fiber). The women on the moderately-high protein diet lost significantly more weight than on the moderately-high carbohydrate diet (4.5 kg versus 3.3 kg weight lost) and body fat (4.0 kg versus 2.5 kg lost). The amount of soluble fiber, in grams, consumed on the ‘high-fiber’ diet was not specified.
Experts, such as researchers working at the USDA Human Nutrition Research Center on Aging at Tufts University speculate that when energy intake remains constant, consuming an additional 14 g/day fiber for greater than 2 days is associated with a 10% decrease in calorie intake and body weight loss of 1.9 kg over nearly 4 months. However, many research studies looking specifically at soluble fiber intake or supplementation and weight loss have not shown a consistently positive association or cause and effect relationship. It may be a combination of soluble and insoluble fiber that offers the most benefits.
Recently, the focus has centered on the benefits of Beta glucan (β-glucan), a soluble fiber available from oat and barley grains. It has been gaining interest, particularly in the food industry (as an added ingredient) for its beneficial role in insulin resistance, dyslipidemia, high blood pressure and obesity, which continues to be documented.
What are the benefits of eating foods with fiber?
There are well-established benefits of consuming fiber-rich foods, such as lower cholesterol levels, weight control, better blood sugar control and digestive health, particularly alleviating constipation and cardiovascular health. Then there are newly discovered or lesser-known benefits, such as the role dietary fiber plays in slightly altering the immune system’s inflammatory process, according to a July 2008 article published in Today’s Dietitian. Altering the immune system’s inflammatory response may mean a decreased risk of developing cardiovascular disease, diabetes and certain types of cancers.
- El Khoury D et al. Beta glucan: health benefits in obesity and metabolic syndrome. J Nutr Metab. 2012. Epub 2011 Dec 11.
- Saltzman E et al. Effects of a cereal rich in soluble fiber on body composition and dietary compliance during consumption of a hypocaloric diet. J Am Coll Nutr. 2001 Feb; 20(1): 50-7.
- Te Morenga LA et al. Comparison of high protein and high fiber weight-loss diets in women with risk factors for the metabolic syndrome: a randomized trial. Nutr J. 2011 Apr 28; 10:40.
- Palmer S. “The Top Fiber-Rich Foods List.” Today’s Dietitian. July 2008; Vol. 10 No. 7 P. 28.