Elsevier

Nutrition

Volume 21, Issue 3, March 2005, Pages 411-418
Nutrition

Review article
Dietary fiber and body weight

https://doi.org/10.1016/j.nut.2004.08.018Get rights and content

Abstract

Objective

This review provides an update of recent studies of dietary fiber and weight and includes a discussion of potential mechanisms of how dietary fiber can aid weight loss and weight maintenance.

Methods

Human studies published on dietary fiber and body weight were reviewed and summarized. Dietary fiber content of popular low-carbohydrate diets were calculated and are presented.

Results

Epidemiologic support that dietary fiber intake prevents obesity is strong. Fiber intake is inversely associated with body weight and body fat. In addition, fiber intake is inversely associated with body mass index at all levels of fat intake after adjusting for confounding factors. Results from intervention studies are more mixed, although the addition of dietary fiber generally decreases food intake and, hence, body weight. Many mechanisms have been suggested for how dietary fiber aids in weight management, including promoting satiation, decreasing absorption of macronutrients, and altering secretion of gut hormones.

Conclusion

The average fiber intake of adults in the United States is less than half recommended levels and is lower still among those who follow currently popular low-carbohydrate diets, such as Atkins and South Beach. Increasing consumption of dietary fiber with fruits, vegetables, whole grains, and legumes across the life cycle is a critical step in stemming the epidemic of obesity found in developed countries. The addition of functional fiber to weight-loss diets should also be considered as a tool to improve success.

Introduction

The increasing prevalence of obesity in the United States population and associated morbidity compels us to develop dietary strategies to combat the problem. Although it is well known that excess calorie intake is the primary dietary cause, alterations in food patterns or nutrients must be considered. Dietary guidance universally recommends diets higher in fiber for health promotion and disease prevention, but there are inconsistencies in the literature on the relation of dietary fiber to body weight. The first goal of this review is to describe the challenges in measuring dietary fiber intake in studies and describe recent developments in dietary fiber definitions and recommendations. Second, epidemiologic studies on the role of fiber in weight maintenance will be summarized. Third, intervention studies on dietary fiber and weight loss will be presented. Fourth, potential mechanisms for how dietary fiber may aid weight loss will be described. The current obesity epidemic in developed countries demands that we design diets to improve weight loss and maintenance. In addition, the popularity of low-carbohydrate diets that are low in dietary fiber must be considered in this discussion.

Section snippets

What is dietary fiber?

Examining the relation between dietary fiber intake and body weight is difficult because we struggle to define dietary fiber and agree on recommended intake levels. New definitions for dietary fiber and recommendations for fiber intake were published as dietary reference intakes [1]. Dietary fiber consists of non-digestible carbohydrates and lignin that are intrinsic and intact in plants. Functional fiber consists of isolated, non-digestible carbohydrates that have beneficial physiologic

Fiber levels of popular weight-loss diets

In general, dietary fiber intakes are linked to total food intake and thus calorie intake. Fiber recommendations published in the dietary reference intakes are related to calorie intake and explain why the recommendation for men, 38 g/d, is higher than the recommendation for women, 25 g/d. Previous recommendations suggested that Americans consume 10 to 13 g of fiber per 1000 kcal consumed [7].

The fiber levels of popular diets have been reported by Anderson et al. [8]. When the dietary fiber

Epidemiologic studies on dietary fiber and weight

The “fiber hypothesis” suggests that consumption of unrefined, high-fiber carbohydrate-based foods protects against industrialized diseases such as diabetes, cancer, heart disease, and obesity. These traditional diets are high in dietary fiber and low in dietary fat, making it difficult to separate out these effects. Roberts and Heyman [9] suggested that that too often there is an overemphasis on dietary fat. Dietary factors less frequently examined for their role in obesity include fiber,

Fiber and body mass index

In cross-sectional observational studies, fiber intake is inversely associated with body weight [12], [13] and body fat [14]. In the Seven Countries Study, dietary fiber was significantly inversely associated with subscapular skinfold thickness [15]. Few studies have compared different fiber types and their association with body weight. In a longitudinal study, fiber intake was inversely associated with body mass index at all levels of fat intake after adjustment for lifestyle factors and other

Fiber and weight loss

Many intervention studies have investigated whether dietary fiber intake assists in weight loss and results have been inconsistent. Birketvedt et al. [19] found that the addition of dietary fiber to a low-calorie diet significantly improved weight loss, with the placebo group losing 5.8 kg and the fiber-supplemented group losing 8.0 kg. When postmenopausal women consumed higher-fiber diets as part of a study of very low-fat diets and weight loss, the higher-fiber diets were associated with

Does dietary fiber promote satiation?

Although emphasis has been placed on specific effects that can be detected as statistically significant when a particular fiber source is consumed, dietary fiber has many subtle, less easily quantifiable effects that are beneficial. A fiber-rich meal is processed more slowly and nutrient absorption occurs over a longer period [29]. Further, a diet of foods that provide adequate fiber is usually less energy dense and larger in volume than a low-fiber diet that may limit spontaneous intake of

Does dietary fiber alter glycemic or insulin response?

When viscous fibers are isolated and thereby concentrated, their effects on digestion are frequently easier to detect; when these types of fibers are added to a diet, the rate of glucose appearance in the blood is slowed, and insulin secretion is subsequently decreased. These beneficial effects on blood glucose and insulin concentrations are most evident in individuals who have diabetes mellitus. In healthy individuals, the rapid insulin secretion that causes rapid removal of glucose from the

Does dietary fiber decrease absorption of macronutrients and thus energy?

Theoretically, if dietary fiber could block or limit the absorption of macronutrients, it could aid in weight control. Even a small change in absorption could have long-term significance in weight maintenance. Few studies have been conducted in this area because of the need to collect fecal samples and measure fecal energy, fat, protein, or carbohydrate. Gades and Stern [37] measured the ability of a commercially available chitosan supplement on fecal fat excretion in men. Chitosan-based

Does dietary fiber affect gastric emptying?

Dietary fiber affects gastrointestinal physiology and functions including delaying gastric emptying [38]. Consumption of viscous fibers delays gastric emptying, which may cause an extended feeling of fullness [39] and may delay absorption of glucose and other nutrients. Yao and Roberts [40] summarized the effect of an increase in energy density on the rate of gastric emptying in humans and consistently found that high-fiber diets slowed gastric emptying. Although the exact mechanism whereby

Does dietary fiber affect secretion of gut hormones, including cholecystokinin, independently of glycemic response?

Beyond the effects of dietary fiber on postprandial glucose, insulin, and satiety discussed above, dietary fibers alter responses and actions of the gut hormones gastric inhibitory peptide [41], glucagon-like peptide-1 [42], and cholecystokinin (CCK). CCK is a peptide hormone and a neurotransmitter secreted by cells in the upper part of the small intestine after ingestion of food. CCK regulates gut motility, gallbladder contraction, and pancreatic enzyme secretion. CCK may mediate postprandial

Does dietary fiber decrease food intake at a later eating occasion?

Fiber may have the added benefit of helping consumers decrease food intake throughout the day. However, results of trials examining this possibility have been conflicting. In general, large intakes of dietary fiber at breakfast are associated with less food intake at a lunch. Burley et al. [51] found that 29 g of sugar beet fiber resulted in 14% less energy consumption at lunch. Levine et al. [52] also found less food intake at lunch when a high-fiber breakfast cereal was consumed earlier in

Summary

Long-term insufficient intake of dietary fiber represents a challenge for the dietetics professional that can be met with enthusiastic recommendations for a healthy dietary pattern. Modest increases in intakes of fruits, vegetables, legumes, and whole and high-fiber grain products would bring the majority of the North American adult population close to the recommended ranges of dietary fiber intake of 25 g/d for women and 38 g/d for men. In addition, a higher-fiber intake provided by foods is

References (54)

  • S. Holt et al.

    Relationship of satiety to postprandial glycaemic, insulin and cholecystokinin responses

    Appetite

    (1992)
  • I. Bourdon et al.

    Beans, as a source of dietary fiber, increase cholecystokinin and apolipoprotein B48 response to test meals in men

    J Nutr

    (2001)
  • S.H.A. Holt et al.

    The effects of equal-energy portions of different breads on blood glucose levels, feelings of fullness and subsequent food intake

    J Am Diet Assoc

    (2001)
  • B. Burton-Freeman et al.

    Plasma cholecystokinin is associated with subjective measures of satiety in women

    Am J Clin Nutr

    (2002)
  • I. Bourdon et al.

    Postprandial lipid, glucose, insulin, and cholecystokinin responses in men fed barley pasta enriched with β-glucan

    Am J Clin Nutr

    (1999)
  • D. Geleva et al.

    A solubilized cellulose fiber decreases peak postprandial cholecystokinin concentrations after a liquid mixed meal in hypercholesterolemic men and women

    J Nutr

    (2003)
  • J.A. Marlett et al.

    Position of the American Dietetic Associationhealth implications of dietary fiber

    J Am Diet Assoc

    (2002)
  • Dietary reference intakes. Energy, carbohydrates, fiber, fat, fatty acids, cholesterol, protein and amino acids

    (2002)
  • Dietary reference intakes. Proposed definition of dietary fiber

    (2001)
  • D.J.A. Jenkins et al.

    Physiological effects of resistant starches on fecal bulk, short chain fatty acids, blood lipids and glycemic index

    J Am Coll Nutr

    (1998)
  • J.H. Cummings

    The effect of dietary fiber on fecal weight and composition

  • S. Pilch

    Physiological effects and health consequences of dietary fiber

    (1987)
  • J.W. Anderson et al.

    Health advantages and disadvantages of weight-reducing dietsa computer analysis and critical review

    J Am Coll Nutr

    (2000)
  • L. Lissner et al.

    Swedish obese subjects (SOS)an obesity intervention study with a nutritional perspective

    Eur J Clin Nutr

    (1998)
  • S. Kimm

    The role of dietary fiber in the development and treatment of childhood obesity

    Pediatrics

    (1995)
  • M. Alfieri et al.

    Fiber intake of normal weight, moderately obese and severely obese subjects

    Obesity Res

    (1995)
  • P.M. Appleby et al.

    Low body mass index in non-meat eatersthe possible roles of animal fat, dietary fibre and alcohol

    Int J Obesity Relat Metab Disord

    (1998)
  • Cited by (754)

    View all citing articles on Scopus

    Novartis Consumer Health supported the preparation of this review with an educational grant.

    View full text