Eat Fiber: One Simple Message for Weight Loss

Review

“Single-Component Versus Multicomponent Dietary Goals for the Metabolic Syndrome”

This study was a randomized, controlled trial of 240 adults with metabolic syndrome who were assigned to follow either the single-component dietary recommendation of increased fiber consumption (≥30g/d), or the multi-component American Heart Association (AHA) dietary guidelines. The primary outcome measure was weight loss at 12 months.

Study Results

The mean age and BMI of participants were 52 years and 35 kg/m², respectively. The 1-year completion rate was 89%, with 12 patients having dropped out of the high-fiber diet group, and 15 having dropped out of the AHA diet group. There were no meaningful differences found between the two groups for baseline characteristics.

Weight loss was statistically significant in both groups. Weight loss in the high fiber group at 12 months was -2.1 kg, while weight loss in the AHA group was -2.7 kg at 12 months. The mean difference between the two groups was not significant (CI, -0.5 to 1.7 kg). Reduction in waist circumference was greater in the AHA diet group by a statistically significant mean of 0.5 inches (CI, 0.1 to 1.0 inches).

Total caloric intake at 12 months in the high fiber group was decreased by 200 kcal/d, while the AHA diet group demonstrated a decrease of 464.6 kcal/d. The mean difference between the two groups was 264.6 kcal/d (CI, 104.4 to 427.7kcal/d).

Conclusion

Statistically significant weight loss was seen in both groups at 12 months, with no statistically significant difference between the two groups. Total caloric intake and waist circumference were decreased in both groups as well with a greater reduction seen in the AHA group.

Discussion

Previous studies have demonstrated weight loss and improved metabolic health can be achieved through strict adherence to either the AHA dietary guidelines or through maintaining a high fiber diet. This study supports this claim, having demonstrated weight loss with both diets, and without a significant difference in weight loss between the two groups.

Although an intergroup difference in weight loss was not observed, the AHA dietary guidelines are multi-component, more complicated to adhere to, and restrictive in nature, while the high fiber guidelines are single component and permissive. The authors did note this study is limited because the majority of its participants were well-educated white women, and their baseline fiber intake and dietary quality were already greater than the national average. Thus, the generalizability of these results can be questioned.

It’s reasonable to draw from this study that following a single-component high fiber diet may be easier for patients to focus on and adhere to across all demographics. Additionally, it has been shown altering this one dietary component—eating 30 or more grams of fiber per day-- promotes overall nutritional health (decreased risks of coronary heart disease and type 2 diabetes and lower rates of some cancers) in a simple, permissive manner.

There is conflicting data on the use of fiber supplements as a means for increasing daily fiber consumption to facilitate weight loss. Although some studies have shown reductions in bodyweight and caloric consumption in patients using fiber supplements, this has not been consistently shown. The benefits beyond weight loss (e.g. improved nutrition, cardiovascular health, reduced risk of certain cancers, etc.) come secondary to consuming more whole foods rather than through supplements (Nutr Rev. 2001 May;59(5):129-39) and are therefore lost. Nevertheless, this study supports that a single dietary guideline—consuming a high fiber diet sourced primarily from whole food—will lead to weight loss, and potentially all the health benefits likely to come with it.