Does taking a fiber supplement enhance weight loss? Original paper

In this randomized controlled trial in participants with overweight or obesity who consumed a hypocaloric diet, taking a fiber supplement daily resulted in greater weight loss than a placebo.

Whether taking a fiber supplement daily enhances weight loss (the primary outcome) in participants with overweight or obesity.

The secondary outcomes were BMI, visceral fat rating, fat mass, appetite, gastrointestinal symptoms, fasting glucose, blood pressure, blood lipids, and high-sensitivity C-reactive protein.

112 participants (average age of 46; 72% women, 28% men) with overweight or obesity.

In this approximately 6-month randomized controlled trial, the participants took either a fiber supplement or a placebo daily. The fiber supplement contained glucomannan, inulin, and psyllium. The participants were instructed to consume 3 powder bags of the supplement daily (30 minutes before each meal), and each bag contained 1 gram of glucomannan, 1 gram of inulin, and 3 grams of psyllium.

All of the participants received nutrition counseling to promote adherence to a hypocaloric diet (daily energy deficit of 500 kcal).

Appetite was measured by having the participants fill out a visual analog scale following a standardized breakfast at the end of the study. Thirty minutes before the standardized breakfast, the participants took their assigned supplement. Gastrointestinal symptoms were reported weekly using a questionnaire.

Subgroup analyses were performed to determine whether SNPs in obesity-related genes (FTO, LEP, LEPR, and MC4R) influenced the results.

Compared to baseline, weight, BMI, fat mass, visceral fat rating, and systolic and diastolic blood pressure decreased in both groups, but there were greater decreases in weight (−6.5 kg vs. −2.2 kg), BMI (−2.2 vs. −0.8), fat mass (−19.4% vs. −6.4%), and visceral fat rating in the fiber group. Additionally, the odds of losing ≥5% and ≥10% of baseline weight were 400% and 280% higher, respectively, in the fiber group.

Subgroup analysis indicated that weight loss was greater in participants who had 2 copies of the minor allele for at least one obesity-related gene, compared to the participants who had other genetic configurations.

After the standardized breakfast, hunger was lower and fullness/satiety was higher in the fiber group than the placebo group. Lastly, 75% of participants in the fiber group reported at least one event of gastrointestinal symptoms (mild flatulence was most frequently reported).

The company that manufactures the fiber supplement provided the supplements for the study, but none of the researchers were affiliated with the company.