Fiber supplements are one way to add fiber to a weight-loss diet. Several trials have shown that supplementation with fiber from a variety of sources accelerated weight loss in people who were following a low-calorie diet.1, 2, 3, 4 Other researchers found, however, that fiber supplements had no effect on body weight, even though it resulted in a reduction in food intake.5 Supplementation with 3 to 4 grams per day of a bulking agent called glucomannan, with or without a low-calorie diet, has promoted weight loss in overweight adults,6, 7, 8 while 2 to 3 grams per day was effective in a group of obese adolescents in another controlled trial.9 However, guar gum, another type of fiber supplement, has not been effective in controlled studies for weight loss or weight maintenance.10, 11, 12