Does fiber help you lose weight?

Short answer

Yes, but fiber in your meals did more than fiber powders. Supplements added about 1 kg of extra loss, while fiber from food helped people stick to their diet and cut absorbed calories by 116 kcal a day.

Does fiber help you lose weight?
'More fiber → fuller → less weight' — does this formula hold?
A common belief: fiber fills you up, so you eat less and lose weight. We checked how much fiber supplements and fiber from food actually changed body weight.
Fiber supplements added a little extra loss
12+ weeks of use meant 1.25 kg more lost
An analysis that pooled 27 trials with 1,428 people taking soluble fiber supplements for 12 weeks or more found they lost 1.25 kg more. In 15 studies with 1,347 people who cut calories and added thick, gel-forming fiber, the extra loss was 0.81 kg.
But single products made no difference
Konjac fiber and psyllium: 0.2-0.3 kg
The supplement effect was small, around 1 kg. An analysis of 8 trials on konjac fiber (glucomannan) found 0.22 kg, and an analysis of 22 trials on psyllium found 0.28 kg, with no difference from people not taking them.
Fiber in food helped people stick to the diet
The strongest predictor in 345 people
345 people on a diet cutting 750 kcal a day for 6 months lost 7.27 kg on average. Even after accounting for their protein, fat and carb mix and calories, those who ate more fiber lost more, and fiber was the strongest predictor of weight loss. People who ate more fiber also stuck to their assigned diet better.
A fiber-only goal still worked
Just 0.6 kg apart from a complex diet
240 people were split for 12 months: one group had a single goal of 30 g or more of fiber a day, the other followed the multi-rule American Heart Association diet. They lost 2.1 kg and 2.7 kg, a 0.6 kg gap that was not a meaningful difference. Fiber intake at the start was 19.1 g a day on average.
Fiber also cut the calories you absorb
Same calories in, 116 kcal a day went out
17 people ate the same calories on a diet high in fiber and resistant starch and on a typical Western diet, in turn. On the high-fiber diet, 116 kcal more a day left in the stool, and the share absorbed fell from 95.4% to 89.5%. Hunger and food intake showed no difference.
Bottom line: fiber helps weight loss
30 g a day from meals beats powders
Fiber supplements added about 1 kg of extra loss, and single products made no difference. Fiber from food helped people stick to their diet and cut absorbed calories by 116 kcal a day, which adds up to about 3,480 kcal a month. Raising fiber from around 19 g to 30 g or more a day is enough.