Calculate how much fiber you need per day based on your age, sex, and calorie intake — with weight loss recommendations.
Not sure about your calorie intake? Use our TDEE Calculator first.
Research consistently shows that increasing fiber intake supports weight loss. A landmark study published in the Annals of Internal Medicine found that simply aiming for 30 grams of fiber per day led to meaningful weight loss — comparable to more complex diets.
Fiber aids weight loss in several ways: it increases satiety (keeps you feeling full longer), slows digestion, stabilizes blood sugar, and feeds beneficial gut bacteria. For weight loss, aim for 25–35 grams per day, or roughly 14 grams per 1,000 calories consumed.
| Age Group | Men | Women |
|---|---|---|
| 19–30 | 38 g | 25 g |
| 31–50 | 38 g | 25 g |
| 51+ | 30 g | 21 g |
| Pregnant | — | 28 g |
| Breastfeeding | — | 29 g |
Most Americans only get about 15 grams per day — roughly half the recommended amount.
Fiber is a type of carbohydrate that your body can't fully digest. When tracking macros, some people subtract fiber from total carbs to get "net carbs." This is especially common on keto diets. However, fiber still provides about 2 calories per gram through fermentation in the gut.
To support your weight loss alongside fiber goals, calculate your calorie deficit and ensure adequate protein intake to preserve lean muscle mass.
The best sources of fiber for weight loss include: lentils (15g per cup), black beans (15g), split peas (16g), avocado (10g), chia seeds (10g per oz), broccoli (5g per cup), oats (4g per serving), raspberries (8g per cup), and pears (6g each). Focus on whole food sources rather than supplements for the best satiety effects.
Pair your fiber target with a full macro breakdown for optimal weight loss results.
Calculate Your Macros →No. Fiber itself doesn't cause weight gain. However, rapidly increasing fiber intake can cause bloating and gas, which might temporarily increase scale weight due to water retention. Increase fiber gradually — by about 5 grams per week — and drink plenty of water.
Soluble fiber dissolves in water and forms a gel, slowing digestion and helping lower cholesterol and blood sugar. Sources include oats, beans, and apples. Insoluble fiber doesn't dissolve — it adds bulk to stool and helps food pass through your gut. Sources include wheat bran, vegetables, and whole grains. Both types support weight loss.
Whole food sources are better than supplements for weight loss because they also contain water, vitamins, and minerals that increase satiety. However, psyllium husk supplements can be useful if you struggle to reach your fiber target through food alone.
Fiber promotes weight loss through four mechanisms: it increases feelings of fullness, slows gastric emptying (so you stay satisfied longer), reduces calorie absorption slightly, and feeds gut bacteria that produce short-chain fatty acids linked to reduced fat storage.