Fiber calculator for weight loss
Enter the calories you plan to eat and get the fiber to aim for each day, in grams, with a week-by-week plan to reach it.
Your daily calorie target while you lose weight. Between 1,000 and 4,000.
Not sure? The fiber quiz gives you an estimate in two minutes.
Your daily fiber target
25grams a day
How to get from 15g to 25g
Add about 5 grams a week and drink more water as you go. A fast jump is what causes gas and bloating.
- Week 120g a day
- Week 225g a day
Count your fiber each day with Grove
A target only helps if you know what you ate. Grove lets you search real foods and adds up your fiber for the day. On iPhone, iOS 18.0 or later.
How much fiber per day to lose weight?
There is no official fiber number made for weight loss. Aim for the higher of two published guidelines, and keep it there while your calories come down.
The first is the Institute of Medicine Adequate Intake: 25 grams a day for women and 38 for men up to age 50, then 21 and 30 after that. The second comes from the Dietary Guidelines for Americans: 14 grams of fiber for every 1,000 calories you eat.
One randomized trial that tested fiber for weight loss set its goal at 30 grams a day or more. The calculator shows that number next to yours so you can compare.
Does eating more fiber help you lose weight?
Two studies point that way. Here is what each one found, and what it did not.
A 30 gram goal against a full diet plan
In a 2015 trial in Annals of Internal Medicine, 240 adults with metabolic syndrome were split into two groups. One group got a single instruction: eat at least 30 grams of fiber a day. They were given no calorie goal. The other group followed the full American Heart Association diet.
After 12 months the fiber group had lost an average of 2.1 kilograms, about 4.6 pounds. The diet group had lost 2.7 kilograms, about 6 pounds. The authors wrote that the full diet may produce more weight loss, and that a fiber-only goal may be a reasonable choice for people who find a complicated diet hard to follow.
The limits matter. Everyone in the study had metabolic syndrome, so the result may not hold for other people, and the study did not follow anyone past 12 months.
Fiber as a predictor on a calorie-cut diet
A 2019 analysis in The Journal of Nutrition looked at 345 adults with overweight or obesity from the POUNDS Lost study. All of them were put on diets 750 calories a day below what they needed, for six months. Of everything the researchers measured, fiber intake was the strongest predictor of how much weight a person lost. People who ate more fiber also stuck to their assigned diet more closely.
This was an analysis of an existing trial, and everyone in it was already cutting calories. It does not show that fiber leads to weight loss if you keep eating the same amount.
Should you eat less fiber when you cut calories?
No. This is the mistake the calculator is built to catch. The 14 grams per 1,000 calories rule gives a smaller number as calories drop. At 1,400 calories it gives 20 grams.
The Adequate Intake for your age and sex does not shrink with a diet. A woman under 51 still has a 25 gram guideline at 1,400 calories. So the calculator takes the higher of the two numbers and uses that as your target.
How to use this calculator
- Enter the calories you plan to eat each day.
- Enter your age and pick your sex.
- Enter the fiber you eat now. If you do not know, take the fiber quiz first.
- Read your daily target and the week-by-week plan under it.
This calculator is for adults. It does not set your calories, and nothing you enter is saved. For a fiber goal that is not tied to weight loss, use the fiber calculator.
Questions
How much fiber should I eat per day to lose weight?
There is no official fiber number made for weight loss. The standing guidelines are 25 grams a day for women and 38 for men up to age 50, then 21 and 30 after that, or 14 grams for every 1,000 calories you eat. One randomized trial that tested fiber for weight loss set a goal of at least 30 grams a day.
Does eating more fiber help you lose weight?
Two studies point that way. In a 2015 trial of 240 adults with metabolic syndrome, people told only to eat at least 30 grams of fiber a day lost an average of 2.1 kilograms in 12 months, and people on the full American Heart Association diet lost 2.7. In a 2019 analysis of 345 adults on calorie-restricted diets, fiber intake was the strongest predictor of weight loss at six months. Neither study shows that fiber causes weight loss without eating fewer calories.
Should I eat less fiber when I cut calories?
No. The 14 grams per 1,000 calories rule gives a smaller number as calories drop, but the Adequate Intake for your age and sex does not shrink with a diet. This calculator keeps the higher of the two, so a 1,400 calorie plan still gets a 25 gram target for a woman under 51.
Is 30 grams of fiber a day good for weight loss?
Thirty grams a day is the goal used in the 2015 Annals of Internal Medicine trial, where it led to an average loss of 2.1 kilograms over a year with no calorie goal at all. It is above the guideline for women and below the guideline for men under 51, so use it as a reference point next to your own target.
How fast should I increase my fiber?
Add about 5 grams a week and drink more water as you go. A sudden jump is what causes gas and bloating. Going from 15 grams to 25 takes about two weeks at that pace.
Does this calculator tell me how many calories to eat?
No. You enter the calorie target you already have. The calculator only works out the fiber that fits it. Talk to a doctor or a registered dietitian before starting a weight loss diet, especially if you have a health condition or a digestive disorder.
Sources: Ma et al., Annals of Internal Medicine, 2015, Miketinas et al., The Journal of Nutrition, 2019, Institute of Medicine Dietary Reference Intakes, and the Dietary Guidelines for Americans. Last reviewed .
This page is general information, not medical advice. Talk to a doctor or a registered dietitian before you start a weight loss diet, especially if you have a health condition or a digestive disorder.
Track your fiber intake with Grove
Search real foods, hit your daily goal, and build a gut health habit. On iPhone, iOS 18.0 or later.