4.7 · $22.98 · LeanScore 91
- Cost per serving
- $0.09 / serving
- Fiber type
- Wheat dextrin
- Fiber/serving
- 3 g
- Servings
- 250 teaspoons
- Form
- Powder
- Flavor
- Unflavored
- Added sugar
- Sugar-free
Gut & Hydration · Stages 1-4
Fiber Supplements
6 researched · scored on one published method
Psyllium, wheat dextrin, methylcellulose and PHGG, compared on fiber type and grams per serving. Food first; add fiber gradually, with fluid.
Emergency — go nowSome symptoms are not a shopping problem
Severe or persistent abdominal pain, vomiting you can't stay ahead of, signs of dehydration, allergic symptoms, or a sudden change in vision are reasons to contact your prescriber or seek urgent care — not reasons to buy something. Nothing on this page treats, prevents or cures a side effect; these products may help with convenience, comfort, intake or tracking. Dose and timing are your prescriber's call, and we never cover them.
Quick answer
For someone whose stomach is already emptying slowly, the type that tends to win is a non-bulk-forming, clear-dissolving fiber you can stir into a drink you already finish, started well below the label dose and increased over a couple of weeks. Plain psyllium remains the cheapest and best-studied option and is the right pick for people who tolerate bulk, but it is the wrong first try if fullness is already the limiting symptom.
- Top pickEditorial rank #1 — LeanScore order unless a note below says otherwiseBenefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 TeaspoonsStirring into coffee or soup without changing how it tastes or looks.$22.98See the pick →
- Best valueHighest LeanScore per dollar of the priced picksNOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…People who cannot face another gritty glass but still want psyllium.$23.09See the pick →
- Cheapest hereLowest listed pack price of the picks hereKonsyl Daily Psyllium Fiber PowderOne ingredient and no flavour, so it can go into food instead of a glass.$25.99See the pick →
Narrow this shelf
All 6 picks shown
Narrows “Every pick, reviewed” further down this page. The podium and the comparison table always show the full ranking.
Dietary statements
These match only what a listing states. A pick whose listing says nothing either way is hidden while a chip is on — that is a gap in the label, not a verdict on the product.
Before the numbers
Has a clinician set limits on your protein, fluid, sodium or potassium?
We never ask for a condition and never store one — this is one of three words kept in this browser, and you can clear it on your device page. Nothing below is hidden either way.
The fiber figures on this shelf are general reference figures from published sources and from product labels. They are not a target, they are not personalised, and nothing here adjusts them for age, kidney function, heart or blood-pressure conditions, pregnancy or anything else. A clinician is the only person who can set a number for you.
Before the picks
How to choose fiber supplements
You are eating far less food than you used to, so you are almost certainly eating far less fiber than you used to, and things have slowed down. A fiber supplement is a way to close that gap when the food route is not realistic on a small appetite.
What to check on the label
- Bulk-forming versus non-bulk-forming. Psyllium adds bulk and water; partially hydrolyzed guar gum and wheat dextrin dissolve clear and add far less volume. On a small appetite that distinction matters more than the gram count.
- Grams of fiber per dose and how many doses the label expects, measured against the 22 to 34 grams a day adults are generally advised to get.
- Fluid required per dose. Fiber supplements only work with enough liquid, and taking them dry is how they cause discomfort.
- Format: powder, capsule or gummy. Gummies typically carry only two to five grams per serving, which is a much smaller contribution than the powder equivalent.
- Added sugar, sugar alcohols and sweeteners in flavored versions.
- Whether it dissolves clear and tasteless enough to go into coffee, water or a shake you already drink.
- Cost per gram of fiber, which varies by roughly an order of magnitude between plain psyllium husk and branded gummies.
You may not need to buy anything
Skip a supplement if you can still get fiber from food, which is the approach public health guidance leads with. Skip bulk-forming psyllium if you already feel uncomfortably full — adding bulk to a stomach that is emptying slowly is the single most common reason people say fiber made things worse. And skip all of this and talk to your clinician if you have severe or persistent abdominal pain, vomiting, blood in the stool, or you have not passed stool for days.
Food first, always. Nothing on this page treats, prevents or cures a side effect, and anything that touches your medication — dose, timing, whether to take something alongside it — is your prescriber's call. The Path is free and has no products in it.
Narrow the shelf first
Filter the full shelf by price, dietary statements and what the label actually says, before you read a single pick.
LeanFed may earn a commission from links on this page; it never changes a ranking. Full disclosure.
The podium
The pick
Benefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 Teaspoons
Benefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 TeaspoonsThe pick: Editorial rank #1 — LeanScore order unless a note below says otherwise
Wheat dextrin that dissolves clear into any drink.
4.7 (9,526) · $22.98 · LeanScore 91
about $0.09 a serving
Why this one leads: It carries the highest LeanScore on this shelf (91 against 85 for the next-highest-scoring pick here), and it is the least expensive of the picks here. Prices move — check the listing before you decide.
A substantial group argues the problem is slowed transit rather than missing bulk, and looks for a fibre that dissolves clear instead of one that adds volume.
Paraphrased from r/Mounjarosource
Runner-up
NOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…
NOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…Runner-up: Second in the editorial ranking
Capsules for people who cannot face another gritty glass.
4.6 (31,841) · $23.09 · LeanScore 85
about $0.05 a serving
Plain psyllium is the most-named ingredient, and capsules come up as the version people stay with when another gritty glass is unappealing.
Paraphrased from r/Mounjarosource
Also worth it
Metamucil 4-in-1 Psyllium Husk GLP-1 Friendly Fiber Supplement,…
Metamucil 4-in-1 Psyllium Husk GLP-1 Friendly Fiber Supplement,…Also worth it: Third in the editorial ranking — not the cheapest here
The most-studied psyllium powder, in the biggest tub.
4.7 (2,702) · $29.99 · LeanScore 82
about $0.53 a serving
Every fibre recommendation in these threads arrives attached to a hydration instruction: start small, and drink far more water than expected.
Paraphrased from r/Zepboundsource
At a glance
Side-by-side comparison
Prices & ratings checked Aug 22, 2026
4.6 · $23.09 · LeanScore 85
- Cost per serving
- $0.05 / serving
- Fiber type
- Psyllium husk
- Fiber/serving
- 500 mg per capsule
- Servings
- 500 capsules
- Form
- Capsules
4.7 · $29.99 · LeanScore 82
- Cost per serving
- $0.53 / serving
- Fiber type
- Psyllium husk
- Fiber/serving
- 6 g
- Servings
- 57
- Form
- Powder
- Flavor
- Orange
- Added sugar
- Sugar-free
4.6 · $29.99 · LeanScore 82
- Cost per serving
- — not stated on the listing
- Fiber type
- Partially hydrolysed guar gum (with probiotics)
- Fiber/serving
- 5 g
- Servings
- 30-day supply
- Form
- Powder
4.7 · $39.30 · LeanScore 75
- Cost per serving
- — not stated on the listing
- Fiber type
- Methylcellulose
- Fiber/serving
- 2 g per rounded tablespoon
- Form
- Powder
- Flavor
- Orange
- Added sugar
- Sugar-free
4.5 · $25.99 · LeanScore 71
- Cost per serving
- $0.29 / serving
- Fiber type
- Psyllium husk
- Fiber/serving
- 5 g per scoop
- Servings
- 90
- Form
- Powder
- Flavor
- Unflavored
- Added sugar
- Zero sugar
LeanScore is 72% owner satisfaction and 28% value, computed the same way in every category and published in full on our methodology page. It is not a lab result and not a nutrition rating. Rows are in editorial rank order, which is LeanScore order unless a note under the top row explains why we ranked it differently — the two are separate things and we never silently reorder one to match the other. Worked out from the listing's own numbers: the price we last checked, divided by the servings the label states, then scaled to 20 g of protein where protein per serving is stated. Where a listing doesn't state servings or protein, we show a dash rather than an estimate. The italic lines under a pick are paraphrased consensus from public forum threads — never quotes, never usernames — and each one links the thread it came from. LeanFed may earn a commission from links in this table; it never changes a ranking.
The full shelf
Every pick, reviewed
Filter by what the listings actually state. A pick that says nothing about a dietary point is hidden while that filter is on — that is a gap in the label, not a verdict on the product.
Benefiber
Benefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 Teaspoons
Wheat dextrin that dissolves clear into any drink.
4.7(9,526)$22.98LeanScore 91
about $0.09 a serving
NOW Foods
NOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…
Capsules for people who cannot face another gritty glass.
4.6(31,841)$23.09LeanScore 85
about $0.05 a serving
Metamucil
Metamucil 4-in-1 Psyllium Husk GLP-1 Friendly Fiber Supplement,…
The most-studied psyllium powder, in the biggest tub.
4.7(2,702)$29.99LeanScore 82
about $0.53 a serving
Tomorrow's Nutrition
Tomorrow's Nutrition Sunfiber GI Prebiotic Fiber, 30-Day Supply
Partially hydrolyzed guar gum, the low-bulk option.
4.6(642)$29.99LeanScore 82
— cost per serving not stated on the listing
CITRUCEL
Citrucel Powder Fiber Therapy for Occasional Constipation Relief,…
Non-fermenting fiber, often gentler on gas.
4.7(1,555)$39.30LeanScore 75
— cost per serving not stated on the listing
Konsyl
Konsyl Daily Psyllium Fiber Powder
Unflavored psyllium with nothing else in the jar.
4.5(1,264)$25.99LeanScore 71
about $0.29 a serving
Price we last checked ÷ servings stated on the label. A dash means the listing doesn't state it.
Applies toUnited States listings. Every price, rating and link on this page comes from the US store of the affiliate retailer we use, and nutrition labelling rules differ between countries.
How to pick one, in fullThe long-form buying guide for this shelf.Show
Before anything on this page: severe or persistent abdominal pain, repeated vomiting, blood in the stool, or several days with no bowel movement are reasons to contact your prescriber, not reasons to buy a supplement. Nothing in this category treats a medical problem.
Food first, honestly
The standard advice is to get fiber from food and to drink enough liquid to help it work. On a GLP-1 that advice runs into a real wall — when total food volume drops by half, fiber drops with it. So a supplement here is a gap-filler for a specific, understandable reason, not a shortcut past the food.
Know the target you are filling toward: adults are generally advised to get 22 to 34 grams of fiber a day, depending on age and sex. Most fiber supplements deliver 2 to 6 grams per dose, which frames how much of the gap one product can realistically close.
Bulk-forming or not — this is the fork in the road
- Bulk-forming (psyllium): absorbs water and forms a gel, adding physical volume. Cheap, well studied, and effective for many people. But it adds bulk to a stomach that is already emptying slowly, which is exactly why some people report feeling worse.
- Non-bulk-forming (partially hydrolyzed guar gum, wheat dextrin): dissolves clear, adds far less volume, and is the more forgiving starting point when fullness is already your limiting symptom.
Neither is "better". They are different tools, and the choice follows your symptoms.
Ramp slowly, and always with fluid
Start at roughly a quarter to a half of the label dose, hold there for several days, and only then increase. Take it with a full glass of liquid every time — fiber without fluid is the most common way this goes wrong. Add one fiber product at a time; if you are simultaneously eating a 13 g fiber bar and a fortified cereal, you have no idea which one you are reacting to.
Red flag: any product sold on a promise to purge or flush your system, or as a fix for a side effect. Fiber is a nutrient, not a treatment, and a supplement that promises to solve a medication side effect is making a claim it is not allowed to make.
Format, honestly
Powder gives you dose control and the best cost per gram. Capsules are convenient but you may need several to equal one powder dose — read the panel. Gummies usually carry only a few grams per serving and are the most expensive fiber on the shelf; they are a fine habit-builder and a poor gap-filler.
Also check the label for magnesium-based products sitting next to the fiber on the shelf. They are a different category with different considerations, and high intakes of magnesium from supplements can cause diarrhea, nausea and cramping.
What the communities keep sayingParaphrased patterns from public forum threads, with the threads linked.Show
communityAugust 2026Paraphrased from public threads, read on that date. Not measured data — these forums give us no vote counts.
Constipation is described as near-universal and worse than expected
Threads titled around this exact problem recur constantly in r/Zepbound, r/Mounjaro and r/WegovyWeightLoss, often from people who had never experienced it before starting. New users are frequently told to plan for it in advance rather than react to it.
A substantial group reports that bulk fiber made it worse
In r/Mounjaro in particular, several people argue that the problem is slowed transit rather than a lack of bulk, and that adding a bulk-forming fiber therefore backfired for them. The alternative they name is a non-bulking fiber or a stool softener rather than more psyllium.
Psyllium is the most-recommended single ingredient
Plain psyllium husk, in powder or capsule form, is the most frequently named product across all five subs, usually with the advice to take it with much more water than expected and to start small. People often note it is the main ingredient in the branded powders at a fraction of the price.
Water is treated as the other half of the intervention
Nearly every fiber recommendation in these subs arrives attached to a hydration instruction. Posters describe fiber without adequate fluid as making things noticeably worse.
Sugar-free fiber gummies are a recurring source of gas complaints
Several people in r/Mounjaro report switching from sugar-free fiber gummies to plain capsules because the gummies produced gas or bloating. The sweeteners rather than the fiber are what they blame.
Paraphrased consensus from 64 threads · r/Mounjaro, r/Zepbound · August 2026. We summarise what comes up repeatedly and link the threads — we never quote or identify anyone, and these forums don't give us vote counts, so treat this as the shape of the conversation rather than a measured majority.
Mistakes that keep coming up, and how we choseThe recurring buying errors, and the method behind this shelf.Show
- Starting at the full label dose. Fiber should go up gradually; a full dose on day one is the classic route to gas and bloating.
- Taking fiber without enough fluid. Liquid is what makes fiber work, and skipping it can make constipation feel worse rather than better.
- Assuming all fiber supplements behave the same. Bulk-forming and non-bulk-forming fibers do genuinely different things, and people who react badly to one often do fine on the other.
- Reaching for a supplement before checking hydration and food. Both are upstream of this and both are commonly the actual problem.
- Buying gummies expecting powder-sized results. Read the grams per serving before comparing prices.
How we chose: We compared label panels for fiber type, grams per dose, fluid instructions and added sweeteners, and grouped products by whether the fiber is bulk-forming. Owner reviews were read for recurring themes about bloating, taste and mixability. We do not test products, we do not give medical advice, and nothing here is a treatment recommendation — constipation that is severe, painful or persistent is a conversation with your prescriber.
Sources & research (13)Show
- 1gov2018NIDDK — Eating, Diet, and Nutrition for Constipation
- 2label2021FDA — Interactive Nutrition Facts Label: Dietary Fiber (October 2021)
- 3gov2021NIH Office of Dietary Supplements — Magnesium fact sheet for consumers
- 4gov2024FDA — Questions and Answers on Dietary Supplements
- 5orgElahi Vahed I et al. — The effect of berberine on obesity indices: a systematic review and meta-analysis (International Journal of Obesity, 2026) — Source for the pooled mean weight reduction of 0.88 kg (95% CI −1.36 to −0.39) across 23 randomized trials, and for the authors' call for better reporting of purity, potency and gram amounts and for fixing the lack of blinding. Record confirmed via the EuropePMC REST API (PMID 41310257).
- 6govNCCIH — Berberine and Weight Loss: What You Need To Know — Source for effects appearing mainly above one gram a day for more than eight weeks, the high risk of bias in included studies, the concentration of research in Asian countries and in participants with diabetes or fatty liver disease, the cyclosporine interaction, the infant and pregnancy cautions, and the reported gastrointestinal side effects.
- 7orgTian H et al. — Chromium picolinate supplementation for overweight or obese adults (Cochrane Database of Systematic Reviews, 2013) — Source for the nine trials and 622 participants, the mean difference of −1.1 kg (95% CI −1.7 to −0.4) after 12 to 16 weeks described as of debatable clinical relevance on low-quality GRADE evidence, and the authors' conclusion that they found no current, reliable evidence to inform firm decisions. Record confirmed via the EuropePMC REST API (PMID 24293292).
- 8orgZalewski BM et al. — The effect of glucomannan on body weight in overweight or obese children and adults: a systematic review of randomized controlled trials (Nutrition, 2015) — Source for the six included trials, the short-term body-weight reductions reported in three of the adult trials, and the finding that none of the trials reported a favourable effect on BMI. Record confirmed via the EuropePMC REST API (PMID 25701331).
- 9govNCCIH — Green Tea: Usefulness and Safety — Source for the modest effect of catechins and caffeine on body weight, and for liver injury reported in some people using green tea extracts in tablet or capsule form.
- 10govNCCIH — Weight Control — Source for the statements that analyses of dietary supplements sometimes find differences between labelled and actual ingredients, and that FDA has found weight-loss products tainted with prescription drug ingredients. Page last updated September 2017, which we say in the article.
- 11orgAronne LJ et al. — Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5), New England Journal of Medicine 2025;393:26-36 — Used only for the scale comparison: 751 adults with obesity and without type 2 diabetes, mean weight change at week 72 of −20.2% with tirzepatide and −13.7% with semaglutide. Record confirmed via the EuropePMC REST API (PMID 40353578).
- 12govFDA — FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss — Source for the standing warning about counterfeit and fraudulent versions of these medications sold into the same demand these supplements ride.
- 13govNIDDK — Treatment for Constipation — Source for regular physical activity, the same-time-each-day routine and the 15 to 45 minutes after breakfast suggestion, and for the reasons to see a health care professional including long-term laxative reliance.
The tag says what kind of source a link is; the year is the revision or publication year the page itself states, and is left off where the page states none. Every URL here was opened and read — a source list proves a page loads, not that it says what we claim, so we check the second part by hand.
Read alongside
Guides for buying Fiber Supplements
We do not test products — we compare labels, specifications and owner reviews. Prices and ratings shown are the most recent values we pulled from affiliate retailers and refresh on a recurring cycle; confirm the current price and read the product's own label before buying. See how we score.