LeanFed

Gut & Hydration · Stages 1-4

Fiber Supplements

6 researched · scored on one published method · Updated October 2026

Psyllium, wheat dextrin, methylcellulose and PHGG, compared on fiber type and grams per serving. Food first; add fiber gradually, with fluid.

How we score

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.

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.

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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.

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.

How to chooseWho fiber supplements are for, what to check, and when not to buy.Show

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

  1. 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.
  2. 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.
  3. Fluid required per dose. Fiber supplements only work with enough liquid, and taking them dry is how they cause discomfort.
  4. 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.
  5. Added sugar, sugar alcohols and sweeteners in flavored versions.
  6. Whether it dissolves clear and tasteless enough to go into coffee, water or a shake you already drink.
  7. 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.

Go to the filters

The podium

The pickBenefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 TeaspoonsBenefiber Prebiotic Fiber Powder

The pick: Editorial rank #1 — LeanScore order unless a note below says otherwise

Wheat dextrin that dissolves clear into any drink.

Owner rating4.7 (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

Buy on Amazon
Runner-upNOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…NOW Psyllium Husk Capsules, 500 mg

Runner-up: Second in the editorial ranking

Capsules for people who cannot face another gritty glass.

Owner rating4.6 (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

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Also worth itMetamucil 4-in-1 Psyllium Husk GLP-1 Friendly Fiber Supplement,…Metamucil Psyllium Fiber Powder

Also worth it: Third in the editorial ranking — not the cheapest here

The most-studied psyllium powder, in the biggest tub.

Owner rating4.7 (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

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Fiber type, amount and container size

Only fields stated in the held label data are shown. Serving descriptions are kept verbatim because a scoop, teaspoon and capsule are not interchangeable.

ProductFiber typeFiber per servingServings per container
Benefiber Prebiotic Fiber PowderWheat dextrin3 g250 teaspoons
NOW Psyllium Husk Capsules, 500 mgPsyllium husk500 mg per capsule500 capsules
Metamucil Psyllium Fiber PowderPsyllium husk6 g57
Sunfiber PHGG Prebiotic Fiber PowderPartially hydrolysed guar gum (with probiotics)5 g30-day supply
Konsyl Daily Psyllium Fiber PowderPsyllium husk5 g per scoop90

At a glance

Side-by-side comparison

Prices & ratings checked Oct 10, 2026

№1 · Top pickBenefiber Prebiotic Fiber Powder

Owner rating4.7 · $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
Buy on Amazon

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.

Back to the filters ↑

Benefiber Prebiotic Fiber Supplement Powder, Unflavored, 250 Teaspoons

Benefiber

Benefiber Prebiotic Fiber Powder

Wheat dextrin that dissolves clear into any drink.

Owner rating 4.7(9,526)$22.98LeanScore 91

about $0.09 a serving

Available on subscription at the retailer.

Buy on AmazonSee Benefiber Prebiotic Fiber Powder details →
NOW Foods Supplements, Psyllium Husk Caps 500 mg, Non-GMO Project…

NOW Foods

NOW Psyllium Husk Capsules, 500 mg

Capsules for people who cannot face another gritty glass.

Owner rating 4.6(31,841)$23.09LeanScore 85

about $0.05 a serving

Buy on AmazonSee NOW Psyllium Husk Capsules, 500 mg details →
Metamucil 4-in-1 Psyllium Husk GLP-1 Friendly Fiber Supplement,…

Metamucil

Metamucil Psyllium Fiber Powder

The most-studied psyllium powder, in the biggest tub.

Owner rating 4.7(2,702)$29.99LeanScore 82

about $0.53 a serving

Buy on AmazonSee Metamucil Psyllium Fiber Powder details →
Tomorrow's Nutrition Sunfiber GI Prebiotic Fiber, 30-Day Supply

Tomorrow's Nutrition

Sunfiber PHGG Prebiotic Fiber Powder

Partially hydrolyzed guar gum, the low-bulk option.

Owner rating 4.6(642)$29.99LeanScore 81

— cost per serving not stated on the listing

Buy on AmazonSee Sunfiber PHGG Prebiotic Fiber Powder details →
Citrucel Powder Fiber Therapy for Occasional Constipation Relief,…

CITRUCEL

Citrucel Methylcellulose Fiber Powder

Non-fermenting fiber, often gentler on gas.

Owner rating 4.7(1,555)$39.30LeanScore 75

— cost per serving not stated on the listing

Buy on AmazonSee Citrucel Methylcellulose Fiber Powder details →
Konsyl Daily Psyllium Fiber Powder

Konsyl

Konsyl Daily Psyllium Fiber Powder

Unflavored psyllium with nothing else in the jar.

Owner rating 4.5(1,264)$25.99LeanScore 71

about $0.29 a serving

Buy on AmazonSee Konsyl Daily Psyllium Fiber Powder details →

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. If your intake changes, review possible fiber gaps with your care team rather than assuming a fixed drop in food or fiber intake. 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

Compare the listed fiber type, serving amount and mixing directions. A clear-dissolving powder is not evidence of better tolerance for you. Persistent fullness or constipation is a reason to ask your pharmacist or prescriber whether a supplement is appropriate; this shopping comparison cannot select one from your symptoms.

Ramp slowly, and always with fluid

Ask your pharmacist or prescriber how to introduce a supplement and follow its specific directions. Check its mixing and fluid instructions against any restrictions your care team has set. Tell them about other fiber products you already use.

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 appears in community discussions

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.

Threads we read ↓
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.

Questions we keep getting

Fiber Supplements: frequently asked

How much fiber should I be getting?

NIDDK puts the general adult target at 22 to 34 grams a day depending on age and sex, and frames fiber and fluid as a pair rather than a supplement on its own. Most products here deliver 2 to 6 grams per dose, which is how much of that gap one supplement can realistically close.

Why did fiber make me feel worse?

Often because it was the bulk-forming kind. Psyllium absorbs water and forms a gel, adding physical volume to a stomach that is already emptying slowly — the most common reason people report feeling worse rather than better. A non-bulk-forming fiber dissolves clear and adds far less volume.

Which type should I start with?

If fullness is already your limiting symptom, start non-bulk-forming: Benefiber is wheat dextrin at 3 grams a serving, Sunfiber is partially hydrolysed guar gum at 5. If bulk is not a problem, plain psyllium is the cheapest and best-studied option. Neither is better in general; the choice follows your symptoms.

How fast should I increase the dose?

Slowly, and always with liquid. Starting at the full label dose on day one is the classic route to gas and bloating, and fiber taken without enough fluid is the commonest way this goes wrong. Add one fiber product at a time, or you will not know which one you are reacting to.

When is this not a shopping problem?

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, and any product sold on a promise to purge or flush your system is making a claim it is not allowed to make.

Sources & research (5)Show
  1. 1gov2018NIDDK — Eating, Diet, and Nutrition for Constipation
  2. 2label2021FDA — Interactive Nutrition Facts Label: Dietary Fiber (October 2021)
  3. 3gov2021NIH Office of Dietary Supplements — Magnesium fact sheet for consumers
  4. 4gov2024FDA — Questions and Answers on Dietary Supplements
  5. 5govNIDDK — Treatment for Constipation

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

Fiber Supplements and GLP-1 Constipation: Start Here6 min readThe Food-First Constipation Kit for GLP-1 Days7 min read

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.