Why are casein based powders excluded?

Casein forms a thicker curd in the stomach and digests slowly. Since GLP-1 medications already slow gastric emptying, this list only includes powders whose lead protein is whey, filtered milk or a plant protein.

How much protein do I need on a GLP-1 medication?

Research supports a minimum of 0.54g per lb (1.2g/kg) of body weight per day during GLP-1 treatment to help preserve lean mass. Our GLP-1 protein calculator does the math for your weight.

How often does this list change?

It recomputes automatically from verified label data, so new powders appear as soon as they are published and verified, and any powder that gets reformulated is checked again against the same criteria.

Best Protein Powder for GLP-1 Users

On a GLP-1 medication like Ozempic, Wegovy, Mounjaro or Zepbound, a protein shake made from powder is often the most practical way to protect protein intake when appetite is low. Every powder below meets a strict, transparent standard: at least 20g of protein, 160 calories or less, 3g of sugar or less and 3g of fat or less per serving, with casein led formulas excluded because casein digests slowly and GLP-1 medications already slow the stomach. Qualifying powders are ordered by protein per calorie. Prefer a ready made drink? See our guide to protein shakes on GLP-1. Prefer a bar? See the GLP-1 protein bars list, and if you don’t know your protein target yet, the GLP-1 protein calculator gives you a number in seconds. This is nutrition information, not medical advice; always follow your clinician’s guidance.

Rankings recompute automatically as new verified products are added. Tap a column to sort; product lines with multiple flavours show their best scoring flavour.

#	Product
1	Isopure Zero Carb6 flavours	25g	100	25g	0g	0g	29g
2	Optimum Nutrition Gold Standard 100% Isolate2 flavours	25g	100	25g	≤1g	0g	30g
3	Nutricost Whey Protein Isolate13 flavoursvaries by flavour	30g	130	23.1g	≤1g	0g	35g
4	Ascent Native Fuel Whey12 flavoursvaries by flavour	25g	110	22.7g	≤1g	0g	30g
5	Dymatize ISO10014 flavours	25g	110	22.7g	≤1g	0g	30g
6	Isopure Low Carb3 flavours	25g	110	22.7g	0g	0g	32g
7	Naked Nutrition Naked PeaUnflavored	27g	120	22.5g	2g	0g	30g
8	PEScience Select Protein13 flavoursvaries by flavour	24g	110	21.8g	0.5g	0.5g	31g
9	Quest Protein Powder6 flavoursvaries by flavour	24g	110	21.8g	≤1g	0g	31g
10	Body Fortress Super Advanced Isolate2 flavours	30g	140	21.4g	0.5g	0g	38g

Powders marked “contains maltitol” include a sugar alcohol some people prefer to avoid. What are sugar alcohols?

Note: This page is nutrition information only, not medical advice. Nothing here is a claim that any product treats, prevents or reduces side effects of any condition or medication. Always follow your clinician’s guidance on nutrition while taking GLP-1 medications.

Why powders work well on a GLP-1

The practical problem on these medications is volume: a full meal can feel impossible, but 20 to 30g of protein mixed into water or milk usually is not. Whey isolates dominate this list because nearly every calorie is protein, they are low in the lactose that can upset a slowed stomach, and serving sizes stay small.

One standard, every GLP-1 medication

Ozempic and Wegovy are both semaglutide; Mounjaro and Zepbound are tirzepatide. All four suppress appetite and slow digestion, and the criteria on this page describe the powder rather than the medication, so the qualifying list is the same whichever one you take.

The criteria, explained

Every cap has a reason, drawn from published clinical guidance where it exists (linked in the research section below). Nothing here is arbitrary, and nothing here is medical advice.

Protein floorat least 20g per serving: Clinical guidance for people on weight loss medications recommends 60 to 75g of protein per day, up to 0.68g per lb (1.5g per kg) of body weight, and describes formulated products carrying 15 to 25g of protein per serving as a useful supplement when whole food intake is not enough (Almandoz 2024). With a suppressed appetite each item has to carry real protein, so our floor sits at the top of that per serving range.
Calorie cap160 kcal or less: Appetite suppression usually means a much smaller daily intake, so every item needs to earn its place. The cap stops a single bar from taking up a disproportionate share of a reduced day.
Sugar cap3g or less: A joint clinical advisory recommends avoiding refined sugars during GLP-1 therapy, and when portions are small, sugar displaces protein without adding satiety. A label that does not state sugar fails this check; unknown is never treated as zero.
Fat cap3g or less: Clinical guidance specifically advises limiting fried and high fat foods on these medications to reduce gastrointestinal side effects such as nausea (Almandoz 2024).
Protein densityat least 6g of protein per 100 calories: Guarantees protein leads the product rather than fillers, whatever the serving size. This is the primary ranking metric on this page: it answers how much protein you get for the calories you spend.
Fiber (ranking factor, not a cap)more is better: No minimum is required, but among qualifying products more fiber ranks higher: clinical guidance flags fiber as a priority nutrient when eating less, and it contributes to satiety.
Sugar alcohols (ranking factor, not a cap)fewer is better: Among products with equal protein scores, those without maltitol, sorbitol, xylitol, isomalt, mannitol or lactitol rank first, and products containing them are marked. This is a precaution, not a warning: a single bar is well below the doses where studies find symptoms in healthy adults, and the mark matters most for people with sensitive digestion. Erythritol is not penalised. What are sugar alcohols?
Serving size (ranking factor, not a cap)smaller is better: A smaller bar is simply easier to finish when appetite is suppressed, so among otherwise equal products the smaller one ranks higher. The size column in the table shows grams per serving.

Others worth considering

These lines hit the key standard, a strong protein to calorie ratio, but each misses the strict criteria on one debatable point, noted below. Depending on your priorities they can still be a solid pick; the note is something to weigh up, not a hard line.

Body Fortress Super Advanced Whey5 flavours checked; closest: Chocolate Peanut Butter
- 180 kcal, just over the 160 kcal cap
Vega Performance Protein + Recovery5 flavours checked; closest: Berry
- 170 kcal, just over the 160 kcal cap
Optimum Nutrition Gold Standard 100% Casein4 flavours checked; closest: Chocolate Peanut Butter
- first protein is micellar casein: casein digests more slowly than the whey based options we prioritise (see research notes)
Six Star 100% Whey Protein Plus3 flavours checked; closest: Strawberry Smoothie
- 170 kcal, just over the 160 kcal cap

Why some popular powders miss the cut

Product lines where no flavour meets the criteria, and what the label analysis surfaced for each line’s closest flavour. This updates automatically as products are verified and reformulations are checked again.

Vital Proteins Collagen Peptides6 flavours checked; closest: Chocolate
- 18g protein (needs 20g+)
Muscle Milk Genuine Protein Powder5 flavours checked; closest: Chocolate
- 270 kcal (cap 160)
- 9g fat (cap 3g)
Muscle Milk Pro Series Protein Powder3 flavours checked; closest: Intense Vanilla
- 310 kcal (cap 160)
- 4g fat (cap 3g)

What are sugar alcohols, and why is maltitol marked?

Sugar alcohols (also called polyols) are sweeteners such as maltitol, sorbitol, xylitol and erythritol that manufacturers use to keep the sugar line on the label low while the powder still tastes sweet. They are not alcohol in the drink sense. Because most of them are only partially absorbed, the unabsorbed portion ferments in the gut, which is why larger amounts can cause bloating, gas and laxative effects. European law requires a laxative effect warning on any food that is more than 10% polyols.

Maltitol is the one we mark most often: it is common in sugar free protein products and it is the sugar alcohol with the clearest evidence of digestive discomfort at higher intakes. Honest context on the doses: in studies of healthy adults, 30g of maltitol caused no significant symptoms versus sugar, and a single serving contains well below that. The mark matters most for people with sensitive digestion (these sugar alcohols are excluded from low FODMAP diets used for irritable bowel syndrome, and sensitive people report symptoms at lower doses) and for anyone eating several sugar free products in a day, since the effects scale with total intake. Erythritol is the exception in the family; it is mostly absorbed and excreted unchanged, so we never penalise it. GLP-1 medications commonly cause digestive side effects of their own, which is why some users prefer to know exactly which sweeteners are in a powder before choosing one. The research for all of this is linked at the bottom of the page.

How this ranking works

Every nutrition value is transcribed from the manufacturer’s published nutrition label and verified by hand, with no third party food databases.
Product lines are ranked, not individual flavours, so one product’s 20 flavours can’t fill the list. Each entry shows its best scoring flavour.
A maximum of two lines per brand keeps the list diverse.
Labels that don’t state sugar or fiber are treated as unknown (never as zero) and are excluded from sugar and fiber rankings.
Want to hit a daily protein target? The Protein Pal app lets you scan any label and track your protein day by day.

Frequently asked questions

Why are casein based powders excluded?: Casein forms a thicker curd in the stomach and digests slowly. Since GLP-1 medications already slow gastric emptying, this list only includes powders whose lead protein is whey, filtered milk or a plant protein.
How much protein do I need on a GLP-1 medication?: Research supports a minimum of 0.54g per lb (1.2g/kg) of body weight per day during GLP-1 treatment to help preserve lean mass. Our GLP-1 protein calculator does the math for your weight.
How often does this list change?: It recomputes automatically from verified label data, so new powders appear as soon as they are published and verified, and any powder that gets reformulated is checked again against the same criteria.

The research behind these criteria

Three honest caveats. First, no study has tested sugar alcohols specifically in people taking GLP-1 medication; we mark them because GLP-1 medications and larger doses of polyols are each independently associated with gastrointestinal symptoms, and some users prefer to avoid the combination. Second, a single bar contains well below the 30 to 40g maltitol doses where studies begin to find symptoms in healthy adults; the mark matters most for sensitive people (maltitol is excluded from low FODMAP diets used for irritable bowel syndrome) and for anyone eating several sugar free products in a day. Third, the casein research shows slower digestion and a smaller immediate muscle protein synthesis response than whey, not harm; bars that lead with casein are still quality protein, which is why they appear under "others worth considering" rather than being hidden.

Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1) · Wilding et al., New England Journal of Medicine, 2021
Gastrointestinal side effects (nausea, diarrhea, vomiting, constipation) were the most common with semaglutide, reported by 74% of participants versus 48% on placebo. This is why we surface this label information at all.
Gastrointestinal tolerability of once-weekly semaglutide 2.4 mg · Wharton et al., Diabetes, Obesity and Metabolism, 2022
Detailed analysis of gastrointestinal side effects across the STEP trials: mostly mild to moderate and transient, but common.
Nutritional considerations with antiobesity medications · Almandoz et al., Obesity, 2024
Clinical guidance for people on weight loss medications: at least 60 to 75g of protein per day (up to 0.68g per lb / 1.5g per kg of body weight), formulated products carrying 15 to 25g of protein per serving as a useful supplement when whole food intake is not enough, and specific advice to avoid fried and high fat foods to reduce gastrointestinal side effects. Our protein floor and fat cap follow this guidance.
Nutritional priorities to support GLP-1 therapy for obesity · Joint advisory from the American College of Lifestyle Medicine, American Society for Nutrition, Obesity Medicine Association and The Obesity Society, 2025
Recommends nutrient dense, minimally processed foods during GLP-1 therapy and advises avoiding refined sugars and sugar sweetened products. Our sugar cap follows this guidance.
A Systematic Review of the Effects of Polyols on Gastrointestinal Health · Lenhart & Chey, Advances in Nutrition, 2017
Sugar alcohols cause flatulence, abdominal discomfort and laxative effects that scale with dose, and malabsorption increases when polyols are combined. This is why bars containing maltitol and similar polyols are marked on our lists.
A digestive tolerance study of maltitol · Ruskoné-Fourmestraux et al., European Journal of Clinical Nutrition, 2003
Maltitol caused more frequent diarrhea than sugar, though mainly at high daily doses around 90g, far more than a single bar contains. Individual sensitivity varies widely, which is why we mark these bars rather than exclude them.
Tolerance of maltitol in milk chocolate at two dose levels · Storey et al., Journal of Nutrition, 1998
In healthy young adults, 30g of maltitol caused no significant symptoms versus sugar and 40g caused only mild gas. A single protein bar contains well below these doses, which is why the maltitol mark is a heads up for sensitive people, not a warning for everyone.
Regulation (EU) No 1169/2011, Annex III · European Union food information law
EU law requires foods with more than 10% added polyols to carry the warning "excessive consumption may produce laxative effects".
Slow and fast dietary proteins differently modulate postprandial protein accretion · Boirie et al., PNAS, 1997
The original "fast vs slow protein" study: whey produces a rapid rise in blood amino acids while casein digests slowly, partly because it slows gastric emptying. It does not show casein is harmful; over 7 hours casein actually produced a better net protein balance.
Whey hydrolysate, casein, or soy protein and muscle protein synthesis · Tang et al., Journal of Applied Physiology, 2009
Whey produced a roughly 93% larger immediate muscle protein synthesis response than casein at rest. This is why whey based products are prioritised when portions are small, not because casein is a poor protein.