Radical Health · On GLP-1 · Protein calculator
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GLP-1 protein calculator.

On Ozempic, Wegovy, Mounjaro or Zepbound, the risk flips from eating too much to eating too little — and protein is the first thing to slip. Enter your numbers to get a daily protein floor and target to protect the muscle you'd otherwise lose. Nothing you type leaves this page.

Your details

I'm on a GLP-1 medication
Ozempic, Wegovy, Mounjaro, Zepbound…
Your daily protein floor
115g/day
The minimum — hit this every single day to defend muscle.
1.6 g/kg × 72 kg goal weight
Protein target
144g
The muscle-protection aim (≈2.0 g/kg goal weight).
Per meal (×4)
36g
Aim for 25–40 g of protein per meal.
Calorie floor
1500kcal
A planning estimate — don't routinely eat below this.
Maintenance ≈
2100kcal
A gentle deficit lands near 1700 kcal.
⚠︎

On a GLP-1, protein is the priority, not the deficit. Appetite suppression cuts how much you eat of everything — so hitting the floor is the win. Never drop below an absolute floor of about 48 g/day.

Estimates only — not medical advice, and not a substitute for your prescriber or dietitian. Protein is based on goal weight; calories use the Mifflin–St Jeor equation, which is an approximation. See the math →

How the number is built

Three honest
steps.

STEP 01

Protein from goal weight

We multiply your goal weight by ~1.6 g/kg for the floor and ~2.0 g/kg for the target. Goal weight — not current weight — because protein need tracks lean mass, and current weight over-states it when you're carrying excess fat.

STEP 02

A calorie floor, not just a cap

We estimate maintenance with Mifflin–St Jeor and your activity, then set a floor you shouldn't routinely eat under. On a GLP-1 the danger is under-eating, so the floor matters more than the ceiling.

STEP 03

Split it so it's doable

We divide protein across your meals, because there's a per-meal threshold (~25–40 g, more if you're over 50) that actually triggers muscle protein synthesis. One giant steak at dinner doesn't do the same job.

What it's based on

The graded
evidence.

The same standard as the rest of the site: each claim graded the way researchers grade it, kept only if it survived a deliberate attempt to refute it.

Expert consensus
~1.2–1.6 g/kg/day during active weight loss on a GLP-1 — or ~1.5 g/kg of lean mass. A 2025 multi-society advisory recommends this range, notes that actual body weight overstates needs in obesity, and sets an absolute floor of ~0.4–0.5 g/kg/day below which atrophy risk rises. Protein alone is "likely inadequate" without resistance training.[1]
Strong · position stand
1.4–2.0 g/kg/day supports muscle for most active people; ~2.3–3.1 g/kg of fat-free mass when cutting. The ISSN position stands place our floor and target inside the evidence-supported range.[2, 3]
Moderate · RCT
A GLP-1 cuts intake of every macro — protein included. In a randomized trial, tirzepatide lowered intake of fat, carbohydrate and protein. So appetite suppression makes hitting protein harder, which is exactly why a floor matters more, not less.[4]
Strong · meta-analysis
Resistance training prevents ~93.5% of the lean mass you'd lose in a deficit. Protein protects muscle; lifting protects it further. Note the honest limit: in a deficit this preserves muscle — it doesn't build it.[5]
Moderate · DXA substudies
~25–40% of GLP-1 weight loss is lean mass — similar to diet alone, with muscle quality preserved. The fix is defending the absolute amount of muscle with protein and lifting, not fearing the drug.[6, 7]
Moderate · older adults
Over 50, aim for the higher end and ~25–40 g protein per meal. Anabolic resistance means older muscle needs a bigger per-meal dose (~3 g leucine) to respond. Higher protein during weight loss preserves more lean mass.[8, 9]
⚠︎

This is an estimate, not medical advice

This calculator is an informational tool, not a diagnosis, prescription, or substitute for your clinician. Your GLP-1 dose and plan are between you and your prescriber — show them the targets so they can sanity-check them for you.

Protein is generally safe with healthy kidneys; existing kidney disease changes that. Seek care for dizziness, fainting, chest pain, persistent nausea or vomiting, or any thoughts of disordered eating.

Protein on a GLP-1

Straight answers.

How much protein should I eat on a GLP-1? +
A practical range is about 1.6–2.0 g per kg of your goal weight per day, with the lower end as a daily floor. The 2025 multi-society advisory frames it as ~1.2–1.6 g/kg of current weight during active weight loss (or ~1.5 g/kg of lean mass), with an absolute floor of ~0.4–0.5 g/kg. Because a GLP-1 suppresses intake of every macro, protein gets harder to hit and matters more, not less. Full guide →
Why goal weight, not my current weight? +
Protein needs track lean mass, not fat mass. If you're carrying excess fat, current weight over-states the number — the advisory says so directly and prefers lean-mass-based targets. Goal weight is a simple stand-in for a lean-mass target without needing a body scan.
Will I lose muscle on Ozempic or Mounjaro? +
Some lean mass goes with the fat — DXA substudies put it around 25–40% of total weight lost, similar to dieting, with muscle quality generally preserved. The fix is defending the absolute amount with protein and a little lifting (which prevents ~93.5% of deficit muscle loss). We never call these drugs "muscle-wasting." How to keep the muscle →
How do I hit protein when I'm barely hungry? +
Front-load it early before appetite fades, build each meal around protein first, aim for ~25–40 g per meal, and lean on dense, easy options — Greek yogurt, eggs, fish, lean meat, tofu, or a shake when solid food feels like too much.
Is anything I type saved or sent anywhere? +
No. The whole calculator runs in your browser. Nothing is uploaded, stored, or shared — close the tab and it's gone.
References

The sources.

  1. Multi-society advisory on nutrition & muscle during weight loss (incl. GLP-1). Am J Lifestyle Med 2025. PMC12125019
  2. Jäger R et al. ISSN Position Stand: protein and exercise. J Int Soc Sports Nutr 2017. PMC5477153
  3. Aragon AA et al. ISSN Position Stand: diets & body composition. J Int Soc Sports Nutr 2017. PMC5470183
  4. Tirzepatide reduces intake of all macronutrients incl. protein (RCT). Nature Medicine 2025. PMC12443625
  5. Sardeli AV et al. Resistance training preserves lean mass during calorie restriction (meta-analysis). Nutrients 2018. PMC5946208
  6. SURMOUNT-1 DXA body-composition substudy (tirzepatide). Diabetes Obes Metab 2025. PMC11965027
  7. Neeland IJ et al. Body-composition changes with incretin therapies (review). Diabetes Obes Metab 2024. doi:10.1111/dom.15728
  8. Bauer J et al. PROT-AGE: protein intake in older people (position paper). JAMDA 2013. PMID 23867520
  9. Kim JE et al. Higher protein preserves lean mass during weight loss in older adults (meta-analysis). Nutr Rev 2016. PMC4892287
Keep reading

Related guides.

GUIDE

How much protein on Ozempic, Wegovy & Mounjaro

The numbers, the reasoning, and how to actually hit them.
GUIDE

How to avoid muscle loss on a GLP-1

Protein plus a little lifting — the two defences that work.
PRODUCT

Radical Fat Loss on a GLP-1

A dedicated on-medication mode that guards protein for you.

Keep the muscle.
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Radical Fat Loss does this math for you every day — and guards your protein while your appetite is low. Pre-launch; join the early list for one email at launch.

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