Radical Health · On GLP-1 · Protein on a GLP-1
The number, and how to hit it

How much protein on a GLP-1?

On Ozempic, Wegovy, Mounjaro or Zepbound, appetite drops — so protein, the macro that protects your muscle, is the first thing to slip. Here's the number, why it's set that way, and how to hit it. Or skip ahead to the protein calculator.

GLP-1 medications work largely by turning down appetite. That's the point — but it has a side effect most food-tracking apps miss: when you eat less of everything, you eat less protein too. And protein is exactly the macronutrient you can least afford to lose, because it's what defends your muscle while the fat comes off.

This page gives you a practical number, explains why it's set against your goal weight rather than your current weight, breaks it down per meal, and lists honest, easy ways to hit it on the days you're barely hungry. Everything here is graded the way researchers grade it — kept only if it survived a deliberate attempt to refute it.

Skip to your number

The number, plainly

Floor 1.6.
Target 2.0.

For most people losing weight on a GLP-1, aim for a daily protein floor of about 1.6 g per kg of your goal weight, and a target of about 2.0 g per kg of goal weight. If you're an older adult, lean toward the upper end — roughly 2.1–2.2 g/kg — because ageing muscle needs a bigger push to respond.

Why goal weight and not what the scale says today? Because protein need tracks your lean (fat-free) mass, not your fat mass. If you're carrying excess fat, basing protein on current weight over-states the number — you'd be feeding muscle you don't have. Goal weight is a simple, no-scan stand-in for a lean-mass target. As a rough adherence anchor, that lands many people somewhere around 80–120 g/day. Get your exact number →

What it's based on

The graded
evidence.

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, sets an absolute floor of ~0.4–0.5 g/kg/day below which atrophy risk rises, and offers ~80–120 g/day as a practical adherence anchor. It also notes that protein alone is "likely inadequate" without resistance training.[1]
Strong · position stand
1.4–2.0 g/kg/day supports muscle for active people; ~2.3–3.1 g/kg of fat-free mass for lean people cutting. The ISSN position stands place our floor and target comfortably 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 protein harder to hit, which is exactly why it matters more, not less.[4]
Moderate · older adults
Over 50, aim higher and target ~25–40 g protein per meal (~3 g leucine). Anabolic resistance means older muscle needs a bigger per-meal dose to respond, and higher protein during weight loss preserves more lean mass.[5, 6]
In progress
A dedicated GLP-1 muscle-preservation trial uses 1.6 g/kg/day plus resistance training. The LEAN-PREP RCT pairs that protein dose with lifting during GLP-1 treatment. Results are not yet reported — we cite it as design intent, not as proof.[7]
When you're not hungry

How to actually
hit it.

The number is the easy part. The hard part is getting it in when the medication has quietly switched your appetite off. These five habits do most of the work.

Front-load it early

Appetite tends to be best soon after a dose wears off and earlier in the day. Eat your biggest protein hit while you still can, before the window closes.

Protein first at every meal

Build the plate around the protein and eat it before the carbs and veg. If you fill up early — and you will — the part that protects muscle is already in.

Aim for 25–40 g per meal

There's a per-meal threshold that actually triggers muscle protein synthesis. Spreading protein across meals beats one giant steak at dinner — over 50, aim at the top of that range.

Lean on dense, easy options

Greek yogurt, eggs, fish, lean meat, tofu, cottage cheese — and a protein shake when solid food feels like too much. High protein per bite, low effort to eat.

Spread it across the day

Because of the per-meal threshold, three or four protein-anchored eating moments do more than two. Small and frequent beats large and rare when appetite is low.

Pair it with a little lifting

Protein defends muscle; resistance work defends it further. Two short, gentle strength sessions a week make the protein you do eat go further.

⚠︎

This is an estimate, not medical advice

These numbers are an informational guide, not a diagnosis, prescription, or substitute for your clinician. Your GLP-1 dose and plan are between you and your prescriber — show them your protein target so they can sanity-check it for you, ideally with a dietitian.

Protein is generally safe with healthy kidneys; existing kidney disease changes that and may require limits. 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 many grams of protein per day on a GLP-1? +
A practical target 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). As an easy anchor, many people aim for roughly 80–120 g/day. Because a GLP-1 suppresses intake of every macro, protein gets harder to hit and matters more, not less. Get your exact number →
Should protein be based on my current or goal weight? +
Use your goal (or lean) weight, not your current weight. Protein needs track lean mass, not fat mass, so 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 a body scan.
Why is protein so important on these medications? +
Protein is the macro that defends muscle as you lose weight — in a deficit it preserves lean mass rather than building it. The catch on a GLP-1 is that appetite suppression cuts how much you eat of everything, protein included, so it becomes both harder to hit and more important. It works best paired with a little resistance training. How to keep the muscle →
Can too much protein be harmful? +
For people with healthy kidneys, the intakes discussed here (~1.6–2.0 g/kg of goal weight) are generally considered safe. Existing kidney disease changes that — protein may need to be limited and managed with a clinician. If you have, or might have, kidney disease, talk to your doctor or a renal dietitian before raising your protein.
What if I can't eat enough food at all? +
Prioritise protein within whatever you can manage — make it the first thing on the plate and lean on dense, easy options like Greek yogurt, eggs, fish, lean meat, tofu, or a shake. Try not to drop below an absolute floor of about 0.4–0.5 g/kg per day. If you genuinely can't eat enough for more than a short stretch, tell your prescriber or dietitian.
References

The sources.

  1. Multi-society advisory on nutrition & muscle during weight loss. 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 (RCT). Nature Medicine 2025. PMC12443625
  5. Bauer J et al. PROT-AGE protein recommendations for older people. JAMDA 2013. PMID 23867520
  6. Kim JE et al. Higher protein preserves lean mass during weight loss in older adults (meta-analysis). Nutr Rev 2016. PMC4892287
  7. LEAN-PREP RCT (protein + resistance training during GLP-1). NCT06885736
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