Investigational · not FDA approved

Editorially reviewed · Last updated July 2026 · How we review

Protein Target Calculator for Retatrutide

Key findings

Target ~1.5 g protein per kg lean mass when you know body fat %; otherwise use 1.2–1.6 g/kg adjusted body weight (calculator default) or the 80–120 g/day absolute band.
Formula is always shown under your result — lean-mass path or ABW path, no black box.
When appetite is broken: shakes, grazing, mechanical eating, protein first — not perfect plates.
Protein without resistance training is not enough; the joint advisory pairs the floor with strength work ≥3×/week.
No dose milligrams on this page — phase language only (weeks 1–3 / escalation / maintenance).

Protein Target Calculator for Retatrutide

When food noise drops on reta, the hard part is not “eating clean” — it is getting enough protein in when appetite is broken. This tool turns your weight (and optional body fat %) into a daily protein target using the 2025 joint advisory for people on GLP-1 therapy.

For the full operational playbook — shot-day soft foods, grocery list, fiber ramp, under-eating safety — see What to Eat on Reta. Soft high-protein assemblies live in reta-friendly recipes. For lean-mass context from the trials, see muscle loss on retatrutide.

Daily protein target

Enter your weight. If you know body fat %, open that field for a lean-mass target; otherwise we use the adjusted-body-weight path from the advisory.

Your protein target

Weight in, daily protein out — grounded in the 2025 joint advisory for people on GLP-1 therapy. No dose math here; just how much protein to aim for when appetite is quiet.

Weight

134g

protein per day

101–134 g

range

~34 g × 4

per-meal split

≈ 3 shakes + 2 small meals

when appetite is broken

1.6 g × 83.9 kg adjusted body weight = 134 g

Lean mass unknown — using current weight as the adjusted-body-weight estimate (1.2–1.6 g/kg during active loss). Most adults also land near 80–120 g/day absolute. Body-fat % gives a tighter lean-mass target.

Disclaimer: This calculator is for general education from published nutrition guidance. It is not medical advice and does not replace a clinician or registered dietitian. Individual protein needs vary with kidney function, training load, and total intake.

How to actually hit this number

Appetite on reta is not a reliable timer. Hunger often never shows up, especially around shot day and the day after. Treat the gram number above as a floor to hit with liquids and small plates, not a meal-prep aesthetic.

When solid food fails:

Ready-to-drink high-protein milk (Fairlife-class or similar) — dense protein, small volume
Whey or casein mixed thin (easier when the stomach is slow)
Greek yogurt blended with a little fruit or ice
Bone broth with a scoop of unflavored whey or collagen stirred in

Mechanical habits that still work when food noise is gone:

Grazing — small protein hits every few hours instead of three “real meals”
Mechanical eating — eat on a timer even when you are not hungry
Protein first — whatever you open, finish the protein portion before carbs or fat
Girl dinner — cottage cheese, deli turkey, eggs, crackers, fruit counts if the protein adds up

If you literally cannot get food down for days after a pin, that is a titration signal — hold a phase longer or talk to your prescriber. Do not power through starvation to “keep going up.” Phase language only here: weeks 1–3, escalation, maintenance — no milligram chase.

More lists and the under-eating safety block live on the what to eat on reta hub.

Dense protein sources (small volume)

Food	Serving	Protein	Calories
Greek yogurt (nonfat)	1 cup (245g)	20g	100
Cottage cheese (low-fat)	1 cup (226g)	28g	183
Chicken breast (cooked)	100g	31g	165
Eggs	2 large	12g	143
Canned tuna	1 can (142g)	33g	150
Whey protein shake	1 scoop (30g)	24g	120
Salmon (cooked)	100g	25g	208
Lentils (cooked)	1 cup (198g)	18g	230

Editorial brand names are examples only. No buy links.

What the formula is based on

A 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society sets the frame for people on GLP-1-class drugs:

Best target when you know composition: about 1.5 g protein per kg of lean (fat-free) mass per day
If you do not know lean mass: 80–120 g protein per day for most adults is the absolute band; during active weight loss the advisory also cites 1.2–1.6 g per kg adjusted body weight
Floor you should not live under: roughly 0.4–0.5 g/kg/day
Protein alone is not enough — the same advisory pairs targets with resistance training at least three times per week

The calculator shows the formula under your result. When body fat % is entered, lean mass = weight × (1 − body fat fraction), then 1.5 g/kg lean mass. When body fat is unknown, current scale weight is used as the adjusted-body-weight estimate and the primary number is the upper end of 1.2–1.6 g/kg (1.6 g × kg).

There is still no published food-intake study inside retatrutide trial arms. Class guidance plus mechanism is the evidence base — same posture as the diet hub research section.

Why protein first on reta

Class food-record studies find average intakes near 750 calories and about 33 g protein/day in multi-hundred-person samples — far below what preserves lean mass. Higher protein predicted more weight-loss success in one dual-agonist diary study, not less. Retatrutide’s triple agonism (including glucagon) can make under-eating easier, not harder; protecting lean mass is the job, not winning a restriction contest.

See also: Does retatrutide cause muscle loss? for the DXA / body-composition context.

Frequently Asked Questions

How much protein should I eat per day on retatrutide?

Use the calculator above. The 2025 joint advisory frame is about 1.5 g per kg lean mass when you know body composition, or 80–120 g/day absolute for most adults if you do not. During active weight loss, 1.2–1.6 g per kg adjusted body weight is the active-loss band. Do not live under roughly 0.4–0.5 g/kg/day. Pair protein with resistance training at least 3×/week.

Why does the calculator ask for body fat %?

Lean mass (fat-free mass) is a better basis than total scale weight for people with higher body fat — total weight overestimates protein need relative to the tissue you are trying to keep. If you know body fat from a DEXA, smart scale, or calipers, open that field. If you do not, the adjusted-body-weight path still gives a usable target.

What is adjusted body weight here?

In the advisory, active weight-loss protein is expressed per kg of adjusted body weight. Without height and a full clinical IBW calculation, this tool uses your current scale weight as that estimate and shows the formula openly. Entering body fat % switches to the preferred lean-mass path (1.5 g/kg FFM).

How do I hit 100 g of protein when I can barely eat?

Liquids first: two Fairlife-class RTDs or whey shakes can cover ~50–60 g. Add Greek yogurt, cottage cheese, eggs, or tuna in small hits through the day. Grazing and mechanical eating beat waiting for hunger. Full tactics sit on the protein when you can't eat section of the diet hub.

Does higher protein stop muscle loss on retatrutide?

It helps; it is not a guarantee. All meaningful weight loss includes some lean-mass loss. The joint advisory is explicit that protein without structured resistance training is likely inadequate. Aim for strength work ≥3×/week plus the protein floor. Trial DXA context: muscle loss.

Should my protein target change by dose phase?

The gram target is about your body and training, not the milligrams on the syringe. What changes by phase is how hard it is to hit the number: weeks 1–3 are for learning which high-protein foods you tolerate; escalation often needs more shakes and soft plates; maintenance is keeping the floor without sliding into chronic under-eating. No mg numbers on this page — phase language only.

Sources

Mozaffarian, D., et al. (2025). Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society. Obesity Pillars / multi-journal co-publication. PMC12264624.
Johnson, B., et al. (2025). Nutrient intake in adults on a GLP-1 receptor agonist. Frontiers in Nutrition. DOI: 10.3389/fnut.2025.1566498.
Dietary intake on GLP-1/GIP agonists (2025). Research Square preprint. DOI: 10.21203/rs.3.rs-7640335/v1.
Jastreboff, A.M., et al. (2023). Triple-Hormone-Receptor Agonist Retatrutide for Obesity. NEJM. DOI: 10.1056/NEJMoa2301972.

How we keep this honest

What this is: Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
Regulatory status: Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
Our standard: Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
No commercial ties: We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.

Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Sources

Reta-friendly recipes
glp3.wiki
2025 joint advisory on nutrition with GLP-1 therapy
Obesity Pillars / PMC
GLP-1 RA nutrient intake study
Frontiers in Nutrition
Phase 2 trial (NEJM)
New England Journal of Medicine

Grounded in primary sources

NEJM

The Lancet

JAMA

FDA

ClinicalTrials.gov

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