How Many Calories Should I Eat on Retatrutide?
How many calories should I eat on retatrutide is a question the trials never answered with a number. The 2023 phase 2 trial did not set a calorie deficit, and the TRIUMPH trials chose healthy food over calorie cuts on purpose.
The short answer
- No official calorie target exists. Retatrutide has no approved label, and its trials gave food counselling, not a calorie number.
- Your burn can be estimated. The Mifflin-St Jeor equation plus an activity multiplier gives a rough daily figure.
- Eating too little has costs. A GLP-1 nutrition advisory flags missing nutrients below about 1,200 calories a day for women and 1,800 for men.
- Want your own figures? The calculator below estimates your burn, protein, fat and carbs from your sex, age, height, weight and activity.
We read the US top 10 for this search on 22 October 2026. It is mostly dosage guides, meal-plan posts and Facebook threads. The two dosage guides we read in full say nothing about calories. None of the results quotes what the retatrutide trial protocols actually told people to eat. That is where this page starts.
Sources: Phase 2 trial full text, Methods and Table 3 (NEJM, doi 10.1056/NEJMoa2301972); TRIUMPH trial design paper, full text (PMC12673447); US top 10 for "how many calories should i eat on retatrutide" and "retatrutide calorie deficit", checked 22 October 2026
Retatrutide calorie and macro calculator
Put in your own sex, age, height, weight and activity. This runs the same resting burn formula and activity factors shown above, then estimates a protein, fat and carb split. It is a learning tool, not a prescription, and it updates as you type.
BMI
29.4
Overweight
Resting burn
1,799
kcal at rest
Daily burn
2,788
kcal a day
Target, maintenance
2,788
kcal a day
Protein
108 g a day
at 1.2 g per kg of body weight
Fat
62 to 108 g
20 to 35 percent of calories
Carbs
345 to 450 g
the calories left after protein and fat
These results are rough estimates from published equations, shared for learning. They are not a meal plan, a promise of weight loss, or medical advice. A doctor or dietitian who knows your health sets the real target.
Sources: Mifflin and St Jeor equation, Am J Clin Nutr 1990 (PMID 2305711); Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127); Institute of Medicine, Dietary Reference Intakes for macronutrients (2005); CDC, adult BMI categories (read 22 October 2026); Phase 2 trial full text, Methods and Table 3 (NEJM, doi 10.1056/NEJMoa2301972)
What did the retatrutide trials tell people to eat?
Both trial programs paired the weekly shot with lifestyle counselling. Neither one handed out a calorie number.
| Trial | Food | Activity |
|---|---|---|
| Phase 2, 48 weeks (NEJM 2023) | Regular counselling from a dietitian or other qualified health worker, based on the US dietary guidelines. The protocol did not require any set energy deficit. | Counselling based on the US physical activity guidelines. |
| TRIUMPH phase 3 (2026) | Counselling tailored to each person. It stresses what is on the plate, not cutting calories: a balanced mix of protein, carbs and fat, nutrient-rich foods, and eating enough. | At least 150 minutes a week of moderate activity, including some muscle strengthening. |
TRIUMPH also had a guard against losing too much. Its design paper lets a person's dose be lowered once their BMI reaches 22 or less, or if they feel their weight loss has gone too far. In the phase 2 trial, 14 people dropped to a BMI of 22 or lower, and 8 on retatrutide had their dose cut by the protocol for that reason.
So a trial participant was never told to eat, say, 1,500 calories. They were taught to eat well and move more.
Sources: Phase 2 trial full text, Methods and Table 3 (NEJM, doi 10.1056/NEJMoa2301972); TRIUMPH trial design paper, full text (PMC12673447)
Where does the 500 calorie deficit come from?
The figure is common online. One GLP-1 diet post in this search's top 10 calls a cut of about 500 calories a day below your burn typical in clinical trials. That matches an older trial style. The TRIUMPH design paper says most earlier obesity drug trials used calorie-reduced diets as the background plan.
TRIUMPH broke from that. Its authors say they followed newer guidance on lifestyle support for people taking strong weight loss drugs. A 2025 advisory from four obesity and nutrition groups helps explain why: people on GLP-1 drugs have been seen eating 16% to 39% fewer calories. Retatrutide acts on the GLP-1 receptor plus two others, though the advisory's figures come from GLP-1 drug studies, not from retatrutide.
Sources: trimrx.com, How Many Calories Should You Eat on GLP-1 Medications? (read 22 October 2026); TRIUMPH trial design paper, full text (PMC12673447); Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127)
How is a daily calorie need estimated?
The usual first step is your resting burn: the energy your body uses at rest. The Mifflin-St Jeor equation from 1990 predicts it from weight, height and age. It was built from measurements in 498 healthy adults, both normal weight and obese.
- Men: 10 x weight in kg, plus 6.25 x height in cm, minus 5 x age, plus 5.
- Women: the same sum, minus 161 instead of plus 5.
Then the resting figure is multiplied by an activity factor to estimate the whole day. These are the five factors our calculator uses. They are rough guides, and the equation itself gives a prediction, not a measured burn.
| Sedentary | Light | Moderate | Active | Very active |
|---|---|---|---|---|
| x 1.2 | x 1.375 | x 1.55 | x 1.725 | x 1.9 |
Our retatrutide calculator runs this same math on your own height, weight and age. It then lets you set a calorie target and projects a timeline from it.
Sources: Mifflin and St Jeor equation, Am J Clin Nutr 1990 (PMID 2305711)
Worked example: three made-up people
Here is the method run for three example adults. Their resting burns come out at 1,620, 1,993 and 1,247 calories a day.
| Example person | Sedentary | Light | Moderate | Active | Very active |
|---|---|---|---|---|---|
| Woman, 40, 165 cm, 95 kg | 1,944 | 2,228 | 2,511 | 2,795 | 3,078 |
| Man, 45, 178 cm, 110 kg | 2,391 | 2,740 | 3,088 | 3,437 | 3,786 |
| Woman, 60, 158 cm, 72 kg | 1,496 | 1,714 | 1,932 | 2,150 | 2,368 |
Now compare a fixed 500 calorie cut with the 16% to 39% drop in eating that the advisory reports on GLP-1 drugs, assuming each person now eats about what they burn. The last column is the advisory's line below which vitamins and minerals are more likely to run short. This uses the sedentary row.
| Example person | Daily burn | 500 less | 16% less | 39% less | Nutrient line |
|---|---|---|---|---|---|
| Woman, 40, 165 cm, 95 kg | 1,944 | 1,444 | 1,633 | 1,186 (under the line) | 1,200 |
| Man, 45, 178 cm, 110 kg | 2,391 | 1,891 | 2,008 | 1,459 (under the line) | 1,800 |
| Woman, 60, 158 cm, 72 kg | 1,496 | 996 (under the line) | 1,257 | 913 (under the line) | 1,200 |
Two things stand out. For the smaller, older woman, a flat 500 calorie cut alone lands at 996, under her 1,200 line. And at the high end of the appetite drop, all three people fall under their line with no planned cut at all; the man would eat about 1,459. A fixed rule taken from older trials does not fit everyone the same way.
Disclaimer: these numbers show how an estimate is worked out for made-up example people. They are not a calorie or protein target for you. A doctor or dietitian who knows your health should set one.
Sources: Mifflin and St Jeor equation, Am J Clin Nutr 1990 (PMID 2305711); Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127)
How much protein on retatrutide?
No retatrutide paper gives a protein number. The 2025 joint advisory on GLP-1 drugs is the closest guide. It reports these figures:
- 0.8 g per kg of body weight a day is the standard adult allowance, now under review.
- 1.2 to 1.6 g per kg a day has been put forward for people who are actively losing weight.
- Going under 0.4 to 0.5 g per kg can waste muscle, and staying at 2 g per kg or more for a long time should be avoided.
- A flat 80 to 120 g a day can be simpler to stick to.
There is a catch for people with obesity. The advisory says basing protein on full body weight can overstate the need by a lot, and experts have not agreed on a better base. Here are the plain per-kg numbers for the three example people, using their full weight:
| Example person | 0.8 g/kg | 1.2 g/kg | 1.6 g/kg |
|---|---|---|---|
| Woman, 40, 165 cm, 95 kg | 76 g | 114 g | 152 g |
| Man, 45, 178 cm, 110 kg | 88 g | 132 g | 176 g |
| Woman, 60, 158 cm, 72 kg | 58 g | 86 g | 115 g |
At 1.6 g per kg, the 110 kg man lands at 176 g, well past the 80 to 120 g fixed range. That is the kind of overstatement the advisory warns about. For which foods pack protein into small meals, see GLP-1 meals.
Disclaimer: these numbers show how an estimate is worked out for made-up example people. They are not a calorie or protein target for you. A doctor or dietitian who knows your health should set one.
Sources: Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127)
Why does eating too little matter?
- Muscle and lean mass. Fast weight loss takes some lean tissue with the fat. In the STEP 1 semaglutide trial, 38% of the weight lost was lean mass, the advisory notes. It adds that how hard calories are cut, how fast weight drops and whether you strength train all change how much lean mass goes.
- Missing nutrients. Below about 1,200 calories a day for women and 1,800 for men, the advisory says vitamins and minerals often fall short. It names iron, calcium, magnesium, zinc and several vitamins.
- Gallstones. NIDDK says losing weight very quickly may raise the chance of gallstones, and slower loss may lower it. The advisory lists gallbladder disease as a rare side effect of GLP-1 drugs. In the retatrutide phase 2 trial, 3 people on the drug had a gallbladder or bile duct event (2 with gallstones, 1 with an inflamed gallbladder), against none on placebo.
- Fluids. The advisory says kidney problems reported after GLP-1 drugs reached the market seem tied to dehydration from nausea and vomiting.
Low appetite and nausea are part of why intake drops. The phase 2 trial counted them like this:
The 2023 phase 2 retatrutide trial reported these rates over 48 weeks:
Nausea: 45% on 12 mg once weekly, against 11% on placebo
Decreased appetite: 29% on 12 mg, against 9% on placebo
Disclaimer: these are once-weekly doses and average results from monitored clinical trials. They are shown to report what the studies found, not as advice to take any amount or as a promise of any result. Retatrutide has no approved dose.
The paper says stomach side effects came mostly while the dose was being raised, and were mostly mild to moderate. For ways to handle them, see managing GLP-1 side effects.
Sources: Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127); NIDDK, Dieting and Gallstones; Phase 2 trial full text, Methods and Table 3 (NEJM, doi 10.1056/NEJMoa2301972)
What weight change did the retatrutide trials report?
These are averages from people eating under trial counselling, not a forecast for anyone.
The published trials reported these average weight changes:
TRIUMPH-1 (80 weeks): -17.6% on 4 mg, -23.7% on 9 mg and -25.0% on 12 mg, against -3.9% on placebo
Phase 2 (48 weeks): -24.2% on 12 mg, against -2.1% on placebo
Disclaimer: these are once-weekly doses and average results from monitored clinical trials. They are shown to report what the studies found, not as advice to take any amount or as a promise of any result. Retatrutide has no approved dose.
For how each dose was reached step by step, see the retatrutide dosage guide. Retatrutide is still investigational. Eli Lilly's stated plan is to seek US approval early in 2027.
Sources: TRIUMPH-1 results, NEJM, online 29 Sep 2026 (PMID 42814954); Retatrutide phase 2 obesity trial, NEJM 2023 (PMID 37366315); Lilly news release on TRIUMPH-2 and the planned 2027 filing (29 Sep 2026)
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Common questions
How many calories should I eat on retatrutide?+
No published source gives a number. The 2023 phase 2 trial did not require a set calorie deficit, and the TRIUMPH trials counsel healthy food rather than calorie cuts. A calorie need can be estimated with the Mifflin-St Jeor equation and an activity multiplier, but the target itself is for a doctor or dietitian to set.
Did the retatrutide trials use a 500 calorie deficit?+
No. The phase 2 paper says its protocol did not require a specific energy deficit. The TRIUMPH design paper says its counselling focuses on food quality rather than calorie restriction, unlike most earlier obesity drug trials. The 500 calorie figure seen online matches that older trial style, not retatrutide.
How much protein should I eat on retatrutide?+
There is no retatrutide-specific figure. A 2025 joint advisory on GLP-1 drugs lists the adult allowance of 0.8 g per kg a day, notes that 1.2 to 1.6 g per kg has been put forward while losing weight, and gives 80 to 120 g a day as a simple fixed target. It warns that using full body weight can overstate the need in people with obesity.
Is it bad to eat too little on retatrutide?+
The sources name real risks. The GLP-1 advisory says vitamins and minerals often fall short below about 1,200 calories a day for women and 1,800 for men, and that a hard calorie cut can add to lean mass loss. NIDDK says losing weight very fast can raise the chance of gallstones.
How many macros should I eat on retatrutide?+
There is no retatrutide macro target in any trial. The calculator on this page gives a rough split from your own numbers: protein from the GLP-1 advisory per-kg figures, fat across the 20 to 35 percent band in the 2005 Dietary Reference Intakes, and the calories left over as carbs, with a flag when those carbs slip under the 130 g adult allowance. It is a study aid, and your own split belongs with a doctor or dietitian.
How much weight will I lose on retatrutide?+
No one can say for one person. In TRIUMPH-1, the average change at 80 weeks was -17.6% on 4 mg, -23.7% on 9 mg and -25.0% on 12 mg, against -3.9% on placebo. Those are group averages under trial care. Disclaimer: these are once-weekly doses and average results from monitored clinical trials. They are shown to report what the studies found, not as advice to take any amount or as a promise of any result. Retatrutide has no approved dose.
Do I need to exercise on retatrutide?+
In the TRIUMPH trials everyone was counselled to do at least 150 minutes of moderate activity a week, with some muscle strengthening. The joint advisory says protein alone is unlikely to protect muscle without strength training.
Sources: Phase 2 trial full text, Methods and Table 3 (NEJM, doi 10.1056/NEJMoa2301972); TRIUMPH trial design paper, full text (PMC12673447); Joint nutrition advisory for GLP-1 therapy, Obesity 2025 (PMID 40445127); NIDDK, Dieting and Gallstones; TRIUMPH-1 results, NEJM, online 29 Sep 2026 (PMID 42814954)
Related reading
Peptides Vietnam wrote this page to report what retatrutide studies and nutrition groups have published about eating. It is general education, not medical or diet advice, and it sets no calorie or protein target for any reader. No regulator has approved retatrutide yet.