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What to Eat on Reta: Protein, Shot Day & When You Can't Eat

Part of How-To Guides.

Key findings

  • Hit a protein floor first — roughly 80–120 g/day for most adults, or ~1.5 g per kg lean mass when you know it — with shakes and mechanical eating when solid food fails.
  • Shot day (and the day after): soft, low-fat, small plates; skip fried food, huge volumes, and raw fiber piles.
  • Ramp fiber with water — dumping salad or full-dose psyllium into a slowed gut is the constipation trap (fiber paradox).
  • Please eat: class research shows average intakes near 750 kcal and ~33 g protein; chronic under-eating costs muscle, hair, and energy.
  • The research covers food intake with GLP-1 treatment, glucagon and carbohydrates, and micronutrient gaps.

What to Eat on Retatrutide When Appetite Is Low

When appetite is low, getting enough protein and other nutrients can be difficult, especially around injection day.

This guide covers protein, food for injection days, groceries, fiber, alcohol, eating out, and signs of under-eating, with links to the supporting research.

For the science behind appetite changes, read how retatrutide works. For reported symptoms and safety concerns, see retatrutide side effects.
Retatrutide is investigational and not FDA-approved. Nothing here is medical advice. Work dietary changes with your prescriber or a registered dietitian.

Build the plate in order

Three parts. Start with protein.

  1. 01

    One protein

    Fish, eggs or dairy

  2. 02

    Soft carbs

    Rice, oats or banana

  3. 03

    Cooked veg

    A little, as tolerated

Try a different protein:
½ protein¼ carbs¼ vegetables

A rough guide to plate space, not a macro ratio or an amount you have to finish.

Only a few bites sound good?Try a small yogurt bowl

Plate example: salmon, rice and cooked vegetables.

Generated food images are illustrative. Adapt portions and foods to your needs with your clinician or dietitian.

Protein when you can't eat

Getting enough protein can be difficult when appetite is suppressed and gastric emptying is slow.

Protein targets

A 2025 joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society gives GLP-1 users a clear protein frame:

  • Best target: about 1.5 g protein per kg of lean body mass per day
  • If you don’t know lean mass: 80–120 g protein per day for most adults
  • During active weight loss: about 1.2–1.6 g per kg body weight (use adjusted body weight at higher BMIs so total weight does not overstate need)
  • Floor you should not live under: roughly 0.4–0.5 g/kg/day
  • Protein alone is not enough — the same advisory pairs this with resistance training at least three times per week (plus weekly aerobic activity)
Shakes, smaller meals, and eating at scheduled times can help when solid meals are difficult. The illustrated plate shows a protein-first approach; it is not a trial diet protocol.
Want a personal gram target from weight (and optional body fat %)? Use the interactive protein target calculator — lean-mass path or adjusted-body-weight path, formula shown under the result. For soft, high-protein assemblies (shot-day yogurt + whey and more), see the reta-friendly recipes.

Protein drinks when solid food is difficult

Protein drink options include:

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

This guide contains no affiliate links.

Grazing and mechanical eating

When appetite is low, it can be easy to forget to eat. People report using these approaches:

  • Grazing — small protein hits every few hours instead of three “real meals”
  • Mechanical eating — eat on a timer even when you are not hungry; hunger is not a reliable signal on reta
  • Protein first — whatever you open, eat the protein portion before carbs or fat
  • Girl dinner — a composed plate of small easy items (cottage cheese, deli turkey, berries, crackers) counts if the protein adds up

When eating becomes difficult

If you cannot eat for days after an injection, talk to your prescriber about how this affects treatment. Dose increases are gradual, and some people need to stay at a dose longer or reduce it when intake falls.

Dense protein sources (small volume)

Protein per shown portion · 0–40 g scale

  • Greek yogurt

    ¾ cup · 170 g

    Plain, nonfat

    18 g protein

    90 kcal

  • Cottage cheese

    ½ cup · 113 g

    Low-fat

    13 g protein

    90 kcal

  • Chicken breast

    100 g

    Cooked, skinless

    31 g protein

    165 kcal

  • Eggs

    2 eggs

    Large

    12 g protein

    140 kcal

  • Tuna

    1 can · 113 g drained

    Canned in water, drained

    20 g protein

    90 kcal

  • Whey shake

    1 scoop · about 30 g

    Mixed with water

    24 g protein

    120 kcal

  • Salmon

    100 g

    Atlantic, farmed, cooked

    22 g protein

    206 kcal

  • Lentils

    1 cup · 198 g

    Cooked

    18 g protein

    230 kcal

8 protein sources shown.

Approximate amounts; products and preparation vary. Portions differ between foods. Bars compare grams of protein, not progress toward a daily target. Images illustrate foods, not exact serving sizes.

Find your daily protein target
Nutrition sources & portions

These are label examples and USDA reference foods, rounded to whole grams and calories. Check your product’s label. Brand names identify the source, with no affiliate links.

Shot-day safe foods

Appetite and GI effects are often strongest in the 24–48 hours after a pin. Plan that window on purpose.
Shot day · soft plate
  • Greek yogurt or skyr (plain or lightly flavored)
  • Protein shake or Fairlife-class RTD — sip slowly
  • Bone broth or miso-style broth
  • Banana, applesauce, or ripe melon
  • Oatmeal or cream of rice (small bowl)
  • Scrambled eggs or egg bites (not fried hard)
  • White rice or toast if you need something starchy and bland
  • Cottage cheese, thinned with a splash of milk if thick texture bothers you
  • Ginger tea or crystallized ginger for nausea
  • Room-temperature or cool foods if heat worsens queasiness
Print this list · All free printables

Usually skip on pin day

  • Fried and high-fat meals (fat + slowed emptying = nausea)
  • Huge portions (volume is the enemy when the stomach is slow)
  • Carbonated drinks (bloating on top of delay)
  • Very spicy food
  • Big raw salads (raw fiber sits harder than cooked)
Anecdotally, some people eat a larger protein-forward meal the day before the pin and go light for a day or two after. That pattern matches weekly GLP-1 pharmacokinetics but has not been tested in a retatrutide trial.

First-shot grocery list

Stock this before your first pin so you are not deciding food while nauseous.

Your grocery checklist
0 of 16 checked

Check what you already have, then choose what you’ll eat. You don’t need every item. Includes three optional extras; checks last until you leave this page.

Fridge & freezer

Easy protein, ready when you are

Cupboard

Low-effort meals from a few staples

Soft sides

A little variety alongside protein

Optional extras to discuss with your clinician

Electrolytes, fiber supplements and vitamins depend on your intake and health needs. They aren’t a required shopping bundle.

Read the fiber guidance before adding psyllium
Print grocery list7-day plan one-pager

Fiber and constipation (the fiber paradox)

Reta slows the gut. Constipation is common. The trap: people hear “eat more fiber,” dump a huge salad or a mega scoop of psyllium on day one, and feel worse. That is the fiber paradox — you need fiber, but you have to ramp it, with water, while the gut is still adapting.

Fiber protocol · ramped, not dumped

The fiber paradox: too much, too fast, makes things worse

Increase fiber gradually. Adding large amounts of raw fiber or psyllium at once can worsen constipation.
Fiber protocol
  1. 1Start low. If you have been at ~10–15 g fiber, do not jump to 30 g overnight. Add one cooked fiber source first (oats, soft beans, steamed veg).
  2. 2Water is not optional. Fiber without fluid turns into a plug. Aim for steady sips all day — harder when you are barely eating.
  3. 3Prefer cooked over raw piles. Cooked vegetables and peeled fruit move more easily than giant raw salads on a slowed stomach.
  4. 4Psyllium: micro-dose first. A half-teaspoon in water, then titrate. Starting with the full label dose can be difficult to tolerate.
  5. 5Movement helps motility. Short walks after small meals beat lying still all afternoon.
  6. 6Know when to escalate care. No bowel movement for several days with pain, vomiting, or inability to pass gas is a clinical problem — call your clinician, do not just add more fiber.
Across published food-record studies, fiber intake is often only roughly 7–15 g/day (for example ~14.5 g in one Frontiers sample, ~7 g in another multi-hundred-person sample) against a 25–30 g target. Closing that gap is the goal; the ramp is the method.

Alcohol and eating out

Alcohol

There are no retatrutide-specific alcohol trials. Class research on GLP-1 receptor agonists suggests reduced interest in drinking for some people, and possible liver-related benefits — but that is not a green light to drink through nausea or empty calories.

Practical rules people use:

  • Skip alcohol on shot day and the day after if GI is rough
  • One drink hits harder when you have barely eaten — food first if you drink at all
  • Sulfur burps and reflux can get uglier with booze + slow emptying
  • Full evidence context: retatrutide and alcohol

Eating out

  • Scan the menu for a protein anchor first (fish, chicken, eggs, tofu), then decide sides
  • Ask for sauces on the side; heavy cream and fried appetizers can be hard to tolerate after an injection
  • Share a plate or take part of the meal home if a full portion feels too large
  • An appetizer and side dish can make a smaller meal; include a protein source
  • Soft textures (poached, steamed, grilled) beat breaded and fried when the gut is slow

If you're not eating enough

Safety

Eating too little during rapid weight loss can affect muscle, hair, hormones, and energy. Getting enough nutrition remains important when appetite is suppressed.

Research on GLP-1 and dual-agonist users found average intakes around 750 calories/day and about 33 g protein/day in one multi-hundred-person sample — far below what preserves lean mass. Reta’s stronger appetite effect makes that risk more, not less, relevant.

  • Talk to your prescriber if you are under roughly 1,200 calories (women) or 1,800 calories (men) most days — the joint advisory's micronutrient-risk thresholds — and cannot climb out of it
  • Flag dizziness, fainting, hair shedding, severe fatigue, or feeling cold all the time
  • If food restriction has a history for you (past or present eating disorder), get clinical support before pushing titration
  • Holding or slowing a phase is a valid medical conversation — not failure

A reasonable practical floor for many adults is in the 1,200–1,500 calorie range with protein protected first — men typically need the upper end or above. Individual needs vary. This is general education, not a prescription.

Eating by dose phase

See the dosage guide for titration schedules. The food guidance below covers three treatment phases:

Weeks 1–3

Appetite drop is usually milder. Use this window to learn which high-protein meals you tolerate, stock the grocery list above, and practice protein-first without pressure.

Escalation

Appetite may decrease further and nausea may increase after each dose increase. Try smaller, more frequent meals, shakes, and soft foods on injection day. If you cannot eat, tell your prescriber before the next increase.

Maintenance

Gastrointestinal symptoms often settle while appetite stays low. Focus on adequate protein, gradually increasing fiber, and getting enough vitamins and minerals during treatment.

What the research shows

Operational guidance above is grounded in published GLP-1-class nutrition research and retatrutide pharmacology. There is still no published food-intake study in retatrutide trial participants; class data plus mechanism is the evidence base.

The nutrition problem on GLP-1 drugs

Two recent studies document how poorly people eat — not by choice, but because appetite suppression works.

Study 1 — nutrient intake (Frontiers in Nutrition, April 2025): 69 adults on a GLP-1 receptor agonist for at least one month completed 3-day food records. Intake fell short of Dietary Reference Intakes across multiple nutrients:

Swipe sideways to see every column.

NutrientActual IntakeRecommendedStatus
Fiber14.5g25-30gDeficient
Calcium863mg1,000-1,200mgDeficient
Iron12.1mg18mg (women)Deficient
Magnesium266mg310-420mgDeficient
Potassium2,186mg2,600-3,400mgDeficient
Vitamin A560 mcg RAE700-900 mcg RAEDeficient
Vitamin C51mg75-90mgDeficient
Vitamin D4 mcg15 mcgDeficient
Vitamin E9.6mg15mgDeficient
Choline305mg425-550mgDeficient

Participants also overconsumed fat as a share of calories. Protein looked “fine” as a percentage of calories but was low on a grams-per-kilogram basis — the measure that matters for muscle during weight loss. Authors concluded patient-centered nutrition guidance is essential.

Study 2 — calories and protein (Stachowska et al., 48-hour diaries in 387 adults on GLP-1 or dual GIP/GLP-1 agonists; preprint 2025, later peer-reviewed): mean intake was 753 calories/day and 33.4 g protein/day; fewer than 10% met recommended protein. Higher total protein predicted more weight-loss success (beta = 0.446, p = 0.014) — people who ate more protein lost more weight, not less.

Why reta may amplify the problem

Those studies covered one- and two-receptor drugs. Retatrutide is a triple agonist (GLP-1, GIP, glucagon). Stronger combined appetite suppression means the under-eating pattern seen on semaglutide and tirzepatide is a floor of concern, not a ceiling. Inferences here are mechanistic; dietary intake inside retatrutide trials has not been published.

The glucagon factor (carbs are not the enemy)

Retatrutide is the advanced candidate that also activates the glucagon receptor. Glucagon mobilizes hepatic glycogen and supports gluconeogenesis. Chronic receptor agonism on top of a very low-carbohydrate or zero-carb pattern could, in theory, worsen glycogen depletion — fatigue, brain fog, poor training quality.
That does not mean high-carb dieting. It means extreme carb restriction popular in some weight-loss communities may be a worse fit on reta than on GLP-1-only drugs. A moderate carb range from whole foods (often discussed around 100–150 g/day — oats, fruit, potato, rice, legumes) is a reasonable default until trials test diet compositions. This is pharmacology inference, not a head-to-head diet RCT.

Glucagon activity also raises energy expenditure (thermogenesis, hepatic fat oxidation). Burning more at rest while eating 750–1,000 calories is how deficits become extreme and lean mass takes the hit.

Protein targets in the literature

An Obesity Pillars narrative review (August 2025) on nutrition with GLP-1 therapies stresses adequate macros, micros, fluid, higher protein, and resistance training for muscle preservation. Practical ranges used clinically:
PopulationTargetExample (80kg person)
General adults0.8 g/kg/day64g
Adults on weight loss therapy1.2-1.6 g/kg/day96-128g
Significant weight loss + training1.6-2.0 g/kg/day128-160g

The 2025 joint advisory’s lean-mass-based target (1.5 g/kg lean mass, or 80–120 g/day absolute) is the cleaner GLP-1-class reference when body composition is known.

Micronutrient gaps to watch

When intake drops under roughly 1,200 kcal/day for women or 1,800 kcal/day for men (the joint advisory's micronutrient-risk thresholds), food alone often cannot close gaps. Discuss labs and supplements with a clinician; common conversation starters from the Frontiers pattern:
NutrientWhy it mattersCommon form
Vitamin DLow in many GLP-1 users; bone support during rapid weight lossVitamin D3 as directed
MagnesiumMuscle function, sleep, energy; often under targetMagnesium glycinate
CalciumBone density concern with rapid lossCalcium citrate
IronFatigue and anemia risk, especially in womenAs directed after labs
FiberMotility on a slowed gut; ramp, do not dumpPsyllium, start low

A multivitamin is baseline insurance; large documented gaps may need targeted repletion.

What adequate looks like (sample day)

Not a prescription — an illustration of protein-first totals when appetite allows more than shakes:

Swipe sideways to see every column.

MealExampleProteinApprox. calories
BreakfastGreek yogurt with berries and a little granola~22g~280
LunchChicken, quinoa, roasted vegetables~35g~420
AfternoonCottage cheese or a protein shake~24g~200
DinnerSalmon, sweet potato, steamed broccoli~30g~450
Rough daily total: ~111 g protein, ~1,350 calories. At higher appetite suppression these portions will feel large — eat protein first; use liquids when solids fail. For muscle-preservation context see muscle loss on retatrutide; for GI rates see side effects.

Frequently Asked Questions

What should I eat when taking retatrutide?

Protein first (Greek yogurt, eggs, fish, chicken, cottage cheese, whey), then soft complex carbs (oats, fruit, potato, rice), then cooked vegetables. Aim for the joint-advisory protein frame — about 80–120 g/day if you do not know lean mass, or ~1.5 g per kg lean mass. On shot day, stay soft and small. Avoid large fried meals, heavy spice, and raw fiber piles when the gut is slow.

How much protein should I eat per day on retatrutide?

The 2025 joint advisory (ACLM, ASN, OMA, TOS) targets 1.5 g protein per kg lean body mass per day, or 80–120 g/day for most adults when lean mass is unknown. During active weight loss it cites about 1.2–1.6 g/kg body weight (adjusted body weight at higher BMIs). Stay above a rough floor of 0.4–0.5 g/kg/day. Pair protein with resistance training at least three times weekly. None of this is retatrutide-specific trial diet guidance; it is GLP-1-class consensus applied to a stronger appetite-suppressing drug.

How many calories should I eat on retatrutide?

There is no retatrutide-specific calorie prescription. Class research found many people eating around 753 calories/day — dangerously low for most adults. Living under roughly 1,000–1,200 calories for long stretches raises risk of muscle loss, nutrient gaps, hair thinning, fatigue, and metabolic slowdown. The joint advisory flags micronutrient risk especially below about 1,200 kcal/day for women and 1,800 for men. A practical floor for many adults is 1,200–1,500 calories with protein protected — men typically need the upper end or above; individual needs vary. Get personalized guidance from a clinician or RD.

Should I eat differently on injection day?

No clinical trial has fixed meal timing around retatrutide injections. Users commonly report the hardest 24–48 hours after the pin. Soft, low-fat, smaller meals and protein shakes are the usual plan; some people front-load a better protein meal the day before. Individual response varies.

Can I do keto on retatrutide?

Very low-carb diets may be a poorer fit on reta than on GLP-1-only drugs because reta also activates the glucagon receptor, which promotes glycogen breakdown. On keto, glycogen is already low. Adding pharmacological glucagon activity could theoretically worsen fatigue, dizziness, and training quality. Moderate carbohydrate from whole foods is the more cautious default. No RCT has tested keto versus moderate carb on retatrutide — this is mechanism, not a diet trial result.

Can I do a carnivore (zero-carb) diet on retatrutide?

Carnivore is likely the least suitable pattern for reta specifically: zero carb on top of glucagon-driven glycogen use, no fiber (constipation risk on an already slowed gut), and missing plant micronutrients in a population already shown to run deficient. High protein is the one strength — and you can get that without zero-carb extremes. No clinical study has tested carnivore on retatrutide.

Why am I so tired on retatrutide?

Common dietary causes: not enough total calories, very low carbohydrate intake with glucagon activity in the mix, dehydration from GI symptoms, and micronutrient gaps (iron, vitamin D, magnesium). Rule out non-diet causes with your clinician if fatigue is severe or sudden.

Do I need to take supplements on retatrutide?

Possibly. Food-record studies in GLP-1 users show widespread shortfalls in vitamin D, calcium, iron, magnesium, potassium, and others. When intake drops hard, diet alone rarely covers needs. A multivitamin is baseline; targeted repletion should follow intake review and labs — not internet megadosing.

Does eating more protein help with weight loss on retatrutide?

Class data says higher protein predicts better weight-loss success and supports a better fat-to-lean loss ratio. Protein preserves metabolically active tissue during a deficit. On reta, protein is less about “boosting burn” and more about not cannibalizing muscle while appetite is pharmacologically low.

What is the fiber paradox on GLP-1 drugs?

You need more fiber than most people on these drugs are eating, but dumping a large fiber load (huge salad, full psyllium dose) into a slowed gut often worsens bloating and constipation. Ramp fiber, pair with water, prefer cooked sources first, and treat severe constipation as a clinical issue — not a cue to double the powder.

Sources

  • Johnson, B., et al. (2025). Investigating nutrient intake during use of glucagon-like peptide-1 receptor agonist: a cross-sectional study. Frontiers in Nutrition, 12. DOI: 10.3389/fnut.2025.1566498
  • Stachowska, E., et al. (2025/2026). Dietary intake patterns and nutritional adequacy among adults with overweight or obesity treated with GLP-1 or dual GIP/GLP-1 receptor agonists. Journal of Translational Medicine (peer-reviewed; earlier preprint DOI: 10.21203/rs.3.rs-7640335/v1). Published version
  • Mietlicki-Baase, E.G., et al. (2017). Daily supplementation of dietary protein improves the metabolic effects of GLP-1-based pharmacotherapy in lean and obese rats. Physiology & Behavior, 177, 122-128. DOI: 10.1016/j.physbeh.2017.04.017
  • Fitch, A., et al. (2025). Application of nutrition interventions with GLP-1 based therapies: A narrative review of the challenges and solutions. Obesity Pillars, 16, 100205. DOI: 10.1016/j.obpill.2025.100205
  • American College of Lifestyle Medicine, American Society for Nutrition, Obesity Medicine Association, and The Obesity Society. (2025). Nutritional priorities to support GLP-1 therapy for obesity: A joint advisory. Obesity Pillars. (Protein target of 1.5 g/kg lean body mass/day or 80-120 g/day; resistance training at least 3×/week plus 150 min aerobic weekly to preserve muscle.) Open access (PMC)
  • Jastreboff, A.M., et al. (2023). Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. DOI: 10.1056/NEJMoa2301972
  • Eli Lilly and Company. (2025). Lilly's retatrutide achieved significant weight loss and pain relief in adults with obesity and knee osteoarthritis. Press release.
  • Healthline. (2025). The Carnivore Diet: A Beginner's Guide. (Carnivore diet aims for zero carbohydrates, contains no fiber, and may lack vitamin C, folate, and other plant-derived micronutrients.) Article.
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.
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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.

Grounded in primary sources
NEJMThe LancetJAMAFDAClinicalTrials.gov

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