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GLP-1 Calculators

Diet on GLP-1 in 2026 — Protein, Fiber, and Calorie Floors for Reduced Appetite

Daily calorie and macronutrient targets that actually work when your appetite is down 40–60%. Built around the single finding from STEP 1 DXA substudies that matters most: protect lean mass.

Updated April 2026

Medical disclaimer: This tool is for informational purposes. Not medical advice. Consult your healthcare provider before starting, stopping, or changing any medication. Drug prices, savings cards, and coverage policies change frequently — verify current pricing directly with the manufacturer or your pharmacy.

Your inputs

Results

Daily calorie target
2,282 kcal
Maintenance: 3,032 kcal
Protein
189 g
47 g x 4 meals
Carbs
222 g
Fat
71 g
Fiber target
32 g
Water target
105 oz
Protein is non-negotiable on GLP-1. With appetite down 30–60%, most patients undershoot 60–80g/day and lose 25–40% of total weight from lean mass. Hit protein first, then fill the rest of the plate.

Why most GLP-1 diet advice is wrong for GLP-1 patients

The standard “eat less, move more” diet template assumes you’re fighting hunger. On semaglutide 2.4 mg or tirzepatide 10–15 mg, your appetite is down 40–60% and gastric emptying is slowed. The problem is the opposite: you’re not eating enough, and specifically not eating enough protein. STEP 1 and SURMOUNT-1 DXA substudies showed ~25–40% of total weight lost came from lean body mass when patients didn’t add resistance training and sufficient protein.

How to hit protein with reduced appetite

  • Whey or casein shake, twice daily: 25–30 g each. Tolerable even during titration nausea.
  • Greek yogurt / skyr / cottage cheese: 15–25 g per cup. Cold, dense, low GI burden.
  • Lean poultry and fish first: turkey breast, chicken thigh, white fish, shrimp tolerate better than fatty red meat.
  • Eggs: 6–7 g each. Two eggs + 1 scoop whey = 35 g at breakfast.
  • Front-load breakfast: appetite is least suppressed in the morning. Hit 40–50 g there.

Fat: lower than you think, for GI tolerance

Classic low-carb, high-fat template backfires on GLP-1 because fat is the slowest macronutrient to leave the stomach. Patients at 40% of calories from fat report substantially more nausea than at 25–30%. Keep fat at 25–30% of total calories, unsaturated sources (olive oil, avocado, nuts, fish). Fried food is the single most-reported nausea trigger.

Meal structure: four small beats three large

On GLP-1, four meals of 300–450 kcal often fit physiology better than two 800-kcal meals. Spacing 3–4 hours apart lets the stomach partially clear and reduces the “stuck” feeling that triggers nausea. Protein-meal skipping is the most common precursor to lean-mass loss.

A sample day on GLP-1 (1,800 kcal, 170 g protein)

  • Breakfast: 2 eggs, 1 cup egg whites, 1 scoop whey in coffee, 1 cup berries. (450 kcal, 45 g)
  • Mid-morning: 1 cup Greek yogurt, 2 tbsp chia, honey. (300 kcal, 25 g)
  • Lunch: 5 oz grilled chicken, 1 cup quinoa, vegetables, olive oil. (500 kcal, 45 g)
  • Afternoon shake: whey + water. (200 kcal, 25 g)
  • Dinner: 5 oz white fish or shrimp, roasted vegetables, small sweet potato. (350 kcal, 30 g)

What to avoid

  • Large, fatty late-evening meals: worst for GI tolerance, reflux, disturbed sleep.
  • Carbonated drinks: distend the already-slow stomach; many give them up involuntarily.
  • Sugar bombs on empty stomach: dumping-like symptoms in a minority — sweating, rapid heart rate.
  • Very low carb on top of GLP-1: some patients layer keto and develop refractory fatigue. The glucose-lowering is redundant. Moderate carb, not ketogenic.
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Frequently asked questions

Why do I feel full after 100 calories some days and fine after 800 others?

GLP-1 effect fluctuates by days since injection and individual tolerance. Most patients report peak appetite suppression 24–72 hours after the weekly dose, tapering toward day 6–7. Day 7 is often the highest-appetite day of the week. Plan higher-calorie, higher-protein meals for that window if you're struggling to hit targets.

What's the protein target that actually matters?

0.8–1.0 g per pound of goal body weight. For a 200 lb patient with a 170 lb goal, that's 140–170 g/day. Most patients on therapeutic doses are eating 50–70 g/day — roughly half of what they need. DXA data from real-world cohorts: patients below 0.7 g/lb lost 31–38% of weight as lean mass; those at 0.9 g/lb lost 15–22%. That 100–180 kcal/day RMR difference at 12 months is the margin between maintenance and regain.

Can I skip the gym if I'm losing weight fast?

No. Rapid loss without training produces the worst body composition outcomes. 2 resistance sessions per week of 30 minutes is the minimum effective dose. It doesn't have to be heavy or long — it has to be consistent. See the exercise on GLP-1 guide for a specific training template.

What about intermittent fasting on GLP-1?

Unnecessary for most patients and counterproductive for many. You're already in a large calorie deficit from appetite suppression; adding a 16-hour fast makes protein targets nearly impossible to hit. If you already do IF and it's working, fine; don't add it de novo.

Do I need a multivitamin?

Reasonable insurance on a reduced-intake diet. Iron, B12, vitamin D, and magnesium are the most commonly deficient micronutrients in weight-loss cohorts. A basic daily multi + separate 2000 IU vitamin D and 200–400 mg magnesium is a conservative template.

Will my taste change?

Often, yes. Many patients report aversion to red meat, fatty foods, and sweet desserts — the same categories most weight-gain-promoting, so it's mostly a feature not a bug. Aversions usually stabilize after 2–3 months.

How much fiber do I actually need?

Target 25–35 g/day. GLP-1 slows gastric emptying, predisposing you to constipation (STEP 1 showed 22% of semaglutide patients vs 10% placebo). Psyllium husk 5 g/tbsp pre-bedtime, chia seeds 10 g/2 tbsp, lentils 12–15 g/cooked cup, berries and avocado. Add gradually over 2–3 weeks to let the gut adapt.

Is the calorie floor important?

Yes — aggressive undereating produces worse outcomes than modest deficit. Don't go below 1,200 (women) or 1,500 (men) kcal/day without medical supervision. STEP 1 and SURMOUNT-1 used a 500 kcal/day structured deficit; real-world patients often drift to 1,200 from appetite suppression alone, which accelerates lean mass loss.

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