GLP-1 Calorie Calculator | How Much to Eat on Semaglutide & Tirzepatide | Ondra Health
GLP-1 Calorie Calculator

How much should you eat
on semaglutide or tirzepatide?

Standard calorie calculators tell you to eat less. GLP-1 already does that. The real question is how little is too little — and where your safe minimum is.

The pivotal clinical trials for semaglutide (STEP-1) and tirzepatide (SURMOUNT-1) both used a 500 calorie daily deficit as the dietary protocol alongside medication.

Your Details

Calculate your calorie targets

Uses the Mifflin-St Jeor equation — the most widely validated method for estimating resting calorie needs — then adjusts for activity and goal.

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Your goal

Your GLP-1 Calorie Targets
GLP-1 patients can eat dangerously little without realizing it. When appetite suppression is strong, some patients consistently eat below 800 calories. Sustained restriction at that level causes muscle loss, hair thinning, fatigue, and nutrient deficiencies — and can slow your metabolism long-term.
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Why "just eat less" is the wrong approach on GLP-1

The medication handles appetite suppression. Your job is to eat the right amount — not as little as possible.

500 cal deficit is the clinical standard
Both the STEP-1 (semaglutide) and SURMOUNT-1 (tirzepatide) pivotal trials used a structured 500 calorie daily deficit alongside medication — not a very low calorie diet. The medication amplifies the effect of a moderate deficit.
Too low triggers muscle loss
When calorie intake drops too far, the body draws on muscle tissue for energy alongside fat. This lowers your resting metabolic rate — making it harder to maintain your results after stopping treatment.
Your calorie floor is non-negotiable
The floor shown here reflects your estimated BMR — the minimum calories your body needs for basic organ function. Eating consistently below BMR while on a medication that suppresses hunger is not safe, regardless of weight loss goals.
A moderate deficit works
A 500 cal/day deficit produces approximately 1 lb of fat loss per week under normal conditions. GLP-1 medications sustain this deficit effortlessly for most patients — pushing further offers little additional benefit and increases risk.
Disclaimer: This calculator uses the Mifflin-St Jeor equation to estimate Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE). Results are estimates — individual needs vary based on body composition, health status, and medication response. This is not medical advice. Consult your licensed healthcare provider before changing your diet. People with kidney disease, heart conditions, eating disorder history, or other medical needs should follow provider-specific guidance. References: Mifflin et al. (1990), American Journal of Clinical Nutrition. Wilding et al. (2021), NEJM — STEP-1. Jastreboff et al. (2022), NEJM — SURMOUNT-1.