TDEE Calculator for GLP-1 Users
How Many Calories Do You Need on Ozempic or Wegovy?
GLP-1 medications dramatically reduce appetite — but eating too little can cause muscle loss and metabolic slowdown. Know your TDEE to find the right deficit and protect your long-term results.
What Is TDEE?
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day. It is calculated by multiplying your Basal Metabolic Rate (BMR) — the calories needed just to stay alive — by an activity multiplier.
Your BMR accounts for breathing, circulation, hormone production, and cell repair. Activity adds on top: walking, exercise, even fidgeting. TDEE is the number of calories at which your weight stays constant (maintenance).
To lose weight: eat below TDEE. To preserve muscle on GLP-1 medications: stay within a moderate deficit of 500–750 calories per day below your TDEE — not 1,500.
Why TDEE Is Critical on GLP-1 Medications
The Hidden Danger of Appetite Suppression
Semaglutide and tirzepatide can reduce appetite so effectively that many users eat only 600–900 calories per day without realizing it. While this creates rapid initial weight loss, extreme deficits signal the body to break down muscle for fuel — permanently lowering your resting metabolic rate.
Studies show that without adequate protein and a moderate (not extreme) calorie deficit, GLP-1 users can lose 25–40% of total weight loss as lean muscle mass rather than fat. Knowing your TDEE puts you in control.
Metabolic Adaptation During Weight Loss
As you lose weight on a GLP-1, your TDEE decreases — a smaller body burns fewer calories. Additionally, rapid weight loss triggers metabolic adaptation: your body becomes more efficient, burning fewer calories than predicted by standard formulas.
Recalculate your TDEE every 10–15 lbs lost and adjust your calorie targets accordingly. Shotlee lets you log your food intake alongside injections so you can spot when intake drifts too far below your estimated TDEE.
Harris-Benedict Formula
The most widely used formula for estimating BMR. TDEE = BMR × Activity Multiplier.
BMR Formula — Men
Example: A 35-year-old man, 200 lbs (90.7 kg), 5'10" (177.8 cm): BMR ≈ 88.36 + 1215 + 854 − 199.5 = 1,958 cal/day
BMR Formula — Women
Example: A 40-year-old woman, 180 lbs (81.6 kg), 5'5" (165 cm): BMR ≈ 447.6 + 755 + 512 − 173 = 1,542 cal/day
Activity Multipliers
TDEE Reference Table
Estimated daily calorie needs by body weight and activity level (assumes average adult height and age 35–45).
Protein Needs and Safe Deficit on GLP-1
Recommended Daily Protein
Protein is the primary nutrient for preserving muscle during calorie restriction. On GLP-1 medications, aim for 0.7–1.0 grams of protein per pound of body weight daily — the upper end if you are actively doing resistance training.
Safe Calorie Deficit for GLP-1 Users
GLP-1 medications are powerful enough that you do not need an aggressive calorie deficit to lose weight. Research and clinical experience suggest a 500–750 calorie/day deficit below your TDEE strikes the best balance between fat loss and muscle preservation.
Frequently Asked Questions
How many calories should I eat on Ozempic?
There is no one-size-fits-all answer — it depends on your TDEE. Calculate your TDEE using the Harris-Benedict formula and subtract 500–750 calories per day. Most people on Ozempic at maintenance weight are between 1,500 and 2,400 calories per day before accounting for deficit. Eating fewer than 1,200 calories per day (women) or 1,500 (men) is generally not recommended without medical supervision.
Does Ozempic slow your metabolism?
Not directly — but rapid weight loss from any cause, including Ozempic, causes metabolic adaptation (your resting metabolic rate decreases as you get lighter). Eating adequate protein (0.7–1g per lb of body weight) and doing resistance training are the best strategies to minimize this effect and preserve metabolically active muscle tissue.
How do I track calories alongside my GLP-1 injections?
Shotlee lets you log your injection doses alongside daily health metrics. Pair it with a calorie-tracking app like MyFitnessPal or Cronometer for food logging. Reviewing both together helps you spot patterns — for example, nausea side effects reducing intake more than intended in the days after your injection.