Mounjaro Calorie Calculator
Calculate your maintenance calories and a safe deficit range to support steady weight loss alongside Mounjaro treatment.
Understanding how many calories your body needs is an important part of planning weight loss — especially alongside medication like Mounjaro. This calculator estimates your maintenance calories (how much you need to stay the same weight) and suggests a deficit range for gradual loss.
GLP-1 medications reduce appetite, which naturally lowers calorie intake. This tool helps you understand the numbers behind that change.
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What this calculator does
This calculator uses the Mifflin-St Jeor equation to estimate your basal metabolic rate (BMR), then multiplies it by an activity factor to find your maintenance calories. It then applies your chosen deficit percentage to suggest a calorie target for weight loss.
Who it is for
Adults using or considering Mounjaro who want to understand their calorie needs during treatment. Also useful for anyone wanting a science-based estimate of their daily calorie requirements.
How to use it
Enter your weight, height, age, sex, and activity level. Choose a weight-loss pace (slower, moderate, or faster deficit). Click 'See My Result' to see your maintenance calories, target intake, and estimated weekly loss.
How the calculation works
BMR is calculated using the Mifflin-St Jeor equation. Maintenance calories = BMR × activity multiplier. The deficit is applied as a percentage: slower ≈ 15%, moderate ≈ 20%, faster ≈ 30%. We enforce a minimum safe intake floor (1,200 kcal for women, 1,500 kcal for men).
Worked example
Female, 40 years old, 85 kg, 165 cm, lightly active: BMR ≈ 1,508 kcal. Maintenance ≈ 2,074 kcal. Moderate deficit (20%) = target ≈ 1,659 kcal/day. Daily deficit ≈ 415 kcal, estimated weekly loss ≈ 0.38 kg.
Assumptions and limitations
- Uses the Mifflin-St Jeor equation, which is widely considered the most accurate for estimating BMR
- Activity multipliers are estimates — real energy expenditure varies
- Calorie deficit calculations assume a simplified model (7,700 kcal per kg of body weight)
- Does not account for metabolic adaptation, hormonal changes, or medication effects on metabolism
- Minimum safe intakes are general guidelines — discuss lower targets with a clinician
Frequently asked questions
How many calories should you eat on Mounjaro?
There is no single answer. Most people on Mounjaro naturally eat less due to reduced appetite. A moderate deficit of 15–25% below maintenance is generally considered sustainable. Your prescriber or a dietitian can help set a personalised target.
Should you count calories on Mounjaro?
Calorie counting is not required, and many people lose weight on Mounjaro without tracking. However, understanding your approximate calorie needs can help you make informed food choices and ensure adequate nutrition.
What is BMR?
Basal Metabolic Rate is the number of calories your body burns at complete rest — just to keep your organs functioning. It accounts for about 60–75% of your total daily energy expenditure.
Related calculators
- BMI Calculator for Mounjaro — Find your BMI, see which category it falls into, and understand how it relates to eligibility criteria for treatments like Mounjaro.
- Mounjaro Calorie Deficit Calculator — Enter your maintenance calories and a target intake (or desired weekly loss) to see the size of your deficit and projected weight change ove
- Mounjaro Protein Calculator — Find out how much protein you should aim for each day and per meal to support muscle preservation during weight loss on GLP-1 medication.
- Mounjaro vs Wegovy Calculator — Enter your weight and the monthly costs of each medication to compare projected weight loss, total spend, and cost per kilogram lost over yo
- Mounjaro Weight Loss Calculator — This planning tool projects how much weight you could lose over a chosen number of weeks, using conservative, moderate, or ambitious assumpt
Related guides
- How Many Calories Should You Eat on Mounjaro? — Understanding your calorie needs during Mounjaro treatment — maintenance, deficit, and safe intake ranges explained.
- Mounjaro vs Wegovy for Weight Loss — A balanced comparison of Mounjaro (tirzepatide) and Wegovy (semaglutide) — mechanism, effectiveness, cost, and side effects.
- How Much Weight Can You Lose on Mounjaro? — A realistic look at expected weight loss on Mounjaro (tirzepatide), based on clinical trial data and practical planning advice.
- How Much Protein Should You Eat on Mounjaro? — Why protein matters during GLP-1 weight loss and how to hit your daily target with practical meal guidance.
- What BMI Means for Weight-Loss Injections — How BMI is used to assess eligibility for weight-loss medications like Mounjaro and Wegovy, and its limitations.
Sources and references
Mifflin-St Jeor equation (Mifflin et al., AJCN 1990), NICE guidance on calorie intake, NHS weight loss guidelines
Last updated
Last reviewed: 2025-04-12.