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How to Calculate Your Calorie Deficit to Lose Weight
A healthy calorie deficit is 300 to 750 calories below your Total Daily Energy Expenditure (TDEE). To calculate yours: use the Mifflin-St Jeor formula to find your Basal Metabolic Rate, multiply by your activity level to get your TDEE, then subtract 300 to 750. This produces 0.5 to 1.5 pounds of fat loss per week without triggering muscle loss or metabolic slowdown.
You have probably been told that weight loss comes down to eating less and moving more. That is directionally true, but it leaves out everything that actually determines whether your approach works. The specific number that matters is your calorie deficit — how large it is, how it is calculated for your body, and how to sustain it without losing muscle in the process.
Understanding Your TDEE
Your Total Daily Energy Expenditure is the total number of calories your body burns in a day, covering basic organ function, exercise, and daily movement. It has four components:
- Basal Metabolic Rate (BMR): The energy your body uses at complete rest. This accounts for 60 to 70 percent of total calorie burn and is primarily determined by lean muscle mass.
- Thermic Effect of Food: The energy cost of digesting food — approximately 10 percent of total burn. Protein has the highest thermic effect of any macronutrient.
- Exercise Activity Thermogenesis: Calories burned during intentional workouts.
- Non-Exercise Activity Thermogenesis (NEAT): Everything else — walking, standing, fidgeting. This varies by 200 to 900 calories per day between individuals.
The Mifflin-St Jeor Formula: The Clinical Standard
For women: BMR = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161
For men: BMR = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5
Once you have your BMR, multiply by your activity level:
| Activity Level | Description | Multiplier |
| Sedentary | Desk job, minimal movement | BMR x 1.2 |
| Lightly active | Exercise 1 to 3 days per week | BMR x 1.375 |
| Moderately active | Exercise 3 to 5 days per week | BMR x 1.55 |
| Very active | Hard exercise 6 to 7 days per week | BMR x 1.725 |
| Athlete level | Physically demanding job or twice-daily training | BMR x 1.9 |
What Is a Healthy Calorie Deficit?
The clinical sweet spot for sustainable fat loss is a deficit of 300 to 750 calories below your TDEE. This range is endorsed by the Academy of Nutrition and Dietetics, the American Heart Association, and most obesity medicine guidelines. It produces 0.5 to 1.5 pounds of weight loss per week without triggering the muscle loss and metabolic adaptation that larger deficits cause. For approximately one pound of fat loss per week, a 500-calorie daily deficit is the standard calculation.
When Diet and Exercise Alone Are Not Moving the Needle
If you have been following a structured calorie deficit for eight or more weeks and seeing less than half a pound of weekly loss, it is a reasonable time to explore whether medical support changes your trajectory. GLP-1 medications at AHC reduce the neurological drive to eat, making the deficit that currently requires constant effort genuinely manageable.
Frequently Asked Questions
1. How do I calculate my calorie deficit to lose 1 pound per week?
Calculate your TDEE using the Mifflin-St Jeor formula and subtract 500 calories. That is your daily intake target for roughly one pound of fat loss per week.
2. What is a healthy calorie deficit for weight loss?
A deficit of 300 to 750 calories below your TDEE. Deficits above 1,000 calories per day consistently produce muscle loss, nutrient deficiencies, and long-term metabolic slowdown.
3. Will I lose muscle on a calorie deficit?
Not if you protect against it. Eat 1.2 to 1.6 grams of protein per kilogram of body weight daily and perform resistance training at least three times per week. Keep your deficit in the 300 to 750 calorie range.
Get Personalized Numbers at AHC
AHC’s Weight Loss Calculator provides your personalized TDEE, safe daily calorie target, and projected weekly loss. If medical support is appropriate, connect with a physician at AHC.
Medical Disclaimer: Compounded semaglutide and tirzepatide are not FDA-approved and have not been evaluated for safety, efficacy, or quality by the FDA. All clinical services are provided by independently contracted, U.S.-licensed clinicians. Individual results vary. This content is for informational purposes only and does not constitute medical advice.