Calorie Deficit FAQ

Common questions about calorie deficits, TDEE, macros, and safe weight loss.

What is a calorie deficit?

A calorie deficit means consuming fewer calories than your body burns. When you eat less than your Total Daily Energy Expenditure (TDEE), your body uses stored energy (primarily fat) to make up the difference. A consistent deficit over time leads to weight loss.

How big should my calorie deficit be?

Most experts recommend a deficit of 250-750 calories per day for sustainable weight loss. A 500-calorie daily deficit yields about 1 pound of weight loss per week. Larger deficits can lead to faster results but may cause muscle loss, fatigue, and nutritional deficiencies. Never drop below 1,200 calories (women) or 1,500 calories (men) without medical supervision.

What is TDEE?

Total Daily Energy Expenditure (TDEE) is the total calories your body burns in a day. It includes your Basal Metabolic Rate (BMR) — calories burned at rest — plus calories from physical activity and the thermic effect of food (energy used digesting meals). TDEE varies based on age, sex, weight, height, and activity level.

What is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is the most widely recommended formula for estimating BMR. Published in 1990, it's considered more accurate than older equations like Harris-Benedict. For men: 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5. For women: 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161.

How important is protein during a calorie deficit?

Protein is critical during a deficit. It preserves muscle mass, increases satiety (helping you feel full longer), and has a higher thermic effect than fats or carbs. Most research supports 0.7-1.0 grams of protein per pound of body weight during a deficit. Higher protein intake becomes even more important as you get leaner.

What is metabolic adaptation?

Metabolic adaptation (sometimes called "metabolic slowdown") occurs when your body adjusts to a prolonged calorie deficit by reducing energy expenditure. Your BMR decreases as you lose weight, and hormonal changes can further reduce calorie burning. This is why weight loss often slows over time and why recalculating your targets every 10-15 pounds is important.

Should I eat back exercise calories?

It depends on how you set your activity level. If your TDEE already accounts for exercise via the activity multiplier, eating back additional exercise calories would reduce your effective deficit. If you set your activity as "sedentary" and exercise separately, eating back some (not all) exercise calories is reasonable. Exercise calorie estimates from trackers are often inflated by 20-40%.

Is it safe to lose more than 2 pounds per week?

For most people, losing more than 2 pounds per week is not recommended unless under medical supervision. Rapid weight loss increases risk of muscle loss, gallstones, nutritional deficiencies, and metabolic disruption. The exception is very overweight individuals who may safely lose faster in the initial weeks due to water weight and higher fat reserves.

Why does the calculator have a 1,200 calorie minimum?

Below 1,200 calories, it becomes difficult to meet basic nutritional needs for vitamins, minerals, and macronutrients. Very low calorie diets (VLCDs) below this threshold should only be followed under medical supervision with proper monitoring and supplementation.