Question 1

What is a calorie deficit?

Accepted Answer

A calorie deficit occurs when you consume fewer calories than your body burns. Since body fat stores approximately 7,700 kcal per kg (3,500 kcal per pound), a deficit of 500 kcal/day theoretically produces about 0.5 kg (1 lb) of fat loss per week. In practice, the body adapts over time, so results vary. A deficit is required for weight loss; a surplus is required for weight gain (muscle building).

Question 2

What is TDEE?

Accepted Answer

TDEE stands for Total Daily Energy Expenditure — the total number of calories your body burns in a day, including Basal Metabolic Rate (BMR, calories burned at rest), physical activity, and the thermic effect of food. TDEE depends on age, sex, weight, height, and activity level. This calculator estimates TDEE as: body weight (kg) × 22 × activity multiplier (a simplified approach).

Question 3

How large should my daily calorie deficit be?

Accepted Answer

Most nutritionists recommend a deficit of 250-500 kcal/day for sustainable weight loss of 0.25-0.5 kg per week. A deficit larger than 1,000 kcal/day is generally considered too aggressive — it can cause muscle loss, nutrient deficiencies, metabolic adaptation, and rebound weight gain. Very low calorie diets (VLCDs) below 800 kcal/day should only be followed under medical supervision.

Question 4

Why does weight loss slow down over time?

Accepted Answer

As you lose weight, your body weight decreases, so your BMR and TDEE decrease too — you need fewer calories to maintain a lower body weight. Additionally, metabolic adaptation (adaptive thermogenesis) causes the body to become more efficient over time. What was a 500 kcal deficit at the start may become only a 200 kcal deficit after 3 months of dieting, requiring adjustments.

Question 5

What is the difference between fat loss and weight loss?

Accepted Answer

Weight loss includes loss of fat, water, glycogen stores, and potentially muscle. Fat loss specifically targets adipose tissue. Rapid weight loss (>1 kg/week) often includes significant muscle loss, which is counterproductive. To preserve muscle during a deficit, ensure adequate protein intake (1.6-2.2g/kg body weight), perform resistance training, and keep your deficit modest (250-500 kcal/day).

Calorie Deficit Calculator

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