Question 1

How does a calorie deficit cause weight loss?

Accepted Answer

A calorie deficit means you're consuming less energy than your body expends. To make up the shortfall, your body breaks down stored energy — primarily body fat, but also some muscle mass if the deficit is too aggressive or protein intake is too low. Approximately 7,700 calories equals 1 kg of body fat, so a deficit of 550 calories per day produces roughly 0.5 kg of fat loss per week.

Question 2

How large should my calorie deficit be?

Accepted Answer

Most evidence supports a deficit of 500–750 calories below TDEE for sustainable fat loss. This produces 0.5–0.75 kg per week — a rate generally considered safe and manageable. Larger deficits (1,000+ calories below TDEE) increase the risk of muscle loss, nutritional deficiencies, metabolic adaptation, and are harder to sustain. Very low calorie diets (below BMR) should only be undertaken with medical supervision.

Question 3

Why isn't my weight loss matching the calculator's timeline?

Accepted Answer

Several factors cause real-world weight loss to differ from predictions. Water retention fluctuates daily and can mask fat loss — a consistent deficit will still produce results even if the scale doesn't move for a week. The body also adapts to prolonged deficits by reducing TDEE (metabolic adaptation), meaning you may need to adjust your target over time. Additionally, TDEE estimates are averages with ±10–15% individual variation.

Question 4

What macros should I eat on a deficit?

Accepted Answer

Protein is the most important macro during a deficit — it preserves muscle mass, is highly satiating, and has a high thermic effect (your body burns more calories digesting protein than fat or carbs). A general guideline is 1.6–2.2g of protein per kg of body weight per day. The split of remaining calories between carbs and fat is largely personal preference. The 30/40/30 split shown in this calculator is a reasonable starting point but can be adjusted.

Question 5

Should I eat back exercise calories?

Accepted Answer

It depends on how you calculated your TDEE. If you selected an accurate activity level, your exercise calories are already included in TDEE — don't eat them back. If you set your activity level to sedentary and track workouts separately, you might add back a portion of exercise calories. Most people overestimate calorie burn during exercise, so erring on the side of not eating them back is usually safer for a weight loss goal.

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