How many calories should I eat to lose weight?
For most adults, a deficit of 500–750 calories per day below maintenance produces about 1–1.5 lb per week of fat loss while preserving most lean mass. Avoid going below your BMR (the calculator's first result) for extended periods, and as a general floor avoid sustained intake under roughly 1,200 cal/day for women or 1,500 cal/day for men without medical supervision.
Is this calculator for both men and women?
Yes. The Mifflin-St Jeor equation uses a different constant for each sex (+5 for men, -161 for women) to reflect average differences in lean mass and body composition. Selecting Male or Female on the gender toggle switches the formula automatically.
Why is my real-world intake different from what the calculator says?
Three usual reasons. First, BMR formulas carry roughly ±10% individual error from genetics and body composition. Second, food labels and home portions are typically underestimated by 20–50%. Third, activity multipliers assume average movement at that level — your actual NEAT (fidgeting, walking, posture) can swing TDEE by hundreds of calories. Track for 2–3 weeks and adjust against the trend.
What is TDEE and how is it different from BMR?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest just to keep organs running — typically 60–70% of total daily burn. TDEE (Total Daily Energy Expenditure) adds the calories from movement, exercise, and digesting food. The calculator reports TDEE as Maintenance Calories — that's the budget that keeps weight stable.
Should I cut calories more aggressively to speed up results?
Usually not. Deficits beyond about 1,000 cal/day or below 1,200–1,500 cal/day total tend to drive muscle loss, fatigue, hormonal disruption, and rebound eating. The CDC and NIH both recommend a gradual loss rate of 1–2 lb per week, which a 500–1,000-calorie daily deficit comfortably produces. Very low calorie diets should be supervised by a clinician.
Are 'calories in / calories out' really all that matters?
For weight change, energy balance is the primary driver — you can technically lose weight on any food source as long as you're in a deficit. But food quality drives hunger, performance, sleep, micronutrient status, and long-term adherence. Two diets with identical calories can feel very different. Hit your calorie target with mostly whole, protein-rich, fibrous foods and the rest of the plan gets easier.
How accurate is this calculator?
Mifflin-St Jeor predicts measured BMR within 10% for roughly 80% of healthy adults. The TDEE multipliers add a second layer of estimation. Treat the result as a starting point with a ±10–15% margin, then refine with 2–3 weeks of weight-trend data — the scale's response is more accurate than any formula.
How do I split my calories into protein, carbs, and fat?
Use 4 calories per gram of protein and carbohydrate and 9 calories per gram of fat. A practical starting split during fat loss is 0.7–1.0 g protein per pound of body weight, 0.3–0.4 g fat per pound, and the remaining calories from carbohydrates. Adjust based on training style, satiety, and how you feel after 2–3 weeks.
Why do my calorie needs seem to drop as I lose weight?
Two reasons. A lighter body needs less energy to move and maintain, so BMR drops by roughly 7 cal per pound lost. On top of that, the body adapts during sustained dieting by reducing non-exercise activity and slightly downshifting thyroid output (adaptive thermogenesis). Recalculate every 10–15 lb and add a refeed week or maintenance phase periodically.
Does this work for older adults?
Yes. Age is in the formula (-5 calories per year), so a 60-year-old will get a lower BMR than a 30-year-old at the same weight and height. Just be careful with the activity multiplier — choose based on actual movement, not what you used to do — and consider that older adults often benefit from a slightly higher protein intake (around 1.0–1.2 g per kg) to protect against sarcopenia.
Can I use this during pregnancy or breastfeeding?
Not directly. Pregnancy and lactation add 300–500 cal/day in needs and have specific nutrient requirements that this calculator doesn't model. Use the ACOG and CDC guidance and work with a prenatal provider or registered dietitian for an individualized target.
Should I eat back the calories my fitness tracker says I burned?
Mostly no. Wrist-based and most chest-strap estimates of exercise calories are inflated by 20–90% depending on activity and intensity. If you're using a TDEE multiplier that already accounts for your training (Moderate or Active), don't double-count by eating back tracker calories. If you do choose to eat some back, cap it at 50% of the displayed number.
