📅 Last reviewed: July 2026 · MySleepTool Editorial Team
Calorie Calculator (TDEE)
Find your Total Daily Energy Expenditure — how many calories you burn per day — and your calorie targets for weight loss, maintenance, or gain.
Biological sex
Maintenance (TDEE)
—
calories/day to maintain weight
BMR (at rest)
—
calories burned doing nothing
Mild weight loss
—
−250 cal/day · ~0.25kg/week
Weight loss
—
−500 cal/day · ~0.5kg/week
Weight gain
—
+300 cal/day · gradual gain
Muscle building
—
+500 cal/day with training
💤 Sleep & calorie intake: Poor sleep increases ghrelin (hunger) and decreases leptin (satiety) — adding ~300–500 extra calories per day without you realizing. Improving sleep to 7–9 hours is one of the most effective weight management tools. Use our Sleep Cycle Calculator to optimize your sleep timing.
Calories, Metabolism, and Sleep — The Hidden Connection
Calorie intake and sleep quality are more deeply connected than most nutrition guides acknowledge. Chronic sleep restriction produces hormonal changes that systematically increase caloric intake — making it one of the most significant and underappreciated drivers of weight gain in modern populations.
How Sleep Deprivation Disrupts Caloric Regulation
The primary mechanism is the ghrelin-leptin axis. Ghrelin (produced primarily in the stomach) signals hunger; leptin (produced by fat cells) signals satiety. A single night of reduced sleep (4–5 hours) increases ghrelin by approximately 28% and decreases leptin by approximately 18% — simultaneously increasing hunger signals and reducing satiety signals. The net effect is an increase in perceived hunger and caloric intake of approximately 300–500 calories per day, with the excess preferentially directed toward high-fat, high-carbohydrate foods. Over weeks and months, this systematic overconsumption drives weight gain independent of deliberate dietary choices.
The Mifflin-St Jeor Formula — Why We Use It
This calculator uses the Mifflin-St Jeor equation (1990), which is validated as the most accurate for most adult populations in multiple comparative studies. Male BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5. Female BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161. TDEE = BMR × activity multiplier. Individual variation is ±10–20% from formula estimates — use 2–4 weeks of actual intake and weight tracking to calibrate your personal TDEE.
Calorie Deficit — How Much Is Safe?
A deficit of 500 calories/day produces approximately 0.5 kg per week of weight loss — the rate generally considered safe and sustainable. Deficits above 700–1000 calories/day risk muscle loss, nutrient deficiencies, metabolic adaptation, and — critically — sleep disruption. Severe caloric restriction elevates cortisol and reduces REM sleep, which paradoxically impairs the leptin recovery needed to control hunger during a diet. Moderate, sustainable deficits with adequate sleep produce better long-term outcomes than aggressive restriction.
Calories — FAQ
How many calories do I need per day?
Your TDEE (Total Daily Energy Expenditure) depends on your size, age, sex, and activity level. Use this calculator for your personalized estimate. General ranges: sedentary adult women 1,600–2,000 kcal; sedentary adult men 2,000–2,600 kcal. These increase significantly with activity — a highly active person may need 3,000–4,000+ kcal. These are estimates — actual needs vary by ±10–20% between individuals at the same measured inputs.
Does sleep affect how many calories I burn?
Sleep deprivation reduces physical activity (fatigue lowers exercise motivation and output), which reduces TDEE. It also impairs thermoregulation efficiency and lean mass maintenance. More significantly, poor sleep increases caloric intake through the ghrelin-leptin mechanism — the net effect of chronic sleep restriction is increased caloric intake AND reduced energy expenditure, a double driver of weight gain. Improving sleep to 7–9 hours is genuinely one of the most impactful weight management interventions available.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest — just breathing, organ function, cellular maintenance. It represents approximately 60–70% of TDEE for sedentary people. TDEE (Total Daily Energy Expenditure) adds the thermic effect of food (~10% of intake) and physical activity (which varies widely). TDEE is the relevant number for weight management — eating at TDEE maintains weight, below loses, above gains.
How accurate are calorie calculators?
Formula-based TDEE estimates are typically within 10–20% of actual measured expenditure for most people. Individual variation is significant — genetics, gut microbiome, medication, medical conditions, and non-exercise activity (fidgeting, posture) all affect actual TDEE in ways formulas can't capture. The most accurate approach: use the formula as a starting point, track actual intake and weight weekly for 3–4 weeks, and adjust your target by 100–200 calories based on observed trends.
📋 Reviewed by: MySleepTool Editorial Team · Last updated: July 2026 · Sources: Mifflin MD et al. "A new predictive equation for resting energy expenditure" AJCN (1990), Spiegel K et al. "Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels" Annals of Internal Medicine (2004). Not medical advice.