Your daily calorie requirement is determined in two steps:
Step 1: Calculate Basal Metabolic Rate (BMR) — the energy your body needs at complete rest to maintain vital functions (breathing, circulation, cell repair).
Our calculator uses the Mifflin-St Jeor equation (1990), the most validated formula for most adults:
Example: A 35-year-old woman, 165 cm, 65 kg:
BMR = (10 × 65) + (6.25 × 165) − (5 × 35) − 161 = 650 + 1,031.25 − 175 − 161 = 1,345 calories/day
Step 2: Multiply by Activity Factor (Harris-Benedict) to get Total Daily Energy Expenditure (TDEE):
TDEE = 1,345 × 1.55 (moderately active) = 2,085 calories/day
Choosing the right activity multiplier is crucial — most people underestimate their activity level, but desk workers often overestimate it:
| Activity Level | Multiplier | Description | Examples |
|---|---|---|---|
| Sedentary | 1.2 | Little or no exercise | Desk job, no formal exercise |
| Lightly Active | 1.375 | Light exercise 1–3 days/week | Walking, light yoga 1–3×/week |
| Moderately Active | 1.55 | Moderate exercise 3–5 days/week | Gym 3–5×/week, cycling to work |
| Very Active | 1.725 | Hard exercise 6–7 days/week | Daily intense training, manual labor |
| Extremely Active | 1.9 | Very hard exercise, physical job | Elite athletes, construction workers |
If your TDEE seems too high, try the next lower activity level. Many people classify themselves as "very active" when their actual exercise burns only 200–300 extra calories per day, which is closer to "moderately active."
Weight loss requires a calorie deficit — burning more than you consume. One pound of fat is approximately 3,500 calories, so:
However, deficits beyond 1,000 calories/day are not recommended without medical supervision. Very low intake causes muscle loss, metabolic adaptation, and micronutrient deficiencies.
Minimum intake guidelines:
Metabolic adaptation: After weeks of dieting, your body lowers its BMR by 10–15% as an adaptive response. This is why weight loss slows over time. Strategies to counter this include: diet breaks (2 weeks at maintenance), refeeds (periodic higher-carb days), and resistance training to preserve muscle mass.
Example weight loss plan: Woman with TDEE 2,085 calories sets a goal of 1,585 calories/day (500 deficit). Expected loss: ~0.5 kg/week, reaching −5 kg goal in about 10 weeks.
Calorie density refers to calories per gram of food. Choosing low-density foods lets you eat larger volumes while staying in a deficit:
| Food | Calories per 100g | Density |
|---|---|---|
| Cucumber / Celery | 12–16 kcal | Very Low |
| Broccoli / Spinach | 25–35 kcal | Very Low |
| Strawberries / Oranges | 30–50 kcal | Low |
| Chicken breast (lean) | 165 kcal | Moderate |
| Brown rice (cooked) | 215 kcal | Moderate |
| Bread (whole wheat) | 247 kcal | Moderate-High |
| Cheddar cheese | 402 kcal | High |
| Almonds / Nuts | 580–620 kcal | Very High |
| Olive oil / Butter | 880–900 kcal | Extremely High |
Building meals around low-calorie-density vegetables, lean proteins, and whole grains allows you to eat satisfying volume without exceeding your calorie target.
Calories come from three macronutrients, each with different roles and calorie densities:
Sample macro splits for different goals (based on 2,000 calories):
| Goal | Protein | Carbs | Fat |
|---|---|---|---|
| Weight loss | 30% (150g) | 40% (200g) | 30% (67g) |
| Muscle building | 25% (125g) | 45% (225g) | 30% (67g) |
| Endurance athlete | 20% (100g) | 55% (275g) | 25% (56g) |
| Ketogenic | 20% (100g) | 5% (25g) | 75% (167g) |
Exercise burns far fewer calories than most people think — and less than fitness trackers often suggest (typically overestimating by 30–50%). Here are evidence-based estimates for a 70 kg adult:
| Activity | Duration | Approx. Calories Burned |
|---|---|---|
| Walking (5 km/h) | 30 min | 150 kcal |
| Running (10 km/h) | 30 min | 320 kcal |
| Cycling (moderate) | 30 min | 270 kcal |
| Swimming (freestyle) | 30 min | 290 kcal |
| Weight training | 45 min | 200–250 kcal |
| HIIT | 25 min | 280–350 kcal |
| Yoga | 60 min | 180–250 kcal |
Important nuance: weight training burns fewer calories during the session than cardio, but increases resting metabolic rate for 24–48 hours afterward ("afterburn" or EPOC — Excess Post-exercise Oxygen Consumption). This makes resistance training highly effective for long-term calorie management.
"Energy intake should be in balance with energy expenditure. Evidence indicates that total fat should not exceed 30% of total energy intake to avoid unhealthy weight gain in the general population."
Most adults need between 1,600 and 3,000 calories per day depending on age, sex, weight, height, and activity level. Use the Mifflin-St Jeor equation for a personalized estimate. Sedentary women typically need 1,600–2,000 kcal; active men up to 3,000+ kcal.
A 1990 equation that estimates Basal Metabolic Rate (BMR) — calories needed at rest. For men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5. For women: same but minus 161 instead of +5. Studies show it is the most accurate BMR formula for most non-athlete adults.
Calorie counting works but is not the only approach. It creates awareness and accountability. For sustainable results, combine moderate calorie tracking with high-protein foods, plenty of vegetables, and regular exercise. Tracking for 2–4 weeks teaches portion sizes, after which many people can maintain a deficit by feel.
Approximately 3,500 calories equals one pound (0.45 kg) of body fat. To lose one pound per week, create a daily deficit of 500 calories. Note: in practice, weight loss varies due to water retention, muscle changes, and metabolic adaptation.
Common reasons: (1) underestimating food intake — cooking oils, sauces, and bites add up quickly; (2) overestimating exercise burn; (3) metabolic adaptation — your body lowers BMR after weeks of dieting; (4) water retention masking fat loss, especially with high sodium or new exercise. Recheck your logging accuracy and consider a 2-week diet break.
BMR is the calories you burn completely at rest. TDEE (Total Daily Energy Expenditure) includes BMR plus calories burned through all physical activity. TDEE = BMR × activity multiplier. TDEE is your maintenance calorie level — eating at TDEE maintains your current weight.
To build muscle (bulking), aim for a caloric surplus of 200–500 calories above TDEE, combined with high protein intake (1.6–2.2g per kg body weight) and progressive resistance training. A surplus of 300 calories/day leads to gradual lean muscle gain while minimizing fat accumulation.
Yes, to an extent. Protein and fiber-rich foods have higher thermic effect (the body burns ~20–30% of protein calories just digesting it, vs ~6% for carbs and ~3% for fat). High-protein, high-fiber foods also increase satiety hormones and reduce hunger, making it easier to maintain a deficit.