Every body-composition goal comes back to the same question: how much should I eat? This guide shows how to estimate your energy needs, set a target for your goal, split it into protein, fat and carbohydrate, and adjust when reality differs from the estimate.
Step 1: Estimate your BMR
Basal metabolic rate (BMR) is the energy your body uses at rest to keep you alive: breathing, circulation, temperature and organ function. Three formulas are common:
Mifflin-St Jeor (recommended for most people)
- Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
- Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
Harris-Benedict (revised) is an older equation that tends to give slightly higher results.
Katch-McArdle uses lean body mass: BMR = 370 + 21.6 × lean mass (kg). It is useful if you know your body fat.
Example: a 32-year-old man, 178 cm and 88 kg: 10 × 88 + 6.25 × 178 − 5 × 32 + 5 = 880 + 1112.5 − 160 + 5 = 1,837 kcal.
Step 2: Multiply by activity to find TDEE
Total daily energy expenditure (TDEE) is BMR plus the energy from movement, exercise and digesting food.
| Activity level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, little exercise |
| Lightly active | 1.375 | Exercise 1 to 3 days a week |
| Moderately active | 1.55 | Exercise 3 to 5 days a week |
| Very active | 1.725 | Hard exercise 6 to 7 days a week |
| Extra active | 1.9 | Physical job plus daily training |
Continuing the example: 1,837 × 1.55 = about 2,850 kcal. Most people overestimate their activity, so if you are unsure, pick the lower level.
These numbers are starting points. Real needs vary by roughly 10 percent from the equations because of genetics, non-exercise movement and body composition. Track your weight for two weeks and adjust.
Step 3: Choose a target for your goal
| Goal | Target calories | Typical rate |
|---|---|---|
| Lose fat | 10 to 20% below TDEE | 0.5 to 1% of body weight per week |
| Maintain | About TDEE | Stable weight |
| Build muscle | 5 to 10% above TDEE | 0.25 to 0.5% of body weight per week |
| Recomposition | About TDEE or a small deficit | Slow, with strength gains |
Never plan below safe minimums (commonly about 1,200 kcal for women and 1,500 for men) without medical supervision. Faster deficits cost more muscle and are hard to sustain.
Step 4: Set your macros
Protein first. Protein preserves and builds muscle, is the most filling macronutrient and has a higher thermic effect.
- 1.6 to 2.2 g per kg of body weight per day for people who train. A meta-analysis of resistance-training trials found benefits levelling off around 1.6 g/kg on average, with an upper confidence limit near 2.2 g/kg.
- In a calorie deficit, the higher end helps hold on to muscle.
Fat next. Fat supports hormones and absorbs vitamins. A floor of about 0.6 to 1 g per kg, or 20 to 35 percent of calories, is a typical range.
Carbohydrate fills the rest. Carbs fuel training and are flexible. If you train hard, do not cut them too low. If you prefer lower carbs, keep protein high and fibre adequate.
Fibre: about 14 g per 1,000 kcal is a common target.
Each gram of protein and carbohydrate provides about 4 kcal, fat about 9 kcal, and alcohol about 7 kcal.
Example: 2,300 kcal goal for an 88 kg lifter in a deficit.
- Protein: 2.0 × 88 = 176 g = 704 kcal
- Fat: 27% of 2,300 = 621 kcal = about 69 g
- Carbohydrate: the remaining 975 kcal = about 244 g
Step 5: Track and adjust
- Weigh yourself daily (or three or four times a week) under the same conditions and use the weekly average.
- Compare the trend to your goal. If weight is not moving as planned after two weeks, adjust by about 100 to 200 kcal, or add steps.
- Watch other signals. Waist, photos, strength and energy matter as much as scale weight.
- Take diet breaks. After 8 to 12 weeks of dieting, a week at maintenance can help adherence and recovery.
Practical tips
- Base your meals on protein plus vegetables or fruit plus a carb source. Then add fats deliberately.
- Weigh food for two weeks to calibrate your eye. Restaurant and packaged foods vary; expect estimates to be off by 10 to 20 percent.
- Do not cut foods you love completely. Plans you can live with beat perfect ones you cannot.
- Drink water. 2 to 3 litres a day is a reasonable guide, more with heavy sweating.
- Alcohol counts. It adds calories and affects sleep and recovery.
Who should get professional help
If you are under 18, pregnant or breastfeeding, have diabetes or another medical condition, take medication that affects weight or appetite, or have a history of disordered eating, get individual guidance from a doctor or registered dietitian. The calculators here are educational, and they cannot account for your medical history.
Your personal Body Report includes a calorie and macro plan alongside your measurements and a four-week protocol.