The question "how many calories should I eat" has a personal answer, not a universal one. It depends on your total daily energy expenditure (TDEE) — the sum of your basal metabolic rate, the energy you spend moving and the energy used to digest food. Let us calculate it in two minutes.
Step 1: your basal metabolic rate (BMR)
The Mifflin-St Jeor formula is the most accurate for the general population according to the Academy of Nutrition and Dietetics. You need your weight (kg), height (cm) and age:
- Men: (10 x weight) + (6.25 x height) - (5 x age) + 5
- Women: (10 x weight) + (6.25 x height) - (5 x age) - 161
- Example (woman, 70 kg, 165 cm, 35 yrs): 700 + 1031 - 175 - 161 = 1395 kcal BMR
Step 2: multiply by your activity (TDEE)
Your BMR is what you would burn lying in bed all day. Multiply it by your real activity factor to get your maintenance calories:
| Activity level | Factor | Example woman 70 kg | Example man 85 kg |
|---|---|---|---|
| Sedentary (desk, little exercise) | x1.2 | 1674 kcal | 2160 kcal |
| Light (1-3 days/week) | x1.375 | 1918 kcal | 2475 kcal |
| Moderate (3-5 days/week) | x1.55 | 2162 kcal | 2790 kcal |
| Active (6-7 days/week) | x1.725 | 2406 kcal | 3105 kcal |
Step 3: adjust for your goal
- Lose fat: TDEE minus 300-500 kcal (15-20% deficit)
- Maintain weight: your TDEE as is
- Build muscle: TDEE plus 200-300 kcal (slight surplus)
- Recomposition (lose fat and gain muscle at once): maintenance or a very small deficit + high protein + strength training
Renzy calculates your TDEE and calorie target automatically from your data, and adjusts the number based on your real week-by-week progress.
Scan your food with a photo. Calories, macros and micronutrients in 3 seconds.
Why protein comes before calories
Once you have your calorie number, the next step is not obsessing over every kcal but locking in your protein: 1.6-2.2 g per kg of body weight. In a deficit, protein decides whether you lose fat or muscle. Spread 25-40 g across each meal.
Step 4: measure reality, not the formula
Formulas have a 10% margin. The only way to know your real number is to log what you eat for 2-3 weeks and watch the weight trend (weekly average, not the daily reading). If you are not losing, cut 150-200 kcal. If you are dropping too fast or feel drained, add a little.
With Renzy you photograph your meals and the AI estimates calories and macros instantly, so you capture your real intake without weighing every ingredient. Then compare your weight trend against your goal to know whether you are on track or need to adjust.
Renzy calculates all of this for you
Scan your food with a photo. Calories, macros and micronutrients in 3 seconds.
