Nutritional guide
Calories, BMR and TDEE explained
Understanding your energy expenditure is the first step for any body composition goal, whether losing fat, maintaining or gaining muscle.
What is TDEE
TDEE (Total Daily Energy Expenditure) is the total calories you spend each day, including basal metabolism, digestion (thermic effect) and all your physical activity. It is the reference number for planning your diet.
Mifflin-St Jeor Formula
Published in 1990, it is the most accurate for adults according to the US Academy of Nutrition and Dietetics with a margin of error of ±10%.
Man: 10×P + 6.25×A – 5×E + 5
Woman: 10×P + 6.25×A – 5×E – 161
P=weight(kg), H=height(cm), A=age
How to use the result
To lose fat sustainably, subtract 300–500 kcal from your TDEE. To gain muscle, add 200–500 kcal. To maintain weight, eat exactly your TDEE. Adjust every 2–4 weeks based on progress.
What is BMR?
Basal Metabolic Rate (BMR) is the minimum energy your body needs at complete rest to maintain vital functions: breathing, circulation, thermal regulation and organ function. It represents 60–75% of total daily caloric expenditure.
Harris-Benedict Formula
Developed in 1919 and revised in 1984, it is the second reference formula. Slightly less accurate than Mifflin in modern populations, but widely used clinically.
Man: 88.36 + 13.4×P + 4.8×A – 5.68×E
Woman: 447.6 + 9.25×P + 3.1×A – 4.33×E
P=peso(kg), A=altura(cm), E=edad
Factors that affect BMR
- Muscle mass: muscle uses more energy at rest than fat.
- Age: BMR decreases with age as muscle mass is lost.
- Thyroid hormones: hypothyroidism significantly reduces BMR.
Frequently asked questions
All About Daily Calories
Evidence-based answers about calories, BMR, TDEE and weight loss.
It depends on your weight, height, age, sex and activity level. The average ranges from 1,600 to 2,500 kcal/day for women and 2,000 to 3,000 kcal/day for men. Our calculator computes your personalised TDEE using the Mifflin-St Jeor formula, the most widely recommended standard today.
BMR is the number of calories your body needs at complete rest (without moving) to maintain vital functions: breathing, circulation, body temperature, cellular synthesis and organ function. It represents approximately 60–75% of total daily energy expenditure.
BMR (Basal Metabolic Rate) is the caloric expenditure at complete rest. TDEE (Total Daily Energy Expenditure) also includes energy spent on daily physical activity, the thermic effect of food (~10%) and other activities. TDEE is always higher than BMR and is the number you should use to plan your diet.
A deficit of 500 kcal/day produces an approximate loss of 0.5 kg per week, which is sustainable and safe for most people. A deficit of 1,000 kcal/day may allow losing up to 1 kg/week, but should be done under medical supervision to avoid muscle loss and nutritional deficiencies. It is not recommended to go below 1,200 kcal/day for women or 1,500 for men.
Yes. Published in 1990 by Mifflin and St Jeor, it is the most accurate formula for estimating BMR in adults according to the US Academy of Nutrition and Dietetics, with a margin of error of approximately ±10%. It surpasses the Harris-Benedict formula (1919) in accuracy and is the most recommended in clinical and sports settings today.
Muscle tissue uses more energy at rest than fat tissue. For every additional kilogram of muscle, basal metabolism increases by approximately 13 kcal/day. Although the individual effect is modest, muscle mass also increases expenditure during activity. That is why strength training is key for a more active and sustainable metabolism in the long term.
For a 30-year-old adult woman, 65 kg and 165 cm, the BMR (Mifflin-St Jeor) is approximately 1,410 kcal/day. For a 30-year-old adult man, 80 kg and 178 cm, the BMR is around 1,900 kcal/day. Values vary significantly by weight, height, age and body composition. Use our calculator to get your exact value.
In addition to weight, BMR depends on body composition: two people of the same weight with different muscle-to-fat ratios will have different BMRs, because muscle tissue uses more energy at rest. Genetics, thyroid hormones, ambient temperature and long-term nutritional status also play a role.
Yes. Strength training is the most effective strategy for increasing BMR in the long term, as it increases muscle mass. Eating enough protein (1.6–2.2 g/kg) helps preserve muscle. Avoiding very restrictive diets is key: the body reduces BMR as an adaptation to severe caloric deficits (metabolic adaptation), making weight loss harder.
It is recommended not to eat below BMR × 1.2 (sedentary level), which represents the viable minimum for a healthy adult. Eating less can cause muscle loss, chronic fatigue and metabolic slowdown. A safe and sustainable deficit is 300–500 kcal below TDEE, never below 1,200 kcal/day for women or 1,500 kcal/day for men.
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