How do I calculate my calorie needs?

Your calorie needs are calculated in two steps: First, your Basal Metabolic Rate (BMR) is determined — the calories your body burns at rest. Then, this is multiplied by an activity factor (PAL) to get your Total Daily Energy Expenditure (TDEE). Our calculator uses the Mifflin-St Jeor formula by default and optionally the Katch-McArdle formula if you know your body fat percentage.

What is the difference between BMR and TDEE?

BMR (Basal Metabolic Rate) is the energy your body needs at complete rest to maintain vital functions like breathing, heartbeat, and cell regeneration. TDEE (Total Daily Energy Expenditure) additionally includes calories burned through movement, exercise, digestion (thermic effect of food), and general activity. For dieting or meal planning, TDEE is the relevant metric.

How many calories do I need to lose weight?

To lose weight, you need to consume fewer calories than your TDEE. A moderate deficit of 500 kcal per day leads to weight loss of about 0.5 kg per week. We recommend never going below your BMR and keeping the deficit between 300-750 kcal daily to lose weight sustainably without muscle loss.

What is the Mifflin-St Jeor formula?

The Mifflin-St Jeor formula is the most commonly recommended equation for calculating BMR today. Developed in 1990, it is considered the most accurate formula for most people. For men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age(years) + 5. For women: same formula but -161 instead of +5. It accounts for gender, weight, height, and age.

How accurate is a calorie calculator?

Calorie calculators provide a good estimate with approximately 80-90% accuracy for most people. The Mifflin-St Jeor formula has an average deviation of about 10% from actual BMR. Factors like genetics, hormones, medications, and body composition can influence actual needs. If you enter your body fat percentage, the more accurate Katch-McArdle formula is used.

Should I eat below my BMR?

No, you should never eat below your BMR consistently. BMR only covers vital body functions. Calorie intake below BMR can lead to muscle loss, nutrient deficiency, metabolic slowdown, and hormonal imbalances. Our calculator sets a floor of 1,200 kcal. A moderate deficit below TDEE but above BMR is the safe approach.

How much protein do I need per day?

We recommend 1.8 g protein per kilogram of body weight per day. For muscle building (goal: gain weight), we increase the recommendation to 2.0 g/kg. Protein is crucial for muscle maintenance, satiety, and the thermic effect of food. At 75 kg body weight, that means 135 g protein daily — about 540 kcal from protein alone.

How often should I recalculate my calorie needs?

You should recalculate every 4-6 weeks, especially if your weight has changed by more than 2-3 kg, you've changed your training program, or you've hit a plateau. As body weight decreases, your BMR also decreases, so you need fewer calories than at the start of your diet.

Are 1,200 calories per day enough?

1,200 kcal per day is the absolute minimum and only suitable for very small, light, and inactive individuals. For most people, this intake is too low and can lead to nutrient deficiencies. Women should consume at least 1,400-1,600 kcal and men at least 1,600-1,800 kcal daily. Our calculator considers your individual measurements and never sets an extreme deficit.

How does exercise affect my calorie needs?

Exercise significantly increases your TDEE. Depending on activity level, your BMR is multiplied by a PAL factor: Sedentary (1.2), Lightly active (1.375), Moderately active (1.55), Very active (1.725), Extremely active (1.9). Additionally, our calculator accounts for daily steps: above 7,000 steps, you get a bonus of 0.04 kcal per extra step. This accurately captures everyday movement too.

Calorie Needs and Age: How Your Metabolism Changes Over Time | Calorie Calculator

Calorie Needs and Age: Why Your Metabolism Changes

As you age, your calorie needs decrease. But why exactly? And what can you do about it? In this article, we explain the biological mechanisms behind metabolic decline and offer practical tips to keep your energy expenditure high even as you age.

How BMR Changes with Age

BMR decreases from age 20 by an average of 1-2% per decade. That sounds small but adds up: a 50-year-old has a daily need about 100-200 kcal lower than a 25-year-old with the same body composition. Over a year, that is a difference of 36,500-73,000 kcal -- equivalent to 5-10 kg of body fat.

The Main Cause: Muscle Loss (Sarcopenia)

The most important reason for declining metabolism is age-related muscle loss. From age 30, without targeted strength training, humans lose about 3-8% of muscle mass per decade. Since muscle tissue is more metabolically active than fat tissue (about 13 kcal/kg/day vs. 4.5 kcal/kg/day), less muscle means lower BMR.

Hormonal Changes

Hormone levels change with age: testosterone decreases in men from 40 by about 1% per year. Estrogen drops significantly in women during menopause. Growth hormone declines from age 30. Thyroid hormones can change. All these hormones directly influence metabolism.

What You Can Do About It

**Strength training is the most important lever.** Regular strength training (2-3x per week) can not only stop age-related muscle loss but reverse it. Studies show that even 70-year-olds can significantly increase their muscle mass and strength.

**Sufficient protein.** Older adults tend to need more protein than younger ones to trigger the same muscle protein synthesis. The International Society of Sports Nutrition recommends at least 1.2 g/kg from age 50, preferably 1.6-2.0 g/kg with active strength training.

**Stay active.** NEAT (everyday movement) often declines with age more than BMR does. Conscious walking, taking stairs, and everyday activity are crucial.

Calorie Needs Across Life Stages

- **20-30 years:** Highest BMR, high activity. Men: 2,400-3,000 kcal, Women: 1,800-2,400 kcal.

- **30-50 years:** Slight decline. Men: 2,200-2,800 kcal, Women: 1,700-2,200 kcal.

- **50-70 years:** Noticeable decline. Men: 2,000-2,600 kcal, Women: 1,600-2,000 kcal.

- **70+ years:** Men: 1,800-2,400 kcal, Women: 1,500-1,900 kcal.

These are averages and can vary significantly based on activity level and body composition.

Conclusion

Age-related metabolic decline is real but not inevitable. With strength training, adequate protein, and an active lifestyle, you can maintain your BMR and prevent the yo-yo effect in later years. Recalculate your calorie needs regularly and adjust your diet to your changing requirements.