How Many Calories Do I Need a Day? BMR, TDEE and Calorie Targets for Weight Loss

Calories are a measure of energy. The food you eat provides calories, and your body uses them to keep you alive, move and think. Eat more than you use and you gain weight; eat less and you lose weight. Knowing roughly how many calories you need makes it easier to plan meals, lose weight safely or gain healthily.

The three parts of calorie use

1. Basal metabolic rate (BMR): about 60-70% of your daily energy. It is the energy needed for breathing, circulation, brain function and keeping warm at complete rest.
2. Physical activity: about 15-30% for most people, including exercise and daily movement such as walking, housework and fidgeting.
3. Thermic effect of food: about 10%, the energy used to digest and absorb food.

The sum is your total daily energy expenditure (TDEE). This is the number of calories you need to maintain your weight.

Calculating BMR

The Mifflin-St Jeor equation is widely used:

• Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
• Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Example: a woman aged 35, 160 cm tall and weighing 65 kg has a BMR of (650) + (1,000) − (175) − 161 = about 1,314 kcal.

From BMR to TDEE: activity factors

Multiply BMR by an activity factor:

• Sedentary (desk job, little exercise): × 1.2
• Lightly active (light exercise 1-3 days a week): × 1.375
• Moderately active (moderate exercise 3-5 days a week): × 1.55
• Very active (hard exercise 6-7 days a week): × 1.725
• Extremely active (physical job plus training): × 1.9

For the woman above, if lightly active: 1,314 × 1.375 = about 1,807 kcal per day to maintain weight.

Skip the maths with our TDEE calorie calculator. These formulas are estimates, and real needs can differ by 10-15%. Track your weight for 2-3 weeks and adjust.

Calorie targets for different goals

• Maintain weight: eat close to your TDEE.
• Lose weight slowly: eat about 250-500 kcal below TDEE for loss of about 0.25-0.5 kg weekly.
• Faster loss: up to 750 kcal deficit may be used under supervision for people with higher BMI.
• Gain weight or build muscle: eat 250-500 kcal above TDEE with enough protein and strength training.
• Pregnancy and breastfeeding: needs rise, roughly +200-350 kcal in the second and third trimesters and +300-500 kcal while breastfeeding. Follow antenatal advice, and do not diet.

As a general safety rule, do not go below your BMR or about 1,200 kcal (women) / 1,500 kcal (men) without medical supervision.

Calories in common foods (approximate)

• 1 cup cooked white rice (about 160 g): 200-210 kcal
• 1 whole-wheat roti (medium): 100-120 kcal
• 1 slice of bread: 70-80 kcal
• 1 string hopper: about 40-50 kcal
• ½ cup cooked dhal: 100-130 kcal
• 1 boiled egg: about 75 kcal
• 100 g cooked fish or chicken breast: 130-180 kcal
• 1 medium banana: about 100 kcal
• 1 teaspoon oil: about 40 kcal
• 1 tablespoon sugar: about 50 kcal
• 1 cup sweetened tea with 2 teaspoons sugar: about 35-50 kcal
• 1 can of soft drink (330 mL): about 140 kcal
• 1 vegetable roll or cutlet (fried): 150-250 kcal
• 1 tablespoon of thick coconut milk: about 30-40 kcal

Values vary by recipe and portion. Liquid calories and oil add up quickly. Learn more about food choices in how to lose weight safely.

Calories are not everything

• Quality matters: 200 calories of vegetables and pulses affect hunger and blood sugar very differently from 200 calories of sweets.
• Protein and fibre help you feel full. Check your protein needs with our protein calculator.
• Muscle raises BMR, so strength training helps long term.
• Age and sex: BMR falls with age and is lower in women, who usually have less muscle.
• Genetics, hormones and medicines (such as steroids and insulin) also influence weight.

Should you count calories?

Counting can help for a few weeks to learn portion sizes, but it is not for everyone. If it triggers anxiety or unhealthy behaviour, or if you have a history of eating disorders, use portion-based methods such as the plate method instead.

Common mistakes

• Overestimating exercise calories and "eating them back"
• Not counting drinks, cooking oil, coconut milk and snacks
• Eating too little during the week and overeating at weekends
• Expecting steady weekly loss; weight fluctuates by 1-2 kg from water and salt

Underweight and low calorie intake

If your BMI is below 18.5, or you are losing weight without trying, see a doctor to check for causes such as thyroid disease, infection, diabetes, digestive or mental health conditions. Use our BMI calculator and see BMI for Asians.

When to see a doctor or dietitian

See a registered dietitian if you have diabetes, kidney disease or heart disease, are pregnant, are an athlete, have lost or gained weight rapidly, or want a personalised plan.

References

• Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990
• FAO/WHO/UNU: human energy requirements
• World Health Organization: healthy diet fact sheet
• Sri Lanka Ministry of Health, Nutrition Division: food-based dietary guidelines