How many calories should I eat a day?

Start with your resting burn (BMR)

Your basal metabolic rate is the energy your body uses just to stay alive at complete rest — breathing, circulation, temperature regulation and cell repair. It usually accounts for the majority of the calories you burn in a day, which is why it is the foundation of any estimate.

BMR is driven mainly by body size and composition. Larger bodies and bodies with more muscle mass burn more at rest. Age matters too: BMR tends to decline gradually with age, largely because lean mass tends to fall unless it is actively maintained.

Then multiply for activity (TDEE)

Total daily energy expenditure takes your BMR and scales it by an activity factor, from roughly 1.2 for a mostly sedentary day up to about 1.9 for a very active one. The multiplier is the part people get wrong most often, usually by overestimating how active an ordinary week really is.

The honest way to choose a factor is to think about a typical week, not your best week. A desk job with three gym sessions is not 'very active'. Most people land between 1.3 and 1.5, and that is entirely normal.

• Sedentary — desk work, little deliberate exercise — about 1.2
• Lightly active — light exercise 1-3 days a week — about 1.375
• Moderately active — moderate exercise 3-5 days — about 1.55
• Very active — hard exercise 6-7 days — about 1.725

The number is a starting point, not a rule

Every formula for BMR is an estimate built from population averages, and individual metabolism varies around it. Two people of the same height, weight, age and sex can genuinely have different actual needs. This is why the estimate is best treated as a hypothesis to test.

Track your intake and your weight for two to three weeks. If weight is stable and you are eating around your estimated maintenance level, the estimate was roughly right. If weight drifts, adjust by 100-200 calories and observe again rather than making a big correction.

Eating for a goal

For gradual weight loss, a deficit of roughly 10-20% below maintenance is a common starting range — large enough to make progress, small enough to be sustainable and to preserve muscle. Larger deficits work faster on paper but are harder to maintain and often cost lean mass.

For weight gain, a surplus of about 10-15% above maintenance supports steady gain without excessive fat accumulation. In both directions, protein intake and resistance training protect lean mass while your weight changes.

Why calories still matter even though food quality does

Calories determine whether weight changes; food composition strongly influences how you feel, how well you train and how easy the plan is to stick to. The two are not in competition. A calorie target with no attention to protein, fibre and micronutrients is technically correct and practically miserable.

The most sustainable approach is usually a moderate calorie target built around mostly unprocessed foods, with enough flexibility to include foods you enjoy. Adherence beats precision.