How many calories should I eat to lose weight?

Most adults lose weight with a daily target about 300–600 kcal below their current maintenance needs. There is no honest universal number. Your starting target depends on your body size, age, biological sex and ordinary activity—not the hardest workout you did last month.

A useful target does three things: it creates a real deficit, leaves enough food to cover nutrition and training, and feels repeatable on a Thursday when life is busy. Work out an estimate, follow it consistently for two weeks, then let your actual weight trend correct the math.

The short calculation

Start with resting energy expenditure, or BMR. The widely used Mifflin–St Jeor equation estimates the energy your body uses at rest:

• Male: 10 × weight in kg + 6.25 × height in cm − 5 × age + 5
• Female: 10 × weight in kg + 6.25 × height in cm − 5 × age − 161

Then multiply BMR by an activity factor to estimate total daily energy expenditure, or TDEE. A restrained set of starting factors is 1.2 for mostly sitting, about 1.45 for being on your feet and doing some planned exercise, and about 1.65 for training most days or doing physical work.

Finally, subtract a modest deficit. About 300 kcal a day is gentle. Around 500–550 kcal is a common middle setting. A larger deficit can move the scale faster, but it also leaves less room for protein, fiber, social meals and mistakes.

This is a starting estimate, not a metabolic fingerprint. The NIH Body Weight Planner uses a dynamic model because energy needs change as body weight changes; a fixed “3,500 calories equals one pound forever” calculation eventually overpromises.

A worked example

Take a 35-year-old woman who is 165 cm tall, weighs 78 kg and is on her feet a fair amount but does not train hard every day.

Her estimated BMR is:

10 × 78 + 6.25 × 165 − 5 × 35 − 161 = 1,475 kcal/day

Using a 1.45 activity factor:

1,475 × 1.45 = 2,139 kcal/day

That makes roughly 2,140 kcal her estimated maintenance intake. Subtracting 500 gives about 1,640 kcal/day for weight loss. Rounding to 1,650 makes the target easier to remember and does not meaningfully change the plan.

Imagine her first week averages 1,660 kcal, not exactly 1,650. That is excellent adherence. The useful question is not whether every day hit a bull's-eye; it is whether the weekly average and weight trend move in the intended direction.

Those are illustrations, not prescriptions. Two people at the same weight can differ because of height, age, lean mass, movement and estimation error.

Do not turn a floor into a goal

HeyCoach will not set an automated target below 1,200 kcal for women or 1,500 kcal for men. Those are conservative guardrails, not promises that those intakes are right for everyone. The NIDDK's Diabetes Prevention Program materials similarly say that eating below 1,200 kcal a day is not advised.

If the formula lands below the floor, do not squeeze harder. Use the floor, choose a slower rate, add movement if appropriate, or talk with a registered dietitian or clinician who can assess you personally. Children, teenagers, people who are pregnant or breastfeeding, people with a history of an eating disorder, and anyone managing a relevant medical condition should not use a generic online calculation as a treatment plan.

Feeling persistently dizzy, cold, exhausted, preoccupied with food or driven to compensate for eating is not a sign to become “more disciplined.” It is a reason to stop tightening the target and get qualified help.

Why two calculators disagree

Usually, the equations are not the main disagreement. The activity setting is.

For the example above, a 1.2 multiplier produces maintenance around 1,770 kcal. A 1.55 multiplier produces about 2,290. That 520-kcal gap is larger than the proposed deficit. A person with a desk job and three gym sessions can easily select “very active” because the workouts feel hard, even though most of the week's 168 hours are sedentary.

Use the lower plausible activity level unless your job keeps you moving or you have measured evidence that the higher one fits. Do not add every exercise calorie back on top if the activity multiplier already includes your usual exercise. That counts the same movement twice.

There is also normal model error. Predictive equations estimate population averages; they cannot see your body composition or spontaneous movement. Labels, recipes and restaurant portions add error on the intake side too. That is why the first number is a testable hypothesis.

Let two weeks of real data improve the target

For 14 days, log as consistently as you reasonably can. Weigh under similar conditions—morning, after the bathroom and before breakfast works well—and compare weekly averages rather than single weigh-ins.

Then use this decision:

• If the average is moving at a comfortable rate and hunger is manageable, keep the target.
• If it is flat, audit the log before cutting food. Check oils, dressings, drinks, bites while cooking and weekend meals.
• If the log is sound and the four-week trend is still flat, reduce by a small 100–200 kcal or add sustainable movement.
• If weight is falling too quickly, performance is collapsing or hunger dominates the day, add calories.

The CDC describes gradual loss of roughly one to two pounds per week as more maintainable than faster loss, but even that range is too aggressive for some smaller people. A percentage can be more useful: many people aim below about 1% of body weight per week, with slower often easier to sustain.

Learn the logging part in how to count calories without hating it and troubleshoot a stubborn trend with why you may not be losing weight in a calorie deficit.

FAQ

Is 1,500 calories enough to lose weight?

It creates a deficit only if your maintenance needs are above 1,500. For one person it may be unnecessarily low; for another it may be near maintenance. Calculate a starting estimate, respect the safety floor and use a multi-week weight trend to adjust.

Should I eat the same calories every day?

You do not have to. A steady target is simple, but a weekly budget works too: for example, 1,600 on five days and 1,850 on two days averages about 1,670. Avoid saving so much for the weekend that weekdays become punishing.

How soon should I lower my calories if the scale does not move?

Not after two or three noisy weigh-ins. Hold the plan for at least two consistent weeks, and preferably compare two weekly averages. Menstrual-cycle changes, sodium, carbohydrate intake, constipation and a new workout can temporarily hide fat loss.

Sources

• Mifflin et al., the original resting-energy equation study
• NIDDK Body Weight Planner
• NIDDK guidance on calorie levels and the 1,200-kcal lower limit
• CDC steps for gradual, sustainable weight loss

The easy way to do this

HeyCoach asks for the same few inputs, works out your calorie and protein targets in about 30 seconds, and keeps the lower limits built in. From there, a meal is one sentence or one photo in WhatsApp—not another dashboard to maintain. Two weeks later, ask how your week went and adjust from evidence instead of guessing.