How Many Calories Should I Eat to Lose Weight?
A calorie target is arithmetic plus feedback — the estimate gets you started, and what actually happens over the next few weeks tells you whether it was right.
By the HealthMedHub Editorial Team · Published October 2026 · Reviewed for accuracy against WHO, NIH, and NHS sources · Our review process
How Weight Loss Actually Works
Body weight is the net result of energy in and energy out. Eat more than you expend and the surplus is stored, mostly as fat; eat less and the body draws on stored energy. This is the energy-balance principle, and it is not seriously disputed. What is disputed is how precisely it can be applied to one person, because both sides of the equation are estimates rather than measurements.
The World Health Organization frames weight management in terms of a healthy diet and adequate physical activity rather than a single calorie number, and that framing is worth keeping in mind. A calorie target is a planning tool, not a law of nature. The practical rule is simple: a moderate, sustainable deficit produces gradual loss, a severe one produces faster loss followed by fatigue, muscle loss, and a return to old habits.
One point that is often missed: the energy-balance equation adjusts as you lose weight. A lighter body burns fewer calories for the same activity, and a deficit that produced steady loss in month one tends to stall in month three. Any workable plan therefore includes a review point, not just a starting number.
If you have a history of an eating disorder, are pregnant, are under 18, or are managing a chronic condition such as diabetes, do not set a calorie target from a general article. Speak to a clinician or dietitian first — the guidance below is aimed at healthy adults.
It is also worth separating weight loss from health improvement, because they are not the same goal. Losing weight is not automatically beneficial and is not always the right objective; improving diet quality, fitness, sleep, and strength can improve health markers substantially with modest or no weight change. Framing the exercise as changing body composition rather than simply reducing a number on a scale tends to produce better long-term outcomes and a far healthier relationship with food.
Step 1: Estimate Your Maintenance Calories
Before choosing a target, work out roughly how many calories you currently burn in a day. This is your maintenance level, sometimes called total daily energy expenditure. Two components matter: your resting metabolic rate, which is the energy used just to stay alive, and your activity level, which multiplies it upward.
The most widely used clinical equations for resting rate are Mifflin-St Jeor for adults and the Schofield equations for children, both recommended by the NHLBI for weight assessment and planning. Rather than working through the arithmetic by hand, the Calorie Calculator applies the equation along with an activity multiplier and returns a maintenance figure.
Treat that number as a starting hypothesis with a margin of error of perhaps 10 to 15 percent. Two people of identical age, sex, height, and weight can differ meaningfully in resting rate because of body composition and genetics. The estimate is useful precisely because it is close enough to be a sensible starting point, and because the feedback loop in the next few weeks will correct it.
A shortcut worth knowing: the TDEE Calculator expresses the same idea, and the difference between your maintenance figure and your intake target is your deficit. Keeping the two numbers separate makes it much easier to adjust one without losing track of the other.
Step 2: Choose a Safe Deficit
One kilogram of body fat stores roughly 7,700 kilocalories, and a pound stores roughly 3,500. That converts a target rate of loss into a daily deficit. Losing 0.5 kg (about 1 lb) a week requires a deficit of roughly 500 kilocalories a day. Losing 0.25 kg a week requires roughly 250 a day.
Guidance from the NHLBI points toward gradual loss, and clinical practice generally treats 0.5 to 1 kg a week as a sensible upper range for most adults. Deficit sizes above roughly 1,000 kilocalories a day are difficult to sustain, increase the proportion of weight lost as muscle, and raise the risk of inadequate intake of protein, iron, calcium, and other micronutrients.
There is also a floor worth respecting. The NHS notes that the reference intake for an average adult is around 2,000 kilocalories a day for women and 2,500 for men, and that these figures vary with age, size, and activity. Very low intakes should only be undertaken with clinical supervision.
If your calculated deficit would take you below about 1,200 kilocalories a day as a woman or 1,500 as a man, the better move is to increase activity rather than cut food further, or to accept slower loss. A smaller deficit that you can hold for six months will outperform a larger one you abandon in three weeks.
Step 3: Track, Then Adjust
Set your target, hold it reasonably consistently for two to three weeks, and compare average body weight at the start and end of that period. Daily weight fluctuates by one to two kilograms with food, fluid, glycogen, and sodium, so a single reading is close to meaningless. Weigh yourself at the same time each day, ideally in the morning, and average the week.
If your weekly average has fallen by roughly the rate you intended, the estimate was good and nothing needs to change. If it has not moved after three weeks, your maintenance estimate was too high or your intake was higher than recorded — reduce the target by 100 to 200 kilocalories and reassess. If you are losing faster than about 1 kg a week after the first fortnight, add calories back.
The first week or two behaves differently from the rest, because early weight loss includes water and glycogen as well as fat. This is why the adjustment check should start only after the initial drop has settled, otherwise you will reduce a target that was already working.
Portion drift is the most common reason progress stalls. Estimating intake without measuring tends to under-report by a meaningful margin, and cooking oils, drinks, sauces, and snacks are the usual culprits. You do not need to weigh food forever, but a week of honest measurement every few months is a cheap way to recalibrate your eye.
Why the Arithmetic Rarely Matches Exactly
The 7,700-kilocalorie figure is a useful approximation with an important caveat: it describes the energy content of body fat, not the energy your body will necessarily liberate per kilogram lost. As weight comes off, resting metabolic rate falls, the cost of carrying a lighter body around falls, and the deficit narrows without any change in behaviour. This is why loss slows over time even when nothing about the plan changes.
There is also the composition question. Without adequate protein and resistance training, a larger share of weight lost comes from muscle rather than fat, which lowers metabolic rate further and works against long-term maintenance. Protein intake of roughly 1.2 to 1.6 grams per kilogram of body weight a day is commonly used to support lean mass during a deficit; the Protein Calculator can translate that into grams, and our guide to macros puts protein in the context of total intake.
Finally, adherence beats precision. A plan that is 90 percent accurate and followed for a year outperforms a perfect calculation abandoned in a month. The most useful things you can do are choose a moderate deficit, eat mostly whole foods, keep protein adequate, and review every few weeks rather than daily. If weight is not moving in the direction you want after a genuine effort, treat it as information about the estimate, not a personal failing.
One last consideration is where those calories come from. A deficit achieved by cutting protein, vegetables, and fibre while keeping refined carbohydrates and alcohol tends to produce hunger, poor satiety, and muscle loss. The same deficit built from lean protein, legumes, vegetables, fruit, and whole grains is considerably easier to sustain and preserves lean mass better. The WHO healthy diet guidance is a reasonable template: plenty of vegetables and fruit, whole grains, limited free sugars and salt, and fats shifted toward unsaturated sources.
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