There is no single right number. Your daily calorie need depends on your size, your age and how much you move — and the honest version of the answer is a range you adjust once you have two weeks of real data. Here is how to find your starting point in about two minutes.
Your basal metabolic rate is the energy your body spends keeping you alive: breathing, pumping blood, holding temperature. It is the biggest single piece of your daily total, usually 60–70% of it. The Mifflin-St Jeor equation is the one most dietitians reach for, because it is the most accurate of the simple formulas for the general population: - Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5 - Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161 A 32-year-old woman at 68 kg and 168 cm gets (10 × 68) + (6.25 × 168) − (5 × 32) − 161 = 1,409 kcal. That is what she would burn spending the entire day asleep.
Nobody spends the day asleep. Multiply your BMR by an activity factor to get your TDEE — total daily energy expenditure, the number of calories that keeps your weight stable: - 1.2 — desk job, little deliberate exercise - 1.375 — light exercise 1–3 days a week - 1.55 — moderate exercise 3–5 days a week - 1.725 — hard exercise 6–7 days a week - 1.9 — hard exercise plus a physical job Most people overestimate here. Three gym sessions a week is 1.375 to 1.55, not 1.725. Our example at 1.375 lands on roughly 1,940 kcal to maintain.
Once you know maintenance, the goal is a small shift, not a dramatic one: - To lose weight: subtract 300–500 kcal a day. That is roughly 0.25–0.5 kg (0.5–1 lb) a week — slow enough that you keep your energy, your training quality and most of your muscle. - To maintain: eat at your TDEE and let the daily numbers wobble. Weekly averages matter, single days do not. - To gain: add 250–500 kcal a day alongside resistance training, so more of the gain is muscle. Two floors worth respecting: going below roughly 1,500 kcal (men) or 1,200 kcal (women) makes it genuinely hard to hit your protein, fibre and micronutrient needs, and that is territory for a dietitian rather than a calculator.
Every equation is a population average applied to one person. Real metabolic rates vary by 10–15% either side of the prediction, so your calculated number is a starting point to test, not a fact about you. Track for two weeks. Weigh yourself a few mornings a week under the same conditions and take the weekly average — daily weight swings are mostly water, food in transit and salt, not fat. If the weekly average has not moved and you wanted it to, adjust by about 150–200 kcal and give it another fortnight. That loop — estimate, log, average, adjust — is the whole method. It is also why tracking beats guessing: without the log you have no data to adjust against.
Calories tell you about energy, and nothing else. Two 500-kcal meals can leave you full for four hours or hungry in forty minutes, depending on the protein and fibre in them. So use the calorie target as the outer boundary, then make the inside of it work: enough protein to hold onto muscle, enough fibre and volume to feel full, and food you actually want to eat again tomorrow. A target you can hold for six months beats an aggressive one you abandon in three weeks.
Put it into practice today
CoreFeed turns the logging into a daily quest — log a meal, feed your Anima, keep the streak.
Work out your numbers — freeAround a 1,000 kcal daily deficit, which is more than most people should attempt. A deficit that large is hard to sustain, tends to cost muscle as well as fat, and usually ends in a rebound. A 300–500 kcal deficit, giving 0.25–0.5 kg a week, is the range that people actually finish.
If you used an activity multiplier, exercise is already in your number — eating it back a second time double-counts it. Fitness trackers also tend to overestimate calories burned. If you train unusually hard on a given day, adding a portion back is reasonable; do it from hunger and performance, not from the watch.
Usually one of three things: portions have crept up since you last measured them, the deficit shrank because you now weigh less than when you did the maths, or you are looking at daily numbers instead of a weekly average. Re-run the calculation at your current weight and compare two full weeks before you change anything.
No. Your body settles up over weeks, not days. One larger day inside an otherwise consistent week barely moves the average. The habit that matters is coming back to the log the next day rather than abandoning it.