How many calories should I eat to lose weight? The honest calculator

"How many calories should I eat to lose weight?" is the question every fat-loss search ends at, and the answer is almost never as clean as a single number. Your target depends on your body weight, sex, age, training load, and how aggressive you can stay without quitting in three weeks.

Here's the honest calculator, with the math, the worked examples, and the floor you shouldn't go under.

The quick answer

Most adults lose weight steadily on 1,500 to 2,200 kcal per day. The exact number depends on what your body burns at maintenance, which is your TDEE (Total Daily Energy Expenditure). Subtract 500 kcal from your TDEE and you'll lose roughly 0.5 kg / 1 lb per week.

Step 1: calculate your BMR

BMR (Basal Metabolic Rate) is what your body burns at complete rest. It's the calories you'd spend in 24 hours lying in bed, not moving. The most accurate formula for the general population is Mifflin-St Jeor (1990, American Journal of Clinical Nutrition):

Men: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5

Women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161

Worked examples:

• Woman, 30y, 165cm, 65kg: 650 + 1031 - 150 - 161 = 1,370 kcal BMR
• Man, 35y, 180cm, 80kg: 800 + 1125 - 175 + 5 = 1,755 kcal BMR

BMR alone is not what you should eat. It's the floor of your daily burn. Eat at BMR for weeks and your body adapts down: thyroid drops, training tanks, hunger climbs. BMR is just step one.

Step 2: multiply by your activity factor

This turns BMR into TDEE. The honest part of this step is that almost everyone overestimates their activity. "I work out three times a week" is rarely the same as "moderately active" if you sit for the rest of the day.

Take the woman from above (BMR 1,370). At sedentary (1.2) she burns 1,644 kcal/day. At lightly active (1.375) she burns 1,884 kcal/day. That's a 240 kcal gap based purely on which line she ticks. Pick the lower one if you're guessing. You can always adjust up after two weeks of data.

Step 3: subtract for the deficit

A pound of body fat stores roughly 3,500 kcal. So a 500 kcal daily deficit, sustained for 7 days, equals about 1 lb (0.45 kg) of fat loss per week. This is the evidence-backed default and the rate the CDC recommends as "gradual and steady" loss.

A 500 kcal cut works for most people without supervision. Anything larger needs you to either be very lean already (where slow is the only option) or very heavy (where a bigger deficit is metabolically tolerable for a while).

For the deeper version of why deeper isn't better, the full calorie deficit walkthrough covers metabolic adaptation, diet breaks, and why most aggressive cuts fail by week six.

Worked examples (the realistic version)

Example 1: Sedentary woman, 30y, 65kg, desk job

• BMR: 1,370 kcal
• Activity (sedentary, 1.2): TDEE = 1,644 kcal
• 500 kcal deficit: 1,144 kcal target

That's below the realistic floor for women (1,500 kcal). For her, the smarter move is to add steps and lift twice a week, push activity up to 1.375, and eat 1,400 kcal. Same fat loss, far more sustainable.

Example 2: Active woman, 30y, 65kg, runs and lifts

• BMR: 1,370 kcal
• Activity (very active, 1.725): TDEE = 2,363 kcal
• 500 kcal deficit: 1,863 kcal target

This works. She has room to fuel training and still create a meaningful gap. Most active women cutting weight should be eating closer to 1,800-2,000 kcal, not 1,200.

Example 3: Sedentary man, 35y, 180cm, 90kg

• BMR: 1,855 kcal
• Activity (sedentary, 1.2): TDEE = 2,226 kcal
• 500 kcal deficit: 1,726 kcal target

Workable but uncomfortable. Adding even light walking (1.375 multiplier) takes him to 2,550 kcal maintenance and a much easier 2,050 kcal cut.

Example 4: Active man, 30y, 80kg, lifts 4x/week

• BMR: 1,805 kcal
• Activity (moderate, 1.55): TDEE = 2,797 kcal
• 500 kcal deficit: 2,297 kcal target

Solid number. Eats well, trains hard, loses about 1 lb/week. This is the profile most fitness content writes for, but very few people are actually here.

The floors that matter

Not all deficits are safe. Below certain thresholds, the math stops working because your body adapts faster than you can lose fat.

If your TDEE is so low that a 500 kcal cut puts you under these floors, the answer is not to eat less. The answer is to raise TDEE: walk more, lift more, build more muscle, and eat at a smaller deficit from a higher maintenance.

How fast should the scale actually move?

Realistic loss rates by starting weight:

The first 1-2 weeks usually show 1-3 kg of "loss" that's almost entirely water and glycogen, not fat. Real fat loss settles in around week 3 and tracks closer to the table above. If the scale is dropping faster than that for more than a month, you're losing muscle alongside fat, which is the path to looking smaller but not leaner.

When to drop calories further (and when not to)

After 4-6 weeks at the same target, weight loss usually slows. This is metabolic adaptation, not the diet failing. Your TDEE drops as you weigh less and as your body becomes more energy-efficient. Two honest options:

Option 1: drop calories by 100-150 kcal. Small, sustainable, repeatable. Better than aggressive cuts.

Option 2: take a 1-2 week diet break at maintenance. Eat at your new (lower) TDEE. Hormones recover, the next deficit hits harder. This is the move most successful long-term cutters use.

The mistake to avoid: cutting another 300-500 kcal because progress slowed. That's how 1,800 kcal becomes 1,200 in three months and the whole thing collapses. The signal that the math is wrong is usually the logging, not the target. (We covered the most common reasons people stall in a deficit separately; logging errors top the list.)

After you hit your goal

Don't snap back to old eating. Reverse-dieting (slowly raising calories 50-100 kcal/week back toward maintenance) preserves the metabolic adaptation work. The full version is in maintenance calories after a diet. Most rebound weight gain happens in the four weeks immediately after "the diet ends," when calories jump 600+ kcal overnight.

The calories that hide

Even with a perfect target, deficits stall when intake is wrong. The four common leaks:

• Cooking fats. A tablespoon of olive oil is 120 kcal. A "splash" in the pan is rarely measured. Three meals a day cooked in oil is easily 300 kcal you didn't log.
• Drinks. A latte is 150-200 kcal. A glass of orange juice is 110. Two beers is 300. Liquid calories don't trigger fullness the way solid food does.
• Weekend portions. Five days at 1,800 kcal + two days at 2,800 kcal averages 2,085 kcal/day, well above the deficit target. The week-as-a-whole math is what matters.
• "Healthy" snacks. Almonds (170 kcal per 30 g handful), avocado toast (350 kcal), granola (450 kcal per 100 g). Calorie-dense doesn't mean unhealthy; it does mean countable.

For a forensic walkthrough of where calories sneak in, the four silent oatmeal add-ons is the same pattern applied to one breakfast.

The protein question

In a deficit, protein protects muscle. Eat too little and the weight you lose is partly lean tissue, which means you'll look softer at the same scale weight. The evidence-backed minimum during fat loss is 1.6 to 2.2 g per kg of body weight (Helms et al., 2014, ISSN review).

Hit that and the rest of the deficit can come from carbs and fat in whatever ratio fits your appetite. (The carbs vs fat in a deficit breakdown covers why the ratio matters less than people think, as long as protein and total calories are right.)

The verdict

The honest answer to "how many calories should I eat to lose weight" is: your TDEE minus 500, with a floor of 1,500 kcal for women and 1,800 kcal for men. For most adults that's somewhere between 1,500 and 2,200 kcal per day. Anything sharply lower is short-term theatre that almost always rebounds.

Calculate it once. Stay there for 3-4 weeks. Trust the trend, not the daily scale. Adjust by 100-150 kcal if progress stalls past 6 weeks, or take a maintenance break first. That's the entire system.

Pairs well with: the full calorie deficit walkthrough, why your deficit might not be working, and maintenance calories after a diet.