How Many Calories to Lose Weight? A Simple Method

To lose weight, eat fewer calories than your body uses each day. This is called a calorie deficit. A common starting point is 500 kcal below your total daily energy expenditure (TDEE). With that deficit, the estimated loss is about 0.45 kg (1 lb) a week. This guide shows how to find your number, with a worked example, and why progress sometimes stops.

This is general information, not medical advice. Talk to a doctor or dietitian before a large change in diet or training.

What a calorie deficit means

Your body uses energy all day. Breathing, moving, digesting food and exercise all use calories. Your TDEE is the total of these. If you eat less energy than your TDEE, your body uses stored energy, and your weight falls over time.

Body fat stores a lot of energy. A common rough rule is that about 7,700 kcal equals 1 kg of body fat. This is an approximation, not an exact value. Real weight change also includes water, salt and food in the gut, so the scale moves unevenly from day to day.

Step 1: Find your TDEE

TDEE comes from two numbers. First, estimate your basal metabolic rate (BMR) with a formula. Second, multiply it by an activity factor. The Mifflin-St Jeor formula is a common choice:

• Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
• Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161

The activity factor ranges from 1.2 (little movement) to 1.9 (very hard work or training twice a day). For a full table and more detail, read BMR vs TDEE explained.

Step 2: Choose a deficit

A deficit of 500 kcal a day is a common and moderate choice. Smaller deficits lose weight more slowly but are easier to keep. Many health agencies describe a loss of about 0.5 to 1 kg (1 to 2 lb) a week as a moderate pace.

Do not set a target that is far below your TDEE. Many nutrition guidelines advise against eating below about 1,200 kcal a day for women and 1,500 kcal a day for men without medical supervision.

Worked example: a woman

A woman is 30 years old, weighs 65 kg, is 165 cm tall and is lightly active. Her activity factor is 1.375.

1. BMR: 10 × 65 = 650, plus 6.25 × 165 = 1,031.25, minus 5 × 30 = 150, minus 161. Total: 1,370.25.
2. TDEE: 1,370.25 × 1.375 = 1,884.
3. Calorie target with a 500 kcal deficit: 1,884 − 500 = 1,384 kcal a day.
4. Weekly deficit: 500 × 7 = 3,500 kcal.
5. Estimated loss: 3,500 ÷ 7,700 = 0.45 kg a week.

Over 8 weeks, the estimate is 0.45 × 8 = about 3.6 kg. The table shows three deficit choices for the same person:

Each row uses the same TDEE of 1,884 kcal. A larger deficit gives a faster estimated loss, but a deficit of 750 kcal would set her target at 1,134 kcal, below the guideline above.

Worked example: a man

A man is 30 years old, weighs 80 kg, is 180 cm tall and is moderately active. His TDEE is about 2,759 kcal. With the same 500 kcal deficit, his target is 2,759 − 500 = 2,259 kcal a day. The estimated loss is again about 0.45 kg a week.

Why progress stalls

A plateau is common. Four causes explain most of them:

• Lower body weight. A lighter body uses less energy. For the woman above, after losing 3.6 kg her weight is 61.4 kg. Her BMR becomes 1,334 and her TDEE about 1,835 kcal, about 50 kcal less than before.
• Less movement. People often walk less after a diet starts. This is a quiet drop in daily energy use.
• Logging errors. Oil, sauces, snacks and weekend meals are often missed. One tablespoon of oil is about 120 kcal.
• Water and salt. Water changes can hide fat loss for a week or two.

Weigh yourself several times a week and use the weekly average. If the average does not move for two to three weeks, check your food log first. Then reduce the target by a small amount, or add daily steps.

How Metabolica does it

Metabolica calculates your BMR, TDEE and BMI from your age, height, weight and activity level. It offers three formulas: Mifflin-St Jeor, Harris-Benedict and Katch-McArdle. You can switch the formula at any time.

The personal setup asks a few questions about your goal, body, habits and sleep. It then shows a daily calorie target, macro targets, a water target and a goal date. The food log includes more than 100 everyday foods, so you can track calories, protein, carbs and fat against your target. Weekly calorie charts and a long-term weight trend show whether your plan works.

Metabolica gives estimates for general information. It is not a medical device and does not replace advice from a doctor or dietitian. Use its numbers as a starting point, then check them against your weight over several weeks.

For the full feature list, see the Metabolica app page. You can compare other tools on the apps page.

To calculate your own target, open Metabolica, enter your details and choose a deficit. For the protein, carb and fat split, read how to calculate macros next.

Frequently asked questions

How many calories should I eat to lose 1 kg a week?

A deficit of about 1,100 kcal a day gives about 1 kg a week, using the rough rule of 7,700 kcal per kg. For most people, a smaller and steadier deficit is easier to keep. Check the pace with your weekly average weight.

Is 1,200 calories a day enough to lose weight?

For most adult women, 1,200 kcal a day is a common lower guideline, and it is too low for many people. Do not go below it without advice from a doctor or dietitian. A smaller deficit from your TDEE is usually a better plan.

Why did I lose weight fast in the first week?

Most of the first-week loss is water and stored carbohydrate, not fat. Fat loss is slower and more even. Look at the trend over several weeks.

How long should I stay in a calorie deficit?

There is no fixed length. Many people take breaks at maintenance calories after several weeks of deficit. Review your progress every few weeks and adjust your plan.