How Many Calories Should You Eat to Lose Weight

How Many Calories Should You Eat to Lose Weight?

You've probably typed "how many calories should I eat to lose weight" into a search bar and gotten five different answers from five different websites. One app says 1,200. Another says 1,800. A friend swears by 1,500. None of them explain why the number is different for you.

Here's the truth: there's no single magic number. But there is a simple, repeatable method to find your number — and this guide walks you through it step by step, using the same math a dietitian would use in a clinic.

By the end, you'll know your personal calorie target, why crash diets backfire, and how to adjust your intake as your body changes.

What Determines How Many Calories You Need

Your calorie needs aren't guesswork. They're based on four measurable factors:

• Basal Metabolic Rate (BMR) — the energy your body burns just staying alive (breathing, circulating blood, repairing cells)
• Activity level — how much you move throughout the day, including workouts and daily tasks
• Body composition — muscle burns more calories at rest than fat does
• Age and sex — metabolism naturally slows with age, and men typically have a higher BMR than women due to more lean muscle mass

Weight loss happens when you consistently eat fewer calories than your body burns. This is called a calorie deficit, and it's the one non-negotiable principle behind every legitimate weight loss method — keto, intermittent fasting, calorie counting, or otherwise. They all work (when they work) because they create this deficit.

Step 1: Calculate Your Maintenance Calories

Before you can create a deficit, you need to know your maintenance calories — the number that keeps your current weight stable.

The most reliable starting point is the Mifflin-St Jeor equation, which nutrition professionals consider more accurate than older formulas like Harris-Benedict.

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161

Pro Tip

Weigh yourself in kilograms and measure height in centimeters for accuracy. If you only have pounds and inches, convert first — mixing units is the most common calculation mistake people make.

Step 2: Factor In Your Activity Level

Your BMR only accounts for calories burned at rest. Multiply it by an activity factor to get your Total Daily Energy Expenditure (TDEE):

This TDEE number is your maintenance calories — what you'd eat to stay at your current weight.

Step 3: Create Your Deficit

To lose weight, subtract calories from your TDEE. Here's where most guides get vague — so let's be specific.

• Losing 0.25 kg (0.5 lb) per week → subtract about 250 calories/day
• Losing 0.5 kg (1 lb) per week → subtract about 500 calories/day
• Losing 1 kg (2 lb) per week → subtract about 1,000 calories/day (only recommended for people with significant weight to lose, under medical guidance)

One kilogram of body fat holds roughly 7,700 calories, which is why a 500-calorie daily deficit produces about half a kilogram of loss per week.

Why Faster Isn't Better

A deficit larger than 1,000 calories/day, or eating below 1,200 calories (women) or 1,500 calories (men) without medical supervision, tends to backfire. Your body responds by:

1. Slowing your metabolism to conserve energy
2. Breaking down muscle tissue alongside fat
3. Increasing hunger hormones, making the diet unsustainable
4. Triggering rebound weight gain once normal eating resumes

A moderate deficit is slower, but it's the one you can actually stick to — and adherence is the real predictor of success, not the size of the deficit on day one.

Worked Example

Let's put this together for a real scenario.

Sarah, 34, is a woman who weighs 75 kg, is 165 cm tall, and works a desk job with three gym sessions a week.

• BMR = (10 × 75) + (6.25 × 165) − (5 × 34) − 161 = 1,489 calories
• Activity multiplier (lightly active) = 1,489 × 1.375 = 2,047 calories (maintenance/TDEE)
• Target for 0.5 kg/week loss = 2,047 − 500 = ~1,547 calories/day

That's Sarah's starting number. Not a generic 1,200 pulled from an app default.

Protein: The Variable Most Calculators Ignore

Most online calorie calculators tell you a total number and stop there. But how you fill that number matters as much as the number itself.

When you're in a calorie deficit, your body will pull energy from wherever is easiest — and without enough protein, a chunk of that comes from muscle, not fat. Losing muscle alongside fat is why some people end up "skinny fat": lighter on the scale, but with a similar or worse body composition than before.

Practical target: aim for 1.6–2.2 grams of protein per kilogram of body weight during a deficit. For Sarah at 75 kg, that's 120–165 grams of protein daily — spread across 3–4 meals so her body can actually use it for muscle repair.

The Unique Insight Most Articles Skip: Adaptive Thermogenesis

Here's something rarely explained clearly: your maintenance calories aren't fixed. As you lose weight, your TDEE drops too — partly because a smaller body burns fewer calories, and partly because of a phenomenon called adaptive thermogenesis, where your metabolism slows down more than body size alone would predict.

This is why the same 1,500-calorie diet that worked in month one stalls by month three. Your body has adapted.

What to do about it:

• Recalculate your TDEE every 4–6 weeks, or after every 5% of body weight lost
• Watch trends over 2–3 weeks, not single readings — daily weight fluctuates with water, sodium, and hormones
• If weight loss stalls for more than 2 weeks despite consistent tracking, reduce intake by another 100–150 calories rather than making a drastic cut
• Consider a "diet break" — one to two weeks at maintenance calories every 8–12 weeks — to help reset hunger hormones and reduce the intensity of adaptive thermogenesis. Research on periodic refeeding suggests this can improve long-term adherence, though results vary by individual.

Common Mistakes That Undermine a Calorie Deficit

• Not accounting for liquid calories — coffee add-ins, juice, and alcohol add up fast and are easy to forget when tracking
• Guessing portion sizes — studies consistently show people underestimate intake by 20–30% without measuring
• Ignoring recalculation — using the same target for six months as your weight (and TDEE) drops
• Cutting too aggressively out of impatience — leading to burnout, binge cycles, and quitting altogether
• Skipping strength training — a deficit without resistance exercise increases the share of weight lost that comes from muscle instead of fat

Your calorie target isn't a number you copy from an article — it's a calculation based on your body, your activity, and your goals, recalculated as you progress. Start with your TDEE, subtract a moderate deficit, prioritize protein, and adjust every few weeks instead of expecting one number to work forever.

Expert Tip: Track your intake for two weeks before changing anything. Most people don't have a calorie problem — they have an awareness problem. Once you can see what you're actually eating, adjusting it becomes far easier.