How Many Calories Should I Eat to Lose Weight?
Work out your maintenance calories, pick a deficit you can keep, set your protein, and adjust after three weeks. With worked examples.
To lose weight, eat a little less than your maintenance calories: the amount that keeps your weight the same. For most people a deficit of 300 to 500 calories a day is enough to lose fat steadily without constant hunger. Find your maintenance with the Mifflin–St Jeor equation (or our free calorie calculator), subtract your deficit, and check your weight trend after two to three weeks.
The rest of this guide shows how to do each step, with worked examples, and what to do when the scale stops moving.
Step 1: Find your maintenance calories
Your body burns energy in three ways: keeping you alive at rest (your basal metabolic rate, or BMR), moving around during the day, and digesting food. Added together, that is your total daily energy expenditure (TDEE). Eat about your TDEE and your weight stays roughly flat.
The most widely used formula for BMR is Mifflin–St Jeor:
- Women: 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161
- Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5
Then multiply BMR by an activity factor:
| Activity | Factor |
|---|---|
| Sedentary (desk job, little exercise) | 1.2 |
| Lightly active (exercise 1–3 days a week) | 1.375 |
| Moderately active (3–5 days a week) | 1.55 |
| Very active (hard exercise 6–7 days a week) | 1.725 |
Worked example (illustrative): a 35-year-old woman, 165 cm, 75 kg, who walks most days and does two workouts a week.
- BMR = 750 + 1,031 − 175 − 161 = 1,445 kcal
- Lightly active: 1,445 × 1.375 = about 1,990 kcal a day to maintain
Be honest with the activity level. Most people overestimate it, and picking "moderately active" when you sit all day can add 300 calories that don't exist.
Step 2: Choose a deficit you can actually keep
A pound of body fat holds roughly 3,500 calories, so a 500-calorie daily deficit is often quoted as "a pound a week". Treat that as a rough guide: real weight loss is less tidy, especially after the first few weeks.
The bigger the deficit, the faster you lose weight, and the harder it is to stick to. Very low intakes tend to bring hunger, low energy, poor workouts and more muscle loss. A practical way to choose:
- 300 calories below maintenance: gentle and easy to sustain. This is the default the Thrive Fit app uses.
- 500 calories below maintenance: faster, still manageable for most people with some planning.
- More than 750 below: hard to keep up and rarely worth it without medical supervision.
Whatever the math says, most women shouldn't go below about 1,200 calories a day, and most men below about 1,500, unless a doctor is supervising.
For our example, 1,990 − 300 = about 1,690 kcal a day, or 1,490 kcal for the faster option.
Step 3: Set your protein first
When you eat less, your body can break down muscle as well as fat. Protein, together with strength training, protects muscle, and it keeps you fuller than the same calories from carbs or fat.
A good target while losing weight is 1.6 to 2.2 g of protein per kg of body weight. The Thrive Fit app uses 1.8 g/kg. For our 75 kg example, that's about 135 g of protein a day: roughly 35 g at each of three meals plus a high-protein snack.
Simple ways to hit it:
- Start every meal with a palm-sized portion of protein: chicken, fish, eggs, tofu, Greek yogurt, lentils.
- Swap one snack for something protein-rich, like cottage cheese or a protein shake.
- Use a plan that does the work. The High-Protein meal plan and Weight Loss meal plan list the protein in every meal.
After protein, split the rest of your calories between carbs and fat in a way you enjoy. Around a quarter to a third of calories from fat works for most people.
Step 4: Track for two to three weeks
A calorie target only works if you know roughly what you're eating. You don't need to weigh every grape forever, but a few weeks of honest tracking teaches you what portions look like.
- Log everything, including oils, sauces and drinks. These are the most common hidden calories.
- If typing in food is what makes you quit, use a photo. The Thrive Fit calorie counter estimates calories and macros from a picture of your plate.
- Weigh yourself at the same time each morning, after the bathroom and before eating.
Step 5: Adjust using your weekly average
Daily weight jumps around by 1–2 kg with water, salt, carbs and hormones. Ignore single readings and compare weekly averages.
| What you see after 3 weeks | What to do |
|---|---|
| Losing about 0.25–1% of body weight a week | Keep going, nothing to change |
| No change in the weekly average | Lower intake by 100–200 kcal, or add a daily walk |
| Losing faster than 1% a week and feeling drained | Eat 100–200 kcal more |
Make one change at a time and give it two weeks before judging.
Why the scale stops moving
It's normal for weight loss to slow down. As you get lighter, your maintenance calories drop, so the same intake becomes a smaller deficit. People also tend to move less without noticing when they eat less. Recalculate your numbers after every 4–5 kg lost, and keep your daily steps up.
If you've been in a deficit for several months, a week or two eating at maintenance can make the next phase easier to stick to. It doesn't "reset your metabolism", but it gives you a mental break.
Exercise: helpful, not required
You can lose weight through food alone, but exercise changes what you lose. Strength training two to four times a week helps you keep muscle, so the weight that comes off is mostly fat. You don't need a gym: a beginner home workout plan with bodyweight moves is enough to start.
FAQ
How many calories should a woman eat to lose weight?
It depends on her size, age and activity. Many women lose weight at 1,400 to 1,900 calories a day, but calculate your own maintenance and subtract 300–500. Avoid going below about 1,200 calories without medical advice.
Is a 1,200-calorie diet safe?
For some smaller, less active women it can be, but it's very low for most people and hard to get enough protein and nutrients. Use it only with guidance from a doctor or dietitian.
Do I need to count calories forever?
No. A few weeks of tracking teaches you portion sizes. Many people then track occasionally, or only when progress stalls.
Should I eat back the calories I burn exercising?
Usually not all of them. Activity trackers often overestimate calories burned. Set your activity level in your maintenance estimate instead, and adjust based on your weekly weight trend.
