What a calorie deficit is
Your body uses energy all day: to breathe, think, digest and move. That total is your TDEE (total daily energy expenditure). If you eat less than your TDEE, your body covers the gap from stored energy, mostly fat, and your weight goes down over time. That gap is the calorie deficit.
Step 1: find your maintenance calories
Start with your basal metabolic rate (BMR) from the Mifflin–St Jeor equation, then multiply it by an activity factor:
- BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 (men) or − 161 (women)
- TDEE = BMR × activity (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active)
Our free calorie calculator does this for you and suggests a protein goal.
Step 2: choose a deficit you can keep
| Daily deficit | Typical pace | Who it suits |
|---|---|---|
| 250 kcal | about 0.25 kg (0.5 lb) a week | Close to your goal, or you want it to feel easy |
| 500 kcal | about 0.5 kg (1 lb) a week | Most people starting out |
| 750+ kcal | faster, harder to sustain | Only with professional advice |
Do not go below about 1,200 kcal a day for women or 1,500 kcal for men without medical supervision. Very low intakes make it hard to get enough protein and nutrients and often end in rebound eating.
Step 3: track, then adjust
Calculators give a starting point, not the truth. Real needs differ by a few hundred calories. Log what you eat for two or three weeks and watch your weight trend, not daily jumps. If the trend is flat, lower the target by 100–200 kcal; if you are losing faster than planned and feel drained, raise it. Stuck for weeks? See why you might not be losing weight in a deficit.
How to make a deficit easier
- Protein at every meal. Around 1.6 g per kg of body weight a day keeps you fuller and protects muscle.
- Volume foods: vegetables, soups, fruit and lean protein fill the plate for fewer calories.
- Watch liquid calories: juice, sweet coffee drinks and alcohol add up quickly.
- Make logging fast. A photo, a barcode scan or a few words is enough; the habit matters more than perfect numbers.
- Plan, don’t restrict. A meal plan that already fits your calories removes daily decisions.
This guide is general information for healthy adults, not medical advice. If you are pregnant, breastfeeding, under 18 or have a medical condition, talk to a doctor first.