1. The One Principle That Drives All Weight Loss
Weight loss comes down to one thing: energy balance. If you consume fewer calories than your body burns, it burns stored fat to make up the difference. This is called a calorie deficit.
1 kg of body fat stores approximately 7,700 calories. So to lose 1 kg of fat, you need a total deficit of 7,700 calories. At a 500 calorie/day deficit, that takes about 15 days — or roughly 0.5 kg per week.
This is not a diet. It is physics. The variables are your TDEE (total calories burned per day) and your intake.
2. Step 1 — Calculate Your BMR
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep your heart beating, lungs breathing, and organs functioning. The most accurate common formula is the Mifflin-St Jeor equation:
For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
For women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Example: 30-year-old woman, 60 kg, 165 cm:
- BMR = (10 × 60) + (6.25 × 165) − (5 × 30) − 161
- BMR = 600 + 1031.25 − 150 − 161 = 1,320 calories/day
3. Step 2 — Multiply by Your Activity Level to Get TDEE
TDEE (Total Daily Energy Expenditure) = BMR × activity multiplier. This is the total calories you burn each day including exercise and movement:
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little or no exercise | × 1.2 |
| Lightly active | Light exercise 1–3 days/week | × 1.375 |
| Moderately active | Moderate exercise 3–5 days/week | × 1.55 |
| Very active | Hard exercise 6–7 days/week | × 1.725 |
| Extra active | Physical job + hard daily exercise | × 1.9 |
Continuing the example (lightly active): TDEE = 1,320 × 1.375 = 1,815 calories/day. This is her maintenance level.
🔥 Calorie Calculator
Enter your age, weight, height, and activity level to calculate your TDEE and recommended calories for weight loss, maintenance, or muscle gain.
Calculate My TDEE →4. Step 3 — Set Your Calorie Deficit
Subtract calories from your TDEE to create a deficit. Here is what different deficit sizes produce:
| Daily Deficit | Weekly Fat Loss | Sustainability |
|---|---|---|
| 200–300 cal | ~0.2 kg/week | Very easy, minimal hunger |
| 300–500 cal | ~0.3–0.5 kg/week | Recommended for most people |
| 500–750 cal | ~0.5–0.75 kg/week | Moderate — requires planning |
| 750–1,000 cal | ~0.75–1 kg/week | Aggressive — monitor closely |
| >1,000 cal | >1 kg/week | Not recommended — muscle loss risk |
For our example (TDEE 1,815 cal/day), a 400 calorie deficit means eating 1,415 calories/day to lose approximately 0.4 kg per week.
5. Why "Eat Less, Move More" Often Fails
Most people know the principle. Why doesn't it work? These are the most common reasons:
- Underestimating food intake — Studies show people underestimate how much they eat by 30–50%. Cooking oils, sauces, and snacks add up silently.
- Overestimating exercise burn — A 30-minute walk burns ~150 calories. A gym session burns 300–400. These are smaller numbers than most fitness trackers suggest.
- Metabolic adaptation — After weeks of restriction, your body reduces TDEE by slowing non-essential processes. This is why weight loss stalls after 4–8 weeks.
- Eating too little — Very low calorie diets (below 1,200 cal for women, 1,500 for men) trigger muscle breakdown and suppress metabolism long-term.
- Weekend offset — Eating at a deficit Mon–Fri and overeating on weekends can completely wipe out the week's deficit.
6. BMI Check: Are You in a Healthy Range?
Before aggressive calorie cutting, check if your current BMI places you in the overweight or obese range — or if you are already near healthy weight, in which case a smaller deficit and focus on body composition (muscle gain) is more appropriate.
⚖ BMI Calculator
Check your Body Mass Index and see how your weight compares to the healthy range for your height.
Check My BMI →7. Practical Tips That Actually Work
- Weigh food for 2 weeks — Just once, to calibrate your portion intuition. Especially for oils, nuts, rice, and chapati.
- Prioritise protein — 1.2–1.6g per kg of body weight per day. Protein is the most filling macronutrient and protects muscle during a deficit.
- Eat whole foods — Whole grains, vegetables, and legumes are filling per calorie. Ultra-processed foods are calorie-dense but not filling.
- Don't drink calories — Juices, chai with sugar, soft drinks, and alcohol add 200–400 calories with no satiety benefit.
- Take diet breaks — Every 8–12 weeks, return to maintenance calories for 1–2 weeks. This resets hormones and prevents metabolic adaptation.