How to Lower Your BMI
Lowering BMI means losing body fat — specifically enough fat to shift your weight relative to your height. Here's what the evidence actually supports, how fast realistic progress happens, and what to ignore.
The Core Mechanic: Calorie Deficit
BMI falls when you lose weight. Weight falls when you consistently burn more calories than you consume — a calorie deficit. Everything else (low-carb, intermittent fasting, keto, exercise programmes) works only insofar as it helps you maintain a deficit.
A deficit of 500 kcal/day produces roughly 0.5 kg (1 lb) of fat loss per week. That's the well-validated rule of thumb from Wishnofsky (1958), supported by dozens of subsequent studies.
Calculate your maintenance calories (TDEE)
Your Total Daily Energy Expenditure is the number of calories that keeps your weight stable. Our dashboard calculates this using the Mifflin-St Jeor equation. Subtract 300–500 kcal from that number to create a moderate deficit.
Prioritise protein
Protein preserves muscle during weight loss, keeps you fuller for longer, and has a higher thermic effect than fat or carbs. Aim for 1.6–2.2 g per kg of body weight per day. This single change reduces hunger and protects lean mass better than any other dietary adjustment.
Reduce ultra-processed food
Ultra-processed foods are engineered to override satiety signals. A 2019 NIH randomised controlled trial (Hall et al.) found that people eating ultra-processed food consumed an average of 508 extra kcal/day compared to a whole-food diet — without noticing. Swapping them out reduces calorie intake without counting.
Add resistance training
Cardio burns calories during exercise. Resistance training raises your resting metabolic rate and preserves muscle during a deficit, meaning you burn slightly more calories 24 hours a day. Both matter; resistance training is underrated for body composition.
Improve sleep
Sleeping less than 7 hours increases ghrelin (hunger hormone) and decreases leptin (satiety hormone). A 2022 study found that people who extended sleep from 6.5 to 8.5 hours reduced calorie intake by ~270 kcal/day without any dietary instruction. Poor sleep makes deficits harder to maintain.
Realistic Timeline
| Height | Weight loss per BMI point | Time at 0.5 kg/week |
|---|---|---|
| 160 cm | 2.56 kg / 5.6 lbs | ~5 weeks |
| 170 cm | 2.89 kg / 6.4 lbs | ~6 weeks |
| 175 cm | 3.06 kg / 6.7 lbs | ~6 weeks |
| 180 cm | 3.24 kg / 7.1 lbs | ~6–7 weeks |
| 185 cm | 3.42 kg / 7.5 lbs | ~7 weeks |
This assumes 0.5 kg/week fat loss — a sustainable, well-evidenced rate. Faster loss is possible short-term but increases muscle loss and is harder to maintain.
What Doesn't Work (or Works Less Than Claimed)
- Detox teas / cleanses: No credible mechanism for fat loss. Any weight lost is water.
- Spot reduction: You cannot target fat loss in specific areas by exercising that area. Fat loss is systemic.
- Very low calorie diets (<800 kcal/day): Rapid short-term loss, but high muscle loss, metabolic adaptation, and near-universal rebound within 1–5 years without structured support.
- Specific "fat-burning" foods: Green tea, chilli, coffee — all have minor thermogenic effects (50–100 kcal/day at most). Not meaningless but not meaningful as a primary strategy.
Calculate your calorie target
Our dashboard shows your maintenance calories, fat-loss target, and muscle-gain target — calculated from your exact stats.
Open Health Dashboard →