The problem with "just losing weight"
The scale doesn't tell you what you're losing. Aggressive dieting without the right inputs can result in losing 40–50% of your weight loss from muscle — not fat. This makes you look softer (not just smaller), lowers your metabolic rate, and makes weight regain more likely.
Body recomposition — losing fat while preserving (or gaining) muscle — is possible for most people. Here's how to do it.
1. Set a moderate calorie deficit
The golden zone for fat loss without significant muscle loss is a deficit of 300–500 kcal/day below your TDEE. This is roughly 0.3–0.5 kg/week of fat loss.
Larger deficits (600+ kcal/day) accelerate fat loss but significantly increase muscle protein breakdown, especially without adequate protein intake.
Calculate your TDEE with our Calorie Needs Calculator, then subtract 400 as a starting point. Not sure how many calories you need? See our full guide: How many calories should I eat per day?
2. Eat enough protein — more than you think
Protein is the single most important variable for preserving muscle in a deficit. The research is clear:
- Minimum: 1.6 g per kg of body weight per day
- Optimal (especially if training hard or in a large deficit): 2.0–2.4 g/kg
- Spread it across 3–4 meals — around 30–40g per sitting maximises muscle protein synthesis
For a 75 kg person, that's 120–180 g of protein per day. Chicken breast, Greek yoghurt, eggs, cottage cheese, lentils, and protein shakes are efficient sources.
3. Lift weights (or maintain resistance training)
Cardio burns calories but doesn't tell your body to keep muscle. Resistance training does. Studies consistently show that people who combine a calorie deficit with weight training lose significantly more fat and less muscle than those doing only cardio.
You don't need to train like a bodybuilder. 3 sessions per week of compound movements (squats, deadlifts, rows, presses) is enough to send the muscle-retention signal.
4. Prioritise sleep
This one is underrated. Sleep deprivation (under 6 hours) increases cortisol, reduces testosterone, and shifts the body toward muscle breakdown. One study found that people sleeping 5.5 hours per night lost 60% more lean mass and 55% less fat than those sleeping 8.5 hours — on identical calorie-restricted diets.
5. Track the right metrics
Stop relying on scale weight alone. Use a combination of:
- Body fat percentage — measure monthly. Our Body Fat Calculator uses the Navy method with just a tape measure. Not sure whether to track BMI or body fat? Read BMI vs Body Fat — which number actually matters?
- Progress photos — weekly, same lighting and pose
- Gym performance — if your lifts are holding steady or improving, you're keeping muscle
- Waist measurement — a shrinking waist is a reliable sign of fat loss regardless of what the scale says
Summary — the numbers
- Deficit: 300–500 kcal/day below TDEE
- Protein: 1.6–2.2 g per kg of body weight
- Training: 3+ resistance sessions/week
- Sleep: 7–9 hours/night
- Rate of loss: 0.3–0.5 kg/week (slower = better for muscle retention)
Consistency beats intensity. A moderate deficit sustained for 3–4 months will produce far better body composition results than an extreme diet held for 3 weeks.
For more context on your numbers before you start, read what is a healthy BMI and how many calories you should eat per day.