In 30 seconds
- Lose between 0.5 and 1% of your body weight a week. In athletes, going more slowly preserved muscle better.
- Increase your protein: in a calorie deficit, 2.3-3.1 g per kilo of lean mass is recommended, about 1.8-2.5 g per kilo of body weight.
- Keep up your strength training and sleep well: on the same diet, sleeping 5.5 hours instead of 8.5 meant losing less than half as much fat and more lean mass.
- Supplements are the last piece: protein and creatine, with their official claims, and CLA and L-carnitine, with their figures from the studies.
Getting leaner is not just about losing weight: it is about losing fat without sacrificing the muscle you have worked so hard for. This guide summarises what the studies say, in order of importance.
What really works
- A moderate deficit that brings your weight down by between 0.5 and 1% a week.
- High protein, more than when you are not in a deficit.
- Strength training, to give your body a reason to hold on to muscle.
- Good sleep, which has more influence than it seems on what you lose: fat or muscle.
- Supplements, at the end of the list, as support for everything above.
Elite athletes
Losing slowly or quickly: what happened to muscle
How much to lose a week
The key review on natural bodybuilding contest preparation recommends losing between 0.5 and 1% of your body weight a week to preserve as much muscle as possible 1:
| Your weight | 0.5% a week | 1% a week |
|---|---|---|
| 60 kg | 0.3 kg | 0.6 kg |
| 70 kg | 0.35 kg | 0.7 kg |
| 80 kg | 0.4 kg | 0.8 kg |
| 90 kg | 0.45 kg | 0.9 kg |
| 100 kg | 0.5 kg | 1 kg |
Rate recommended by Helms et al., 2014. Look at the average of several mornings, not a single day.
Going more slowly pays off. In a study with elite athletes, one group lost 0.7% a week by eating 19% less, and another lost 1% by eating 30% less. Both lost the same amount of weight, but the slow group gained 2.1% lean mass and lost more fat; the fast group did not gain lean mass 2.
In practice: start with a moderate cut and weigh yourself several mornings a week. If the average does not go down, adjust a little; if it falls by more than 1%, eat a little more.
Protein in a fat-loss phase
How much protein a day per kilo of body weight
Protein: more than usual
When you eat less, your body is more inclined to use muscle. That is why protein goes up in a fat-loss phase: 2.3-3.1 g per kilo of lean mass a day is recommended 1. For most people, that is about 1.8-2.5 g per kilo of body weight:
| Your weight | 1.8 g per kilo | 2.4 g per kilo |
|---|---|---|
| 60 kg | 108 g | 144 g |
| 70 kg | 126 g | 168 g |
| 80 kg | 144 g | 192 g |
| 90 kg | 162 g | 216 g |
Equivalent to 2.3-3.1 g per kilo of lean mass at 20% body fat (Helms et al., 2014).
In a 4-week trial with a large deficit and intense training, the group that had 2.4 g of protein per kilo gained lean mass and lost more fat than the group that had 1.2 g 3.
Spread it over 3-6 meals, with about 0.4-0.5 g per kilo before and after training 1. If you find it hard to reach your target with food, a protein shake is the simplest way. Protein contributes to the maintenance of muscle mass 5. A varied and balanced diet and a healthy lifestyle are important.
Do not drop strength training
The deficit is what makes you lose fat; strength training is what tells your body that muscle is needed. Keep your main exercises and the intensity, even if you have to reduce the volume a little.
Cardio is a tool to help balance the deficit, not a substitute for strength training. In the study with elite athletes, the group that lost weight slowly and kept up strength training improved its maximal strength 2.
Little sleep on a diet
Same diet, 5.5 hours in bed instead of 8.5
Sleep decides what you lose
It is the most overlooked factor. In one trial, 10 adults with overweight followed the same diet twice for two weeks: once sleeping 8.5 hours and once sleeping 5.5 hours 4.
| 8.5 hours in bed | 5.5 hours in bed | |
|---|---|---|
| Fat lost | 1.4 kg | 0.6 kg |
| Lean mass lost | 1.5 kg | 2.4 kg |
Source: Nedeltcheva et al., 2010. 10 adults with overweight, the same deficit in both phases.
They lost almost the same weight, but with little sleep they lost 55% less fat and 60% more lean mass, and they were hungrier 4. If you are in a fat-loss phase, sleep is part of the plan.
Supplements: the last piece
The Helms review considers creatine, caffeine and beta-alanine useful during contest preparation; for the rest, research is ongoing 1. This is what is known about each one:
- Creatine: “Creatine increases physical performance in successive bursts of short-term, high intensity exercise.” The beneficial effect is obtained with a daily intake of 3 g of creatine 5. If you are unsure whether to take it now, read creatine while cutting.
- Protein: to reach your daily figure without eating more volume. Protein contributes to the maintenance of muscle mass 5.
- CLA and L-carnitine: these are two classics of fat-loss phases. In meta-analyses, CLA was associated with about 0.09 kg less fat per week compared with placebo, and L-carnitine with 1.33 kg more weight loss. We summarise them with their figures in CLA: what the studies say and L-carnitine: what the studies say. If you are looking for a fat burner, they are the stimulant-free option: we compare them with the rest in fat burners: which ones work.
Supplements add to that foundation: a well-planned deficit, enough protein and enough sleep. With those in place, you can weigh up which ones suit you.
Common mistakes
- Cutting back too much: faster is not better; it usually costs muscle and strength.
- Falling short on protein: just when you need it most.
- Swapping strength training for cardio alone: you lose the signal to preserve muscle.
- Sleeping too little: more hunger and more muscle lost.
- Looking at the scales on a single day: weight goes up and down with water and food. Focus on the weekly average.
Frequently asked questions
How much weight should I lose a week in a fat-loss phase?
Between 0.5 and 1% of your body weight. If you weigh 80 kg, between 0.4 and 0.8 kg a week. In elite athletes, losing weight at a slower rate preserved muscle and strength better.
How much protein do I need so I do not lose muscle?
In a calorie deficit, 2.3-3.1 g per kilo of lean mass is recommended, which for most people is about 1.8-2.5 g per kilo of body weight. Spread it over 3-6 meals, with about 0.4-0.5 g per kilo before and after training.
Is cardio or strength training better for getting lean?
What makes you lose fat is the deficit. Strength training is what helps you keep your muscle in the meantime. The ideal is to keep up your strength training and add whatever cardio helps you balance the deficit.
Which supplements help with fat loss?
“Protein contributes to the maintenance of muscle mass.” “Creatine increases physical performance in successive bursts of short-term, high intensity exercise.” The beneficial effect is obtained with a daily intake of 3 g of creatine. CLA and L-carnitine are two classics of fat-loss phases: in meta-analyses, about 0.09 kg less fat per week with CLA and 1.33 kg more weight loss with L-carnitine, compared with placebo.
How long should a fat-loss phase last?
It depends on how much fat you want to lose. At a rate of 0.5-1% a week, losing 5 kg takes between 7 and 14 weeks if you weigh 75 kg. Going faster usually comes at a cost in muscle.
Sources
- Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. J Int Soc Sports Nutr. 2014;11:20. View publication
- Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. View publication
- Longland TM, Oikawa SY, Mitchell CJ, Devries MC, Phillips SM. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. Am J Clin Nutr. 2016;103(3):738-746. View publication
- Nedeltcheva AV, Kilkus JM, Imperial J, Schoeller DA, Penev PD. Insufficient sleep undermines dietary efforts to reduce adiposity. Ann Intern Med. 2010;153(7):435-441. View publication
- Commission Regulation (EU) No 432/2012 establishing a list of permitted health claims made on foods. View publication
Information based on published studies. It does not replace the advice of a doctor or registered dietitian. The results describe what was measured in each study, not the properties of any specific product.
