How to improve body composition
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How to improve body composition

As seen previously, improving body composition can confer a competitive advantage to some athletes. Hence the interest of athletes and coaches on how to improve body composition.

In general, improving body composition means decreasing fat mass and increasing fat-free mass or muscle mass (a.k.a. lean body mass). Besides training protocols and periodisation, there are nutrition approaches that can achieve a favourable change.

How to improve body composition

Body composition can be improved using a variety of nutrition approaches. Broadly speaking, they can be categorised as dietary manipulation (e.g. tweaking energy intake or macronutrient levels) and supplementation.

Note that not all research in this area is done on athletes. Some studies use trained individuals (e.g. recreational exercisers), some use subjects from the general population. As it happens with skill development, the closer one is to the goal, the harder it is to make gains.

Dietary manipulation

Low energy

Low-energy diets and very-low-energy diets can work for weight loss, however they should be combined with resistance exercise and higher than usually recommended protein intakes (1.2-1.5 g/kg/day). Low-energy is usually defined as 800-1200 kcals (3347-5021 kJ) per day and very-low-energy as 400-800 kcals (1674-3347 kJ) per day. Very low energy levels are often achieved through liquid supplements (1). Due to the demands of training and competition, low-energy and very-low-energy diets are not advisable for athletes.

Low fat

Low fat diets, defined as those containing 20-35% of energy from fat, may have a small effect on improving body composition. Very-low-fat diets (i.e. 20% of energy from fat) don’t seem to have any advantage over diets containing ~40% of energy from fat (1). Moreover, given that some fats are essential components of healthy diets and important for the absorption of certain nutrients, it might not be the best idea to aim for extremely low levels of dietary fats.

Low carb

Given that the recommended carbohydrate intake is usually 45-65% of daily energy intake as per government recommendations, low-carbohydrate diets are hard to define. “Very-low-carbohydrate diets” (about 50 grams per day) seem to be effective for fat loss as they have shown to decrease more fat mass than control diets (1).

Ketogenic diets, in which carbohydrate intake is normally under 50 grams per day, are not defined by their macronutrient composition, but for their ability to elevate ketone production on the body. Ketogenic diets may help improve body composition and increase fat oxidation capacity (i.e. ability to burn fat instead of carbs for fuel). However, these diets tend to compromise aerobic performance (2). This approach can be effective when combined with resistance training in reducing total and visceral fat, although not in inducing hypertrophy (i.e. muscle growth) (3).

Intermittent fasting

Time restricted feeding (also known as intermittent fasting or 16:8) has shown to reduce body fat and maintain fat-free mass, leading to improved body composition. However, it can also reduce testosterone and insulin growth factor 1 (IGF-1) levels (4), which could be beneficial from a longevity point of view but not necessarily from an athletic perspective.


Protein supplements are commonly taken to improve body composition, in particular to stimulate muscle tissue synthesis. However, protein quality is important. When combined with resistance exercise, both beef and whey protein have been shown to have a better effect on muscle mass than other protein sources. Moreover, whey is easier to digest and has a greater essential amino acid content (5).

A collagen peptide supplement (15 g per day of type I collagen) combined with resistance exercise has been shown to be more effective than exercise alone in improving body composition in older individuals with sarcopenia (reduced muscle mass) (6).

On the topic of supplements, literature review found arguments for and against a combination of creatine monohydrate and beta-hydroxy beta-methylbutyrate (HMB) could improve body composition more than either supplement alone. This can be explained by the ability of creatine monohydrate to increase muscle mass and the ability of HMB to enhance fat oxidation (7).

Summary and recommendations

A better body composition does not always guarantee improved athletic performance. Having said that, athletes looking to improve body composition can use a variety of dietary and supplement approaches. The right strategy for each athlete will depend on several factors including their current diet, genetic makeup and existing health conditions. Please consult a sports dietitian before implementing changes to your diet.


  1. Aragon AA, Schoenfeld BJ, Wildman R, Kleiner S, VanDusseldorp T, Taylor L, et al. International society of sports nutrition position stand: diets and body composition. J Int Soc Sports Nutr [Internet]. 2017;14. Available from:
  2. Zinn C, Wood M, Williden M, Chatterton S, Maunder E. Ketogenic diet benefits body composition and well-being but not performance in a pilot case study of New Zealand endurance athletes. J Int Soc Sports Nutr [Internet]. 2017;14. Available from:
  3. Vargas S, Romance R, Petro JL, Bonilla DA, Galancho I, Espinar S, et al. Efficacy of ketogenic diet on body composition during resistance training in trained men: a randomized controlled trial. J Int Soc Sports Nutr [Internet]. 2018;15(1):31. Available from:
  4. Moro T, Tinsley G, Bianco A, Marcolin G, Pacelli QF, Battaglia G, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. J Transl Med [Internet]. 2016;14(1):290. Available from:
  5. Valenzuela PL, Mata F, Morales JS, Castillo-García A, Lucia A. Does Beef Protein Supplementation Improve Body Composition and Exercise Performance? A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2019/06/28. 2019;11(6).
  6. Zdzieblik D, Oesser S, Baumstark MW, Gollhofer A, König D. Collagen peptide supplementation in combination with resistance training improves body composition and increases muscle strength in elderly sarcopenic men: a randomised controlled trial. Br J Nutr. 2015;114(8):1237–45.
  7. Fernández-Landa J, Calleja-González J, León-Guereño P, Caballero-García A, Córdova A, Mielgo-Ayuso J. Effect of the Combination of Creatine Monohydrate Plus HMB Supplementation on Sports Performance, Body Composition, Markers of Muscle Damage and Hormone Status: A Systematic Review. Nutrients. 2019/10/23. 2019;11(10).

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