# Strength training and muscle during weight loss

When you lose weight, you lose more than fat. Strength training can help you keep muscle. The effect is real, but smaller than many promises suggest.[^1]

## How much is lost

According to one review, about 20 to 30% of the loss in people with overweight is fat-free mass.[^2] That is not the same as muscle, because it also includes water and organs. The popular one-quarter rule is considered in need of checking, as measurements are uncertain.[^3]

In an analysis of 20 studies, the share was 26.2% in programmes on food and movement and 17.5% with strength training added.[^1] For GLP-1 medicines, a review found a median of 28.3%, with a very wide spread. None of the studies measured what this means in daily life.[^4]

Less mass does not automatically mean less strength either: according to a review, strength usually holds during diet-based weight loss, and daily life often gets easier.[^2]

## What strength training does

A summary of 12 reviews reports 0.8 kg less loss of lean mass.[^5] In 114 studies with 4,184 people, lean mass was preserved on average with strength training and fewer calories.[^6] In absolute terms that is not much, and it was mostly observed over weeks.

The European Association for the Study of Obesity advises moderate to high intensity strength training to preserve lean mass.[^7] The German S3 guideline recommends it during weight loss too.[^8] It does not make weight loss faster, see [Movement and weight loss](https://kostenlos-abnehmen.de/en/wissen/bewegung).

## How much training

The WHO advises adults to do exercises for all major muscle groups on two or more days a week.[^9] The American College of Sports Medicine writes in 2026: any strength training is better than none, and few details decide. Strength rises from two sessions a week. This applies to healthy adults and was not studied in a calorie deficit.[^10]

There is no proven minimum for weight loss. An analysis of 65 studies found no clear effect of training volume.[^11] So start with what fits your week.

## And protein?

More protein helps a little on fewer calories: in 24 studies with 1,063 people, an average of 0.43 kg more fat-free mass was preserved.[^12] The DGE gives 0.8 g per kilogram of body weight for adults under 65 and 1.0 g as an estimate from 65. It names no separate value for weight loss.[^13] How to get there in daily life is under [Protein](https://kostenlos-abnehmen.de/en/wissen/eiweiss).

The EU approves these claims for foods that are at least a source of protein: “Protein contributes to a growth in muscle mass” and “Protein contributes to the maintenance of muscle mass”.[^14] That is no statement about weight loss.

## In older age

Muscle strength matters especially in older people. In a study of 160 people with obesity and 9% weight loss, lean mass fell by 5% with aerobic training, 2% with strength training and 3% with both. The combination improved physical performance most, and injuries occurred too.[^15]

The WHO advises people from 65 to do varied training with balance and strength on three or more days.[^9] Expert groups name 1.0 to 1.2 g of protein per kilogram for older adults, and with severe kidney disease this does not apply without medical advice.[^16]

## What nobody knows for sure

Studies showing that preserved lean mass prevents disease or falls during weight loss are missing. Whether muscle returns with regain is open: in 78 women, less lean mass came back per kilogram of fat than was lost.[^17] A review, on the other hand, found no loss after weight cycling in 18 studies.[^18]

If you have health conditions, pain or a long break behind you, talk to your doctor first. Good guidance helps at the start.

## Sources

[^1]: [Eisa N et al.: Lean Mass Changes With Incretin Therapy Versus Lifestyle Intervention. Diabetes Obes Metab, 2026](https://pubmed.ncbi.nlm.nih.gov/41877354/)
[^2]: [Cava E et al.: Preserving Healthy Muscle during Weight Loss. Adv Nutr, 2017](https://pubmed.ncbi.nlm.nih.gov/28507015/)
[^3]: [Heymsfield SB et al.: Weight loss composition is one-fourth fat-free mass. Obes Rev, 2014](https://pubmed.ncbi.nlm.nih.gov/24447775/)
[^4]: [Batsis JA et al.: Effect of Incretin-Based and Nonpharmacologic Weight Loss on Body Composition. Ann Intern Med, 2026](https://pubmed.ncbi.nlm.nih.gov/41996180/)
[^5]: [Bellicha A et al.: Effect of exercise training on weight loss, body composition changes, and weight maintenance. Obes Rev, 2021](https://pubmed.ncbi.nlm.nih.gov/33955140/)
[^6]: [Lopez P et al.: Resistance training effectiveness on body composition and body weight outcomes. Obes Rev, 2022](https://pubmed.ncbi.nlm.nih.gov/35191588/)
[^7]: [Oppert JM et al.: Exercise training in the management of overweight and obesity in adults. Obes Rev, 2021](https://pubmed.ncbi.nlm.nih.gov/34076949/)
[^8]: [German Obesity Society (DAG): S3 guideline on obesity, AWMF 050-001, version 5.0, 2024](https://register.awmf.org/assets/guidelines/050-001l_S3_Praevention-Therapie-Adipositas_2024-10.pdf)
[^9]: [Bull FC et al.: World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med, 2020](https://pubmed.ncbi.nlm.nih.gov/33239350/)
[^10]: [Currier BS et al.: ACSM Position Stand: Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults. Med Sci Sports Exerc, 2026](https://pubmed.ncbi.nlm.nih.gov/41843416/)
[^11]: [Lopez P et al.: Moderators of Resistance Training Effects in Overweight and Obese Adults. Med Sci Sports Exerc, 2022](https://pubmed.ncbi.nlm.nih.gov/35977113/)
[^12]: [Wycherley TP et al.: Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets. Am J Clin Nutr, 2012](https://pubmed.ncbi.nlm.nih.gov/23097268/)
[^13]: [German Nutrition Society (DGE): Reference values for protein](https://www.dge.de/wissenschaft/referenzwerte/protein/)
[^14]: [Regulation (EU) No 432/2012, Annex](https://eur-lex.europa.eu/legal-content/DE/TXT/HTML/?uri=CELEX:32012R0432)
[^15]: [Villareal DT et al.: Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults. N Engl J Med, 2017](https://pubmed.ncbi.nlm.nih.gov/28514618/)
[^16]: [Bauer J et al.: Evidence-based recommendations for optimal dietary protein intake in older people. J Am Med Dir Assoc, 2013](https://pubmed.ncbi.nlm.nih.gov/23867520/)
[^17]: [Beavers KM et al.: Is lost lean mass from intentional weight loss recovered during weight regain in postmenopausal women? Am J Clin Nutr, 2011](https://pubmed.ncbi.nlm.nih.gov/21795437/)
[^18]: [Sanaya N et al.: The Physiological Effects of Weight-Cycling. Curr Obes Rep, 2024](https://pubmed.ncbi.nlm.nih.gov/38172475/)

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Last updated: November 2026. This is general information and not medical advice.

Original article: https://kostenlos-abnehmen.de/en/wissen/krafttraining