Losing Weight Is One Thing, Preserving Muscle Is Another, Researchers Warn - Video

Is cutting calories enough to lose weight, or does preserving muscle matter just as much? A new position paper suggests that sustainable weight loss depends not only on maintaining a calorie deficit but also on adequate protein intake, resistance training and personalised dietary strategies.

Published in the Journal of the International Society of Sports Nutrition, the position paper from the International Society of Sports Nutrition (ISSN) outlines evidence-based recommendations for reducing body weight and fat mass while preserving lean muscle and metabolic health.

Researchers reviewed scientific evidence including systematic reviews, meta-analyses and randomized controlled trials examining different dietary approaches.

The findings emphasised that a sustained calorie deficit remains the primary driver of weight loss, regardless of whether individuals follow low-fat, low-carbohydrate, ketogenic or intermittent fasting diets.

Although very-low-calorie diets may produce faster initial weight loss, they do not consistently provide superior long-term outcomes and may increase the risk of nutritional deficiencies, muscle loss and fatigue.

The paper highlighted the importance of adequate protein consumption, recommending approximately 1.2 to 1.6 grams per kilogram of body weight daily for physically active individuals. Higher intakes of 1.6 to 2.2 grams per kilogram may help preserve or build muscle when combined with resistance training.

For lean, resistance-trained individuals undergoing calorie restriction, higher protein intakes may be beneficial for maintaining lean mass.

Importantly, intermittent fasting and time-restricted eating were not consistently more effective than continuous calorie restriction when overall energy intake was comparable.

Similarly, low-fat and ketogenic diets generally produced comparable weight-loss outcomes when calories and protein were matched, although ketogenic diets may increase LDL cholesterol in some individuals.

Researchers also noted that weight loss can trigger metabolic adaptations, including reduced energy expenditure and increased hunger, making long-term weight maintenance challenging.

The position paper recommends monitoring body composition rather than relying exclusively on scale weight, alongside regular strength training, meal planning and professional dietary guidance.

REFERENCE: Aragon, A. A., Campbell, B. I., Schoenfeld, B. J. et al. (2026). International Society of Sports Nutrition position stand: diets for body weight reduction. Journal of the International Society of Sports Nutrition, 23(1). DOI: 10.1080/15502783.2026.2740266