Trying to lose weight and unsure which type of workout to add to your weekly routine? A new study from the School of Public Health and the Sylvan Adams Sport Science Institute at Tel Aviv University points to a clear conclusion: Strength training, also known as resistance training, is the most effective tool for achieving "high-quality" weight loss that reduces fat while preserving and even increasing muscle mass.
The study was led by Prof. Yftach Gepner, along with Yair Lahav and Roi Yavetz, and was published in the scientific journal Frontiers in Endocrinology. Researchers analyzed data from hundreds of women and men aged 20 to 75 who participated in a structured weight loss program.
All participants followed a low-calorie diet with a controlled energy deficit. They were divided into three groups based on their personal choice: no exercise, aerobic exercise, or strength training.
The findings show that overall weight loss was similar across all groups, but the key difference was in body composition. Participants who performed strength training lost more fat than those in any other group and were the only ones to preserve and even increase muscle mass.
In contrast, participants who did not exercise, as well as those who relied solely on aerobic activity, lost a substantial portion of their muscle mass during the weight loss process.
The research team explained that while total weight loss numbers were comparable, the quality and composition of the weight loss varied sharply. Weight loss without strength training, including programs based only on aerobic exercise, was accompanied by muscle loss. Strength training, however, led to weight loss driven primarily by fat reduction while maintaining or increasing muscle mass. This, the researchers said, results in a healthier, more stable and more effective long-term outcome.
Muscle mass plays a central role in overall health and metabolism. Muscle accounts for about 40% of body weight and is responsible for a significant portion of daily energy expenditure, even at rest. When muscle mass declines, metabolic rate slows, weight loss becomes more difficult and the risk of regaining weight after dieting increases. As a result, weight loss that does not preserve muscle may be less stable and potentially harmful over time.
Beyond metabolism, maintaining muscle mass is essential for daily function, strength, stability and balance. Muscle loss can impair physical ability, increase the risk of injuries and falls and accelerate sarcopenia, the age-related gradual loss of muscle mass. This process can occur even in relatively young people during poorly balanced dieting.
The study also found a clear advantage for strength training in reducing waist circumference, a key indicator of abdominal obesity and cardiometabolic risk. The greatest reductions in waist size were seen among strength training participants and were strongly linked to fat loss, highlighting the benefits for heart and metabolic health.
According to the researchers, the findings underscore that not all weight loss is equal. High-quality weight loss reduces fat, preserves muscle and supports long-term health and weight maintenance. The conclusion is clear: Incorporating strength training into weight loss programs is a vital component of healthy, effective and sustainable weight loss for both women and men.
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Research team (from left): Yair Lahav, Roi Yavetz and Prof. Yftach Gepner
(Photo: Tel Aviv University)
Summing up the findings, Prof. Gepner said weight loss should not be measured solely by the number of kilograms lost but by its quality. When proper nutrition is combined with strength training, fat can be reduced efficiently while preserving and even improving muscle mass, a critical factor for metabolic health, daily functioning and long-term weight control.
Resistance training, he added, is not just for athletes but an essential tool for anyone seeking healthy, safe and sustainable weight loss.