A new Israeli study shows that not all weight loss is created equal, and that strength training offers unique benefits for both men and women, according to TPS-IL. Scientists found that while different exercise strategies can lead to similar reductions on the scale, resistance training delivers superior results by reducing fat while preserving — and in some cases increasing — muscle mass, Tel Aviv University announced.

The study, conducted at the Gray Faculty of Medical and Health Sciences and the Sylvan Adams Sports Science Institute, was led by Prof. Yftach Gepner, together with Yair Lahav and Roi Yavetz. The team analyzed data from hundreds of adults aged 20 to 75 who participated in a structured weight-loss program. All participants followed a low-calorie diet, but they were divided into three groups: no physical exercise, aerobic exercise, or resistance training.

The researchers found that while total weight loss was similar across all groups, the composition of that loss differed significantly. Those who performed strength training lost more fat and maintained or even increased muscle mass, whereas participants who did not exercise or who only did aerobic activity lost a substantial portion of muscle along with fat.

“Although total weight loss was similar among all participants, the key difference lay in the composition and quality of that loss,” the team said. “Weight loss without strength training, and even with aerobic activity alone, was accompanied by loss of muscle mass. Strength training led to weight loss based primarily on fat, while preserving and even increasing muscle. This makes weight loss healthier, more stable, and more effective in the long term.”

The study emphasizes that muscle preservation is critical for metabolism and long-term weight maintenance. Muscle accounts for roughly 40% of body weight and drives much of the body’s energy use, even at rest. Losing muscle can slow metabolism, make further weight loss more difficult, and increase the likelihood of regaining weight after dieting. Strength training, the researchers note, can even help adults gain muscle while in a calorie deficit, which was previously thought to be difficult.

Strength training also produced the largest reductions in waist circumference, a key marker of abdominal fat and cardiometabolic risk. These reductions were closely linked to fat loss, showing that resistance exercise benefits not only appearance but also heart and metabolic health.

Beyond the study’s scientific findings, these results offer clear guidance for anyone looking to lose weight in a healthy, sustainable way.

The research highlights the importance of adding strength training to any weight-loss plan. Resistance exercises — like weightlifting or bodyweight workouts — help burn fat while preserving or building muscle, whereas dieting alone or aerobic activity can cause muscle loss and slow metabolism.

The findings also show that the quality of weight loss matters more than the number on the scale. Focusing on fat loss and muscle preservation, rather than just total kilograms lost, leads to healthier, more sustainable results and lowers the risk of regaining weight.

Gepner stressed that these findings should reshape how people approach dieting. “Weight loss should not be measured only by kilograms lost, but by the quality of that loss,” he said. “When proper nutrition is combined with strength training, fat can be reduced effectively while preserving and even improving muscle mass. Muscle is essential for metabolism, daily functioning, and long-term weight maintenance. Strength training is not just for athletes — it is a vital tool for anyone who wants to lose weight in a healthy, safe, and sustainable way, women and men alike.”

The study was published in the peer-reviewed Frontiers in Endocrinology.