A new study from the University of Leicester has found that people who lose weight and later regain it may end up with less muscle mass than they started with—even if their overall weight returns to the same level.
The research highlights an important concern about a pattern known as weight cycling—where people repeatedly lose and regain weight—and its possible impact on long-term health.
The study was led by Professor Tom Yates and carried out by the National Institute for Health and Care Research (NIHR) Leicester Biomedical Research Centre. It focused on 622 adults who were at risk of developing type 2 diabetes.
These participants were part of a lifestyle program called Walking Away from Type 2 Diabetes, which encouraged people to be more physically active, especially by walking more.
Researchers tracked changes in participants’ weight and body composition over two 24-month periods—essentially looking at weight and body makeup across four years. They used a method called bioelectrical impedance analysis (BIA) to measure body composition, which includes both fat mass and fat-free mass.
Fat-free mass includes everything in your body that isn’t fat—such as bones, organs, and especially muscle, which makes up the largest part of it. The results were double-checked using more precise DEXA scans.
While most people in the study managed to keep their weight stable, a smaller group (about 4.5% of participants) lost more than 5% of their body weight in the first 12 months and then gained it back over the next 12 to 24 months.
The key finding? When these people regained the weight they had lost, they regained almost all of their fat, but they didn’t regain their muscle. On average, they had 1.5 kilograms (around 3.3 pounds) less fat-free mass than before. According to Professor Yates, this muscle loss is roughly equal to 10 years of aging.
This is concerning because losing muscle—especially as we get older—is a major cause of weakness and frailty. “Fat-free mass naturally declines with age,” Professor Yates explained. “But when lifestyle changes, such as weight cycling, speed up this loss, it could raise the risk of long-term problems like reduced mobility, falls, or muscle-related health issues.”
Obesity is a growing concern worldwide, and more people are turning to diet plans and weight-loss medications to help manage their weight. But as the study notes, weight regain is very common, especially after stopping a diet or medication. This research raises an important question: what is happening to people’s bodies during those weight regain phases?
The study’s findings suggest that repeated cycles of weight loss and regain may make body composition worse over time. While someone’s total weight might look “normal” or return to where it started, they could end up with more fat and less muscle—which can be harmful to long-term health.
Review and Analysis
This study shines a light on something many people overlook during dieting: what kind of weight are you losing or gaining? Losing weight might feel like a win, but if a person loses both fat and muscle, and only gains the fat back later, their body composition may get worse over time.
Muscle mass is not just important for athletes or bodybuilders—it plays a vital role in staying healthy, especially as we age. Low muscle mass increases the risk of falling, makes everyday tasks harder, and is linked with several chronic illnesses. If weight loss efforts are leading to a loss of muscle, it could have the opposite effect of what people hope to achieve.
One key takeaway from this study is that maintaining muscle should be a priority during any weight loss journey. This means combining healthy eating with physical activity, especially strength training, to help preserve or build muscle.
The study also calls for more awareness about the long-term impact of weight cycling. While diets and medications can help reduce weight in the short term, people and healthcare providers need to think carefully about strategies that support lasting, healthy weight maintenance—not just short-term loss.
In conclusion, while losing weight can be beneficial, this research suggests that how we lose and regain it matters. To support long-term health, weight management plans should focus not just on the number on the scale, but also on preserving muscle and avoiding repeated cycles of gain and loss.
If you care about weight loss, please read studies that hop extract could reduce belly fat in overweight people, and early time-restricted eating could help lose weight .
For more health information, please see recent studies about a simple path to weight loss, and results showing a non-invasive treatment for obesity and diabetes.
The research findings can be found in Diabetes, Obesity and Metabolism.
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