Scientists: losing weight protects health even if the weight has come back on

A new study by Swedish scientists has proved that even if a person regains weight after weight loss, the health benefits remain. This applies to those who have lost a significant amount of weight after weight loss surgery, but later regain some of the lost kilograms.

Researchers from the University of Gothenburg studied data from 1,346 people who had undergone surgical treatment for obesity. During the first year after surgery, the participants lost an average of about 30 kilograms in weight. However, after four years, more than half of them had regained at least 20 per cent of the weight they had lost.

The researchers divided the participants into two groups: those who managed to maintain their new weight and those who significantly regained it. The scientists then analysed how this affected their health by comparing the incidence of cardiovascular disease, cancer, microcirculatory disease (problems with small blood vessels) and mortality rates.

It turned out that gaining weight again had no effect on cancer risk or life expectancy. In other words, people who gained weight again had the same chances of living a long life and avoiding cancer as those who kept the weight off.

However, the situation was worse for small blood vessel diseases (such as kidney or eye problems). Those who gained weight had a higher incidence of these diseases - about 11 cases per 1,000 people per year, compared with 8.7 cases in people with maintained weight loss.

The risk of cardiovascular disease also increased slightly in those who gained weight: 15.7 cases versus 13 per 1,000 people per year.

The study authors note that weight loss still has long-term benefits. Even if it is not possible to keep the weight at the minimum mark, the body manages to get a positive effect that lasts for a long time.

We now know that weight loss is beneficial in any case. Even if the person gains weight again, the benefits remain, such as a reduced risk of cancer and the same life expectancy," emphasises the author of the study, Associate Professor Kajsa Sjöholm.

Nevertheless, doctors recommend avoiding a sharp return of extra kilos, as it worsens the quality of life, increases the risk of cardiovascular and other diseases and creates psychological discomfort.

Details: Lena M.S. Carlsson et al, Health outcomes and their association with weight regain after substantial weight loss in Sweden: a prospective cohort study, The Lancet Regional Health - Europe (2025). DOI: 10.1016/j.lanepe.2025.101261