A long-term study led by researchers at the University of Helsinki has found that overweight adults who lose a modest amount of weight in early middle age and keep it off can enjoy significant long-term health benefits.
The research tracked over 23,000 individuals from Finland and the UK, aged 30 to 50 at the start of the study, for a period of 12 to 35 years. It showed that those who lost around 6.5% of their body weight and maintained that loss experienced improved health and increased longevity.
The study is one of the first to clearly show long-term health benefits of lifestyle-based weight loss beyond just the prevention of diabetes. While many health experts promote weight management through diet and exercise, solid evidence proving its wider benefits over decades has been limited—until now.
Professor Timo Strandberg, who led the study, highlighted this gap: “The benefits of lifestyle-based weight management are widely discussed even though studies have found it surprisingly difficult to demonstrate health benefits beyond the prevention of diabetes.”
This new research offers stronger proof that modest weight loss and weight stability over time can truly make a difference.
One of the key takeaways from the study is the importance of maintaining weight loss. Participants who were able to keep the weight off over many years were the ones who saw the most positive outcomes. In other words, it’s not just about losing weight—it’s about keeping it off for good.
This finding is particularly timely, as rates of overweight and obesity have risen sharply since the research data was first collected over three decades ago. “I hope the findings will inspire people to see that lifestyle changes can lead to major health improvements and a longer life,” said Professor Strandberg.
The study also reinforces the widely accepted health goal of keeping body mass index (BMI) under 25 for optimal wellbeing. BMI is a measurement that uses height and weight to estimate body fat. A BMI under 25 is considered to be in the healthy weight range.
The research was published in JAMA Network Open, the open-access journal of the American Medical Association.
It adds strong evidence to the idea that steady, moderate weight loss and long-term weight maintenance—not extreme diets or short-term fixes—can play a powerful role in improving health and extending life, especially for people who start out overweight in midlife.
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The research findings can be found in JAMA Network Open.
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