A long-term study of more than 7,000 adults in the UK suggests that improving diet quality and increasing physical activity at the same time may be more effective at limiting weight gain than changing either habit on its own. The research, published in JAMA Network Open, found that people who improved both behaviors gained less total body fat and less visceral fat, the type stored around abdominal organs.
Visceral fat is linked to conditions like type 2 diabetes, fatty liver disease and heart disease, while subcutaneous fat, stored under the skin, is generally considered less harmful. Understanding how everyday habits influence where fat is stored can help guide more effective strategies for healthy aging.
The study followed 7,256 adults from the Fenland Study for an average of seven years. Participants wore heart rate and movement sensors for at least 72 hours at the beginning and end of the study to measure changes in physical activity. Diet quality was assessed using a food frequency questionnaire that evaluated adherence to a Mediterranean-style pattern focused on fruits, vegetables, whole grains, legumes, nuts and olive oil, with smaller amounts of fish, poultry, dairy and eggs. Red meat and sweets were more limited.
Researchers used DEXA scans to measure body fat distribution and ultrasound to assess signs of fatty liver disease. They found that improvements in diet quality and increases in activity were each independently associated with reductions or smaller gains in body fat over time. But the combination of both habits led to the largest differences.
“We found that combining a better diet with more physical activity is an effective way to improve not just weight, but how much and where fat is stored in the body,” said first author Dr. Shayan Aryannezhad from the MRC Epidemiology Unit at the University of Cambridge. “It’s particularly effective at reducing the build-up of harmful fat around organs.”
Participants who improved both behaviors gained about 1.9 kg less total body fat and 150 g less visceral fat than those who did not make changes. That difference represented roughly 7% of baseline total body fat and 16% of baseline visceral fat in the study population.
Senior author Professor Nita Forouhi said the findings support small, sustainable shifts.
“Despite the challenges of living in environments that promote unhealthy eating and inactivity, there is benefit from making small, sustained changes that lead to both healthier diets and increased energy expenditure,” she said.
The authors note that the study measured associations rather than direct cause-and-effect and that changes occurred over several years. Still, the results highlight how combining dietary improvements with more movement may support healthier fat distribution and help prevent metabolic disease.
This research was funded by the Medical Research Council and the Wellcome Trust, with additional support from the NIHR Cambridge Biomedical Research Centre.