By Harshit
NEW YORK, Nov. 29 — 2 AM EDT
A major new study has delivered one of the clearest answers yet to a longstanding public-health question: Is it diet or exercise that prevents abdominal fat gain — or do you need both?
According to research published this month in JAMA Network Open, improving both diet quality and physical activity simultaneously is significantly more effective at preventing the accumulation of visceral fat — the deeper, more harmful fat stored around internal organs — than focusing on diet or exercise alone.
The findings carry weight well beyond appearance. Visceral fat has been repeatedly linked to elevated risks of type 2 diabetes, heart disease, stroke, fatty liver disease, sleep apnea, cancer, and Alzheimer’s disease.
A Growing Global Health Burden
Nearly 3 billion people worldwide are living with overweight or obesity. For many, weight gain happens slowly and silently over years, especially around the abdomen.
Dr. Shayan Aryannezhad, lead author of the study and researcher at the University of Oxford, said the goal was to understand how everyday lifestyle habits influence fat storage — and which habits matter most.
“Visceral fat is especially harmful,” he explained. “Finding effective ways to prevent its buildup is critical if we want to reduce cardiometabolic disease risks.”
A Unique Study Design
Researchers analyzed data from more than 7,000 adults in the long-running Fenland Study in the United Kingdom. Participants, with an average starting age of 49, were monitored for seven years.
Each participant completed:
- A DEXA scan to precisely measure total and visceral fat
- A 72-hour physical activity assessment
- A dietary evaluation based on adherence to a Mediterranean diet
Unlike many long-term studies, this one analyzed diet and exercise together, not in isolation.
“People don’t live their lives in separate behaviors,” Aryannezhad said. “When we study diet and movement side by side, the patterns become much clearer.”
Combined Diet + Exercise Delivered the Best Results
At the end of the follow-up period, researchers found that participants who improved both lifestyle factors saw the largest benefits:
On average, they gained:
- 1.9 kg less total body fat, and
- 150 grams less visceral fat
…compared with people who did not improve either behavior.
This may sound small, but it represents:
- About 7% less total body fat, and
- Roughly 16% of the group’s average visceral fat volume
Those improvements translate to real reductions in long-term disease risk, researchers said.
Why Both Lifestyle Changes Matter
Participants who improved only diet or only exercise still saw modest health improvements. But the combined approach produced significantly stronger effects.
Experts say this happens because focusing on one habit often triggers compensations in the other.
For example:
- People who exercise more may eat more.
- People who cut calories may move less.
Targeting both habits avoids this compensation effect.
“It’s not about picking diet or exercise,” Aryannezhad said. “They work best when they work together.”
What Doctors Say
Dr. Mir Ali, a bariatric surgeon in California, said the findings reinforce what clinicians see every day.
“Visceral fat is linked to some of our most serious diseases,” he said. “Any strategy that reduces it is valuable. This study shows that combining lifestyle interventions is the most powerful.”
Dr. Seth Kipnis, a bariatric surgeon in New Jersey, said the DEXA-scan data make the findings especially compelling.
“Patients often focus on what they can see in the mirror,” he said. “But visceral fat — the fat you can’t pinch — is what drives metabolic disease. This study’s approach directly measures that risk.”
A Motivating Message for Millions
Encouragingly, the largest improvements were seen among people who were:
- Overweight
- Inactive
- Or both
In other words, the people who needed the most help benefited the most.
“This should give hope to anyone who feels stuck,” Kipnis said. “Small, consistent changes in diet and movement really do add up.”