Healthy diet and exercise are core recommendations for weight loss, but new research details the more significant effects of the two in combination on unhealthy visceral vs subcutaneous adipose tissue, with improvements notably greater in people who have overweight and obesity.

The findings showed that “targeting improvements in diet and physical activity may be not only associated with weight loss but also particularly effective in associations with reduced metabolically harmful fat and an overall healthier adiposity profile, which could have important implications for long-term health outcomes,” reported the authors in the study, published in JAMA Network Open.

The results are from an analysis of 7256 participants enrolled in the ongoing UK population-based Fenland study between 2005 and 2020, which included repeated measurements of health behaviors and adiposity, with a mean follow-up of 7.2 years.

Participants were assessed based on their adherence to the Mediterranean diet, reported on food frequency questionnaires, while their physical activity levels were assessed and calibrated with heart rate and movement sensing.

Measures of patients’ total adiposity, including weight, BMI and body fat, and regional adiposity, including waist circumference, visceral adipose tissue, and subcutaneous adipose tissue, were assessed with anthropometry and dual-energy x-ray absorptiometry.

The patients had a mean age of 48.8 years, and 51.7% were women.

After a multivariate adjustment for key confounders, the results showed that increases in Mediterranean diet adherence and physical activity were each associated with benefits on their own.

For instance, for each increase in Mediterranean diet SD score there was a reduction in body fat of 0.47 kg as well as a reduction in visceral adipose tissue of 0.45 g.

Likewise, for each increase in physical activity energy expenditure SD score, there were similar reductions in body fat of 1.40 kg and a reduction in visceral adipose tissue of 108 g.

Importantly, however, when combined, simultaneous increases in Mediterranean diet score and physical activity energy expenditure were associated with even greater magnitudes of decrease in adiposity, with a reduction of about 1.9 kg less total body fat and 149 g in visceral adiposity tissue, or about 16% of the baseline visceral fat among participants with higher changes in Mediterranean diet scores and physical activity energy expenditure.

“Individuals who increased diet quality and activity concurrently experienced the most adiposity loss, while those who reduced both exposures had the greatest adiposity gain during the follow-up,” the authors noted.

Notably, the associations were greater among individuals who had overweight or obesity, or who were physically inactive at baseline.

For example, for each change in physical activity energy expenditure score, the reduction in body fat was 0.96 kg when baseline BMI was < 25 and the reduction was 1.74 kg when baseline BMI was ≥ 25 (P < .001).

“Our finding of an interaction between both health behaviors and baseline adiposity suggests that the potential benefits associated with improving diet quality and increasing physical activity are greater in individuals with overweight or obesity than those with reference range weight,” the authors noted.

Visceral vs Subcutaneous Fat

Importantly, improvements in diet and exercise were more associated with reductions in visceral fat, which is associated with worse health implications, such as type 2 diabetes, fatty liver disease, and heart disease compared with less detrimental subcutaneous fat, the authors noted.

“Visceral adipose fat is more metabolically active and prone to mobilization during energy deficits because it is more vascular and innervated and contains a larger number of inflammatory and immune cells compared with subcutaneous adipose tissue,” the authors explained.

Subcutaneous adipose tissue is meanwhile “less insulin resistant and serves as a more stable fat deposit.”

Overall, “total body fat and visceral adipose tissue showed the greatest degree of alternations over time, while subcutaneous adipose tissue exhibited smaller changes.”

The improvements seen even after adjusting for BMI were especially important, first author Shayan Aryannezhad, MD, PhD, of the Epidemiology Unit, Institute of Metabolic Science, University of Cambridge School of Clinical Medicine, Cambridge, England, told Medscape Medical News.

“A notable finding was that improvements in diet and physical activity remained associated with reductions in waist circumference, body fat, and visceral fat even after we adjusted for body mass index,” Aryannezhad said.

“In contrast, after adjusting for BMI, there was no association with subcutaneous fat, suggesting that improvements in behaviors may help reduce harmful fat stores while preserving the less harmful subcutaneous fat in relative terms.”

In other measures, rates of hepatic steatosis were also reduced, with an incidence rate ratio of 0.80 per 1 SD in physical activity energy expenditure and 0.89 per 1 SD in Mediterranean diet score.

There were no differences observed based on baseline menopause or hormone-replacement therapy status in female participants.

While the study did not look at what has become one of the most popular weight loss methods, GLP-1 drugs, Aryannezhad cautioned against extending the results to those patients.

“The evidence for the well documented weight loss with GLP-1 receptor agonists [RAs], comes largely from specific groups, such as people at high risk of cardiovascular disease, or adults with obesity or diabetes,” he noted.

“We therefore need to be careful about generalizing these findings to the wider population, as we studied.”

That being said, the findings underscore that “in the era of widespread GLP-1 RA drugs use, the role of healthy behaviors should not be underestimated,” Aryannezhad said. “Pharmaceutical interventions are not suitable for everyone because of eligibility, cost, potential side effects, and the risk of weight regain when treatment stops.”

“In our analysis, improvements in either diet quality or in physical activity were linked with lower adiposity and better adiposity profile over time, but doing both together was associated with a much larger benefit,” Aryannezhad added.

“Clinicians can use this evidence to highlight the value of combining a healthy diet with regular physical activity to reduce harmful fat distribution and support better metabolic health,” he said.

Additive Effects

Commenting on the study to Medscape Medical News, Dmitri Samovski, PhD, an associate professor of medicine at the Center for Human Nutrition, Washington University School of Medicine, St. Louis, said the study is important in showing that the effects of diet and increased physical activity “each independently relate to less gain or more loss in total and regional fat, and that doing both together yields the greatest overall benefit — but in an additive rather than synergistic way.”

While the stronger responsiveness of visceral vs subcutaneous fat to lifestyle change is consistent with previous evidence, “what stands out here is that visceral fat reductions remain evident even after accounting for total body fat change, suggesting some selective benefit of lifestyle improvements on the most metabolically harmful depot, whereas changes in subcutaneous fat largely track with overall fat loss,” Samovski said.

He noted that the study’s limitations include that the assessment of diet is with a food-frequency questionnaire, “so measurement error is substantial, and true diet effects may be underestimated.”

In addition, the mostly White population from one UK region limits generalizability, and as lean mass outcomes are not characterized, “the interpretation of overall ‘quality’ of weight change is limited,” Samovski said.

Overall, however, “for clinicians and patients, including those using GLP-1-based therapies, the message is that medication or diet alone is not enough: Sustained physical activity remains essential for optimizing fat distribution, preserving lean mass, and improving long-term cardiometabolic health,” he said.

Aryannezhad and Samovski had no disclosures to report.