A large Spanish study followed nearly 5,000 adults with metabolic syndrome for 6 years to see if combining a Mediterranean diet with calorie reduction and exercise could prevent type 2 diabetes better than just following a Mediterranean diet alone. The results were impressive: people who followed the enhanced approach with fewer calories and more physical activity had a 31% lower risk of developing diabetes. This suggests that while the Mediterranean diet is beneficial on its own, adding structured weight loss and exercise makes it even more powerful for diabetes prevention.

The Quick Take

  • What they studied: Whether combining a calorie-reduced Mediterranean diet with exercise prevents diabetes better than just following a regular Mediterranean diet
  • Who participated: 4,746 Spanish adults aged 55-75 with metabolic syndrome and excess weight, but no existing heart disease or diabetes
  • Key finding: The enhanced approach reduced diabetes risk by 31% compared to the Mediterranean diet alone over 6 years
  • What it means for you: If you’re at risk for diabetes, combining Mediterranean eating with portion control and exercise may be more protective than diet changes alone

The Research Details

This was a randomized controlled trial, considered the gold standard for medical research. Researchers randomly divided participants into two groups: one followed a Mediterranean diet with 600 fewer calories per day plus increased physical activity, while the other group followed a regular Mediterranean diet without calorie restrictions. Both groups were followed for 6 years to track who developed diabetes. The study was conducted across 23 medical centers in Spain, ensuring diverse participants and robust data collection.

This design allows researchers to directly compare the two approaches while controlling for other factors that might influence diabetes risk. By randomly assigning people to groups, the study minimizes bias and provides strong evidence about cause and effect.

The large sample size of nearly 5,000 people and 6-year follow-up period provide reliable results. However, participants knew which group they were in, which could influence their behavior. Also, dietary adherence was self-reported, which may not be completely accurate.

What the Results Show

Over 6 years, 12% of people following the regular Mediterranean diet developed diabetes, compared to 9.5% in the enhanced group. This translates to a 31% relative reduction in diabetes risk. In practical terms, for every 1,000 people following the enhanced approach for one year, about 3 fewer cases of diabetes would occur compared to the regular diet group. The intervention group also achieved better adherence to Mediterranean diet principles, increased their physical activity levels more, and lost more weight and inches around their waist.

Participants in the enhanced group showed greater improvements in multiple health markers beyond just diabetes prevention. They had more significant reductions in body weight and waist circumference, suggesting better overall metabolic health. The group also demonstrated higher adherence to Mediterranean diet patterns, indicating that the structured approach helped people stick to healthy eating habits.

Previous research has shown that Mediterranean diets can help prevent diabetes, but this study provides new evidence that adding calorie control and exercise makes the approach even more effective. This builds on existing knowledge by showing that lifestyle interventions work best when they address multiple factors simultaneously rather than focusing on diet alone.

Since this was a secondary analysis of a larger study, diabetes prevention wasn’t the original primary goal. Participants couldn’t be blinded to their treatment group, which might have influenced their behavior. Dietary information was self-reported, which may not be completely accurate, and the study only included older Spanish adults with metabolic syndrome, so results may not apply to everyone.

The Bottom Line

For people at high risk of diabetes, especially those with metabolic syndrome and excess weight, combining Mediterranean eating patterns with moderate calorie reduction and increased physical activity appears more effective than dietary changes alone. The approach seems most beneficial when all three elements work together: healthy food choices, portion control, and regular exercise.

This research is most relevant for adults over 55 with metabolic syndrome and excess weight who want to prevent diabetes. People with existing diabetes or heart disease should consult their healthcare provider before making significant lifestyle changes. Younger adults or those without metabolic risk factors may still benefit, but the results may not be as dramatic.

Diabetes prevention benefits appeared to accumulate over the 6-year study period, suggesting this is a long-term lifestyle approach rather than a quick fix. Participants likely saw weight loss and other health improvements within months, but the diabetes prevention benefits required sustained commitment to the lifestyle changes.

Want to Apply This Research?

  • Track daily calories with a target of 600 calories below your maintenance level, Mediterranean diet adherence score, and weekly physical activity minutes
  • Gradually implement Mediterranean diet principles while creating a moderate calorie deficit and increasing physical activity by 150 minutes per week
  • Monitor weight loss progress, waist circumference changes, and blood sugar levels quarterly while tracking daily food choices and exercise consistency

This information is for educational purposes only and should not replace professional medical advice. Consult your healthcare provider before making significant dietary or exercise changes, especially if you have existing health conditions or take medications.