A Mediterranean lifestyle obesity prevention intervention in preschoolers at risk: MELI-POP Study-a randomized controlled trial.

The MELI-POP RCT enrolled 206 preschool children aged 3.0–6.9 years at risk of obesity due to family history, with 170 completing the 12-month study.

• Participants were recruited from health centers, hospitals, and schools in three Spanish cities.
• Inclusion criteria required normal weight or overweight status and at least one parent with overweight or obesity.
• The study had a 17.5% dropout rate (206 enrolled, 170 completed).
• Participants were randomly assigned to either a Mediterranean lifestyle intervention or a control group in a parallel RCT design.
• The trial was registered at ClinicalTrials.gov: NCT04597281, registered 28-09-2020.

The Mediterranean lifestyle intervention consisted of fish and olive oil provision, monthly nutrition education sessions, and twice-weekly physical activity sessions.

• The intervention group received provision of fish and olive oil as dietary components.
• Nutrition education was delivered monthly.
• Physical activity sessions were conducted twice per week.
• The control group received general child health advice unrelated to diet or exercise.
• The intervention duration was 12 months.

No significant differences between intervention and control groups were observed at baseline.

• Baseline measures included BMI, fat mass index (FMI), waist-to-height ratio, blood pressure, lipid profile, glucose, and insulin.
• Primary outcomes were BMI, FMI (kg/m2 and z-scores).
• Secondary outcomes included waist-to-height ratio, blood pressure, lipid profile, glucose, and insulin.

The Mediterranean lifestyle intervention produced significant improvements in BMI and fat mass index in girls but not in boys.

• Per-protocol analysis showed significant differences in BMI and FMI (kg/m2 and z-score) between intervention and control groups among girls.
• No significant between-group differences in BMI or FMI were observed among boys in per-protocol analysis.
• Intention-to-treat analysis confirmed the sex-specific findings observed in per-protocol analysis.

Intention-to-treat analysis showed significant reductions in BMI and BMI z-score in girls in the intervention group compared to controls.

• Girls in the intervention group showed a significant change in BMI of -0.68 kg/m2 compared with the control group.
• Girls in the intervention group showed a significant change in BMI z-score of -0.34 compared with the control group.
• These findings were consistent between per-protocol and intention-to-treat analyses.

No significant between-group differences were observed in cardiovascular risk factor changes in either per-protocol or intention-to-treat analyses.

• Cardiovascular risk factors assessed included waist-to-height ratio, blood pressure, lipid profile, glucose, and insulin.
• This null finding was consistent across both per-protocol and intention-to-treat analyses.
• The lack of effect on cardiovascular risk factors applied to the full study sample regardless of sex.

This is described as the first randomized controlled trial evaluating the effectiveness and efficacy of a Mediterranean lifestyle prevention intervention including both diet and physical activity in preschool children at risk of obesity.

• The study included fat mass index (FMI) and FMI z-score to enable more specific characterization of adiposity-related changes complementing BMI-based outcomes.
• Prior Mediterranean diet-based interventions have shown benefits in reducing BMI and obesity in children and adolescents, but fewer have reported detailed body composition measures or explored potential sex-specific effects.
• The authors note that larger studies are needed to confirm the observed sex-specific results.