New research shows that children who follow a Mediterranean diet, especially when they consume nuts and vegetables, may have less weight gain, but the overall effects are modest after baseline BMI.
Population Study Article: Adherence to the Mediterranean diet and changes in body mass index. Image credit: Tverdokhlib / Shutterstock
In a recent study published in the journal Pediatric Researchresearchers examined how following a Mediterranean diet affects changes in standardized body mass index (zBMI) and children’s risk of becoming overweight. While adherence to the Mediterranean diet was associated with protection against high zBMI increases, these effects were modest and lost statistical significance after adjustment for baseline zBMI.
Their findings suggest that eating specific Mediterranean diet foods, such as yogurt or cheese, nuts, and vegetables, may protect children from large increases in zBMI, although the overall effect size was small.
Background
Childhood obesity rates have increased significantly worldwide, making it a major public health issue. In Spain, childhood obesity and overweight have remained above 30% for the past 20 years, with recent figures suggesting that almost 41% of children between the ages of six and nine are overweight and 17% obese.
Childhood obesity can continue into adolescence and adulthood. Estimates show that 55% of obese children may remain obese during adolescence and that 80% of obese adolescents will remain obese into adulthood.
Behavioral, environmental and genetic factors contribute to obesity. Researchers have identified low self-esteem, poor sleep, unhealthy diet and physical inactivity as modifiable risk factors. For children, lack of physical activity and unhealthy or fattening food are the main factors of obesity.
The Mediterranean diet, which is rich in fiber, antioxidants, healthy fats and plant-based proteins, is a balanced diet that may have benefits for weight management in children and has been shown in some studies to reduce body mass index (BMI ). However, more evidence is needed to fully understand its effect on childhood obesity.
About the study
The study included 1,389 children aged between eight and ten from four municipalities in Spain between 2012 and 2014, with follow-up after 15 months. The children participated voluntarily and with the permission of their parents.
At the start of the study, their waist circumference, height and weight were measured and changes in BMI were used to calculate zBMI. A BMI greater than one standard deviation was categorized as overweight while a BMI greater than two standard deviations was considered obese.
Children’s adherence to the Mediterranean diet was assessed using a validated questionnaire that trained researchers administered in schools, with higher scores reflecting greater adherence.
The researchers also used questionnaires to measure physical activity in the past week, time spent watching TV, using mobile devices and playing video games. Socioeconomic status was ascertained based on mother’s education.
Statistical analysis included the use of multiple linear and logistic models to examine the relationship between adherence to the Mediterranean diet and changes in zBMI, taking into account lifestyle factors such as baseline zBMI, screen time, physical activity, school environment. and maternal education.
Findings
At the start of the study, 9.4% of children showed low adherence to the Mediterranean Diet, while 49.5% had moderate adherence and 41.2% had high adherence.
During follow-up, dietary adherence decreased, as did zBMI. However, physical activity, screen time and BMI showed increases. During the study, 66 new cases of overweight were reported, including 64 cases of overweight and 2 cases of obesity, but the sample size limited the statistical power of this finding.
The researchers found that certain foods from the Mediterranean diet eaten in specific amounts were associated with a lower likelihood of increasing zBMI, including eating nuts two or three times a week and cheese or yogurt and cooked or fresh vegetables daily.
Children who showed high or moderate dietary adherence at baseline were less likely to have high increases in zBMI, but these results were not statistically significant after adjustments.
Linear regression showed that as the baseline Mediterranean diet adherence score increased by one point, zBMI decreased. However, this association weakened and became statistically insignificant after accounting for zBMI at baseline.
There were no significant non-linear relationships between diet adherence and changes in zBMI. However, children with compliance scores between 4 and 10 showed slight decreases in zBMI. No significant relationships were observed between diet adherence and the incidence of overweight.
conclusions
Previous studies, including those involving children from North America and Europe, have found associations between adherence to the Mediterranean diet and lower BMI, but research involving Spanish adolescents showed inconclusive results. Although some foods were associated with a lower likelihood of high increases in zBMI, the overall effect was modest, and similar studies in the past have shown inconsistent results.
While strengths of the study include the large sample size, prospective design, and dose-response analysis, the researchers noted some limitations. Reliance on self-reported dietary data introduces potential biases due to memory errors or social desirability.
The questionnaire also included general food descriptions and missed some important components of the Mediterranean diet. The study also did not take into account energy intake and other socioeconomic factors other than the mother’s education.
More high-quality, long-term studies are needed to provide stronger evidence about the role of the Mediterranean diet in reducing childhood overweight and obesity.
