It might also be speculated that our more pronounced association among studies with BMI assessment after the year 2000 compared to before 2000 reflects this gene-environment interaction as well: assuming that a change in nutritional habits and physical activity contributed to the increase in obesity observed in the last decades, the studies with a more recent BMI assessment might reflect this more “modern” environment and the INSIG2-obesity association would emerge here more clearly. This evidence concerns the gene INSIG2 and obesity due to melanocortin 4 receptor deficiency.