Why are there fewer obese children in France than in other Western European countries?

Abstract

In a recent paper reporting the worldwide prevalence of overweight and obesity in children from 1980 to 2013, France was shown to have one of the lowest levels in Western Europe 1. This survey of obesity and overweight in children and young people under the age of 20 performed in 22 European countries showed that France was ranked 18th for males and 22nd for females 1. But how can we explain this distinctive pattern in France? More effective prevention appears to be the main reason. The French authorities maintain that the lower prevalence of childhood obesity is to due to the French National Nutrition and Health Programme, which has been operating throughout France since 2001. This programme included widespread claims to promote healthy dietary habits, multiple school interventions and changes in the built environment to promote physical activity. Numerous healthcare professionals involved in school-based obesity prevention programmes also suggest that their actions have had a positive impact 2, 3. However, better childhood obesity prevention does not seem to explain the low rates of overweight and obesity in French children. It would be truly surprising whether educational interventions aimed at preventing childhood obesity had been successful in France even though they dramatically failed worldwide 4, 5. France was one of the first countries in the world to implement national actions to reduce childhood obesity. The instigators were hopeful that the initiatives, which cost the country a lot of money, would be successful. So, when the prevalence of childhood overweight started to plateau in France at the beginning of the 2000s, the instigators of these national prevention programmes saw it as a result of their commitment. Unfortunately, the same evolution was observed in many industrialised countries all over the world 6, clearly demonstrating that it was a spontaneous phenomenon, independent of the preventative initiatives implemented in France. Moreover, France already had one of the lowest rates of childhood obesity in Europe in 2001–2002 when the programme was launched 7, confirming that these two observations were unrelated. In addition, some French studies had showed that programmes that aimed to prevent childhood obesity had proved successful 2, 3, 8. However, there could be some obvious biases that explain why the authors of these studies assumed that their programme was working. One of the best examples was the Fleurbaix-Laventie Ville Santé study, a nutritional and physical activity educational programme, which was set up in two small towns in northern France in the early 1990s and led to the famous EPODE international obesity network being established in many countries all over the world 8. The educational programme began in 1992 and a follow-up survey was carried out for 12 years until 2004. The authors reported that the prevalence in childhood overweight increased from 1992 to 2000 and then the trend plateaued and reversed. During the same period of time, a similar evolution of prevalence has been observed in the rest of the country and many other nations in the world 6, therefore all of these results cannot be the positive outcomes of preventive interventions. It would have been useful to have compared the evolution of obesity prevalence during the 12-year follow-up period with a control group, but that comparison was not made. A number of other biases invalidate the positive results demonstrated in other French studies, including inadequate selection of the control population and lack of important data that would enable researchers to compare the intervention children and controls, such as the parents' body mass index and ethnicity 2, 3. If paediatric obesity prevention programmes cannot explain the lower prevalence of childhood obesity in France, another possible reason could be that French children are less at risk of becoming obese. There is now considerable evidence that a constitutional susceptibility to weight gain is necessary to become obese under the pressure of an obesogenic environment 9. In other words, only children who are programmed to develop obesity are at risk and the availability of lots of food or inactivity has no effect on children who are not programmed to become obese. Strong lines of evidence also support the contention that individual differences in the predisposition to weight gain rely on personal genetic profiles, including the metagenome of microbiota. More sound research should, however, be conducted to identify the exact genetic origin of childhood obesity. A careful analysis of the differences between the prevalence of childhood overweight and obesity in countries all over the world 1 strongly supports the programming hypothesis as an explanation for the lower prevalence in French children. Much higher rates of paediatric overweight and obesity are observed in countries such as Kiribati, Samoa, Tonga and Chile than in the USA or Europe 1. Obviously, the pressure of the obesogenic environment is much less important in those countries than in the latter two, one might consider that prevention programmes are also missing in those developing countries. However, prevention is poor in many other countries, such as Romania, Colombia, Panama and Moldova, and they have substantially lower childhood overweight and obesity rates than the USA and most of Europe. Finally, a different genetic susceptibility appears to be the most likely explanation for the variation in the prevalence between the countries. Another argument that advances the strong genetic influence on childhood adiposity is racial disparities in obesity. Overweight prevalence has been much higher in black American children than white ones for many decades, and the trend has been getting worse 10. One might suggest that this disparity could be due to differences in socioeconomic status. But, interestingly, black children with a high socioeconomic status face an increased risk of being overweight, while a reverse association exists in white children. This strongly suggests that being overweight is more likely to be due to ethnicity than either environmental or socioeconomic status. Because French paediatricians are not allowed to record ethnicity, this kind of data is not available in France. However, many French paediatricians notice a higher prevalence of overweight in French black and North African children. However, we cannot rule out a higher level of discrimination against obese people in France than in other European countries. The French do have a tendency to be obsessed with thinness and this can lead adolescents, especially girls, to pursue restrictive diets. It is possible that it is more common for moderately overweight adolescents to lose weight in France and this reduces the number that is overweight. Greater discrimination against obese adults could also decrease their sex appeal and their chances of procreating and having children who are more at risk of becoming overweight or obese. Nevertheless, these hypotheses are pure speculation and require confirmation. We can also speculate that the culture of eating in France may play a role in explaining the lower prevalence of childhood obesity. Indeed, children begin to eat regular meals with their families at an early age in France, in contrast to other countries, such as the USA or United Kingdom, where children eat more snacks between meals. But longitudinal genetic studies strongly suggest that the body mass evolution over time is primarily a function of genotype rather than a persistent effect of early learning on eating habits 4. Breastfeeding is widely believed to provide a protective effect against obesity. It is therefore surprising that France exhibits one of the lowest rates of breastfeeding in Europe 11. One might speculate that breastfeeding accustoms infants to on demand feeding, which may lead them to eat more snacks between meals, but this argument cannot be sustained. On the other hand, this other French paradox supports the opinion that breastfeeding does not have important antiobesity effects 4. In conclusion, as a French paediatrician, I wish that I could have demonstrated that the lower prevalence of overweight and obese children in my country was the result of an effective prevention programme conducted by French authorities. I wish that I could also have shown that French people are more disciplined than their European neighbours when it comes to following healthy diets. Unfortunately, my scientific integrity compels me to come to the conclusion that French people are not superior to other European individuals. In all probability, they are just less genetically predisposed to obesity.