The International Association for the Study of Obesity estimated in 2006 that the number of obese school age children in Europe increased by almost 50 per cents since the late 1990s. The associatation projected that as many as 6.4m European kids could be obese by 2010.
The number who are overweight is expected to grow by 1.3 million a year to a total of 26 million across the EU in four years, more than one-third of the child population, the (IASO) says.
Much of the work towards combating childhood obesity to date has centered on the food eaten by children, as well as marketing and availability of less wholesome products, and parental choices. If the results of the new study, conducted by researchers at Rockerfeller University, also hold for humans, they could move the debate forward a step, towards the diet of mothers themselves.
Led by Sarah Leibowitz of the Laboratory of Behavioral Neurobiology, the researchers investigated the effects on offspring of feeding pregnant rats a high fat diet for two weeks compared with a balanced diet containing a moderate amount of fat.
They found that the young of the rats that consumed the high fat diet tended to eat more and weighed more all throughout their life – even though they were not fed the high fat diet after birth.
They were also seen to have higher levels of triglycerides in the blood at birth; they tended to begin puberty earlier than the rats whose mothers received the normal-fat diet; and greater production of brain peptides that stimulate eating and weight gain.
The next step for Leibowitz and her team was to investigate development of the young rats’ brains in the last week of pregnancy, by examining the number and types of neurons being born.
Those born to the high-fat mothers fat more neurons that produce the appetite-stimulating orexigenic peptides both in utero – and throughout their lives.
The mother's fat-rich diet was also seen to stimulate proliferation of neuronal precursor cells, and their migration to obesity-promoting centers in the brain.
"This work provides the first evidence for a fetal program that links high levels of fats circulating in the mother's blood during pregnancy to the overeating and increased weight gain of offspring after weaning,” said Leibowitz.
While no mechanism had been found until now, previous studies have observed the greater likelihood of obese and diabetic mothers producing heavier children, as well as the tendency for fat-rich foods early in life leads to lead to obesity later on.
"We believe the high levels of triglycerides that the fetuses are exposed to during pregnancy cause the growth of the neurons earlier and much more than is normal," says Leibowitz.
She thinks it would make sense that similar mechanisms are in operation in humans:
"We're programming our children to be fat," she said. "I think it's very clear that there's vulnerability in the developing brain, and we've identified the site of this action where new neurons are being born.”
The researchers hypothesize that because the mother must prepare her embryos to survive on her diet, they need to be born with the brain mechanisms that allow them to eat and metabolize it.
Liebowitz said that the next stage in the research is to understand how the lipids affect these precursor cells that form fat-sensitive neurons.
The research, supported by the National Institutes of Health, is published in the November 12 issue of the Journal of Neuroscience. Full reference was not available at the time of publication of this article.