Obesity risk raised despite diet.
Now this research concerns itself with non-human animals (mice specifically), but it does provide interesting insight into the non-diet factors which may be at play in soaring obesity rates and the way environmental pollution influences development: A new study shows that exposure to polluted air early in life, at levels that correspond to the amount of fine particulate pollution found in many US cities, can lead to increased accumulation of abdominal fat and insulin resistance, even if a healthy diet is followed.
That’s the world from researchers who exposed three-week old mice to polluted air for six hours a day, five days a week, for 10 weeks–a time period roughly corresponding in humans from being a toddler to adolescent.
The mice exposed to the polluted air had larger and more fat cells in their abdomens and higher blood sugar level than did mice fed exactly the same diet but which breathed clean air.
[Lead researcher Qinghua] Sun and colleagues fed the mice with either a normal diet or a high-fat diet and exposed them to either filtered air or air containing at least seven times more fine particulates than the ambient air in Columbus, Ohio. On average, the ambient air contained 15.8 micrograms of fine particles per cubic meter, compared to 111 micrograms per cubic meter in the concentrated air to which the mice were exposed…Mice on the high-fat diet gained much more weight than those on the normal diet. But mice exposed to polluted air and eating the normal diet had more significant elevations in glucose — sugar in their blood — than did normal-diet mice that breathed clean air. They also showed more signs of insulin resistance based on an index that measures both sugar and insulin in the blood at the same time.
In addition, both abdominal and subcutaneous (under the skin) types of fat were increased with exposure to pollution in mice, even in animals that ate the normal diet. Mice eating a high-fat diet also had more fat, but their exposure to polluted air did not exacerbate those effects.