Did you start putting on weight when you reached middle age (assuming you have reached middle age)?
If so, scientists now think they have an explanation for why that happens, and it's not your fault.
According to scientists at Monash University in Australia, "key appetite control centers" in the brain degenerate with time, so we feel hungrier than we did when we were younger. Neuroendocrinologist Zane Andrews said that the degeneration of the appetite control centers occurs to a greater extent after meals rich in carbohydrates and sugars.
If this turns out to be true, it could be one reason why Americans are getting fatter. For the past decades, nutritionists and the US Department of Agriculture, with its Food Pyramid, have been urging everyone to eat more carbohydrate and less fat. "Make starch the star," they've told people with diabetes, despite the fact that it's starch that makes blood glucose levels go up the most.
"A diet rich in carbohydrate and sugar that has become more and more prevalent in modern societies over the last 20 to 30 years has placed so much strain on our bodies that it's leading to premature cell deterioration," Dr Andrews said.
However, this alone doesn't explain why some cultures that have always eaten carbohydrate-rich diets, for example Asian populations that eat a lot of rice, did not have a lot of obesity until recent years. It's possible that when food is scarce, it doesn't matter how hungry you are; you can't overeat. When food becomes more abundant, increased hunger will be more important.
Other factors in our modern environment may also affect how easily we gain weight. Some people think that pollutants, including bisphenol-A, the hormone mimic that can leach from plastic bottles, may be a culprit.
A recent study showed that bisphenol-A reduced the amount of the hormone adiponectin, a hormone thought to decrease a person's risk of diabetes. The study authors said that bisphenol-A can increase insulin resistance in mice, and insulin resistance is thought to contribute to obesity.
Bisphenol-A has been blamed for other health problems as well.
No one knows how important these various factors are in contributing to rising obesity rates, but there are undoubtedly many factors at work. Until they're all worked out, you can't go wrong eating home-cooked (ideally home-raised) real foods instead of processed foods or restaurant foods. You can't go wrong washing your fruits and vegetables to remove as much of the pesticides as you can (assuming your water supply is safe). You can't go wrong eating on real china instead of plastic plates. You can't go wrong avoiding microwaving foods in plastic.
And encouraging your children and grandchildren to do the same may help them prevent becoming another statistic in the obesity and diabetes epidemic.