1. Lack of physical exercise. Everybody knows this, but why? For one thing, they have cut funding for physical education programs in our schools. I remember when I was in 5th grade (1962), and President Kennedy was shocked at how out of shape America’s children were. He initiated a program to get Americans in shape. I have to say it helped.

2. Air conditioning. When we are cold, our body burns more calories to keep warm. Of course this tends to make us hungrier too, so I’m not sure how this works out overall. But when we are hot, we tend to eat less.

I had read an article about how animals have responded to previous global warming events. They get much smaller. This made me wonder whether there might be a connection between air conditioning and obesity. A brief internet search confirmed that there is indeed a possible link.

3. I just read about this one. Obese people have different organisms in their guts than normal people. The cause of this correlation is not yet known. It may be that the different organisms cause the obesity, or it may be that they flourish in obese people.

4. Growth hormones in our food. It is cheaper to grow meat by giving the animals growth hormones in their food. It is not too much of a stretch to think that perhaps some of these growth hormones are not fully metabolized and we end up eating them.