Link to CBS report.1. Sleep debt. Getting too little sleep can increase body weight. Today's Americans get less shut-eye than ever.
2. Pollution. Hormones control body weight. And many of today’s pollutants affect our hormones.
3. Air conditioning. You have to burn calories if your environment is too hot or too cold for comfort. But more people than ever live and work in temperature-controlled homes and offices.
4. Decreased smoking. Smoking reduces weight. Americans smoke much less than they used to.
5. Medicine. Many different drugs — including contraceptives, steroid hormones, diabetes drugs, some antidepressants, and blood pressure drugs — can cause weight gain. Use of these drugs is on the upswing.
6. Population age, ethnicity. Middle-aged people and Hispanic-Americans tend to be more obese than young European-Americans. Americans are getting older and more Hispanic.
7. Older moms. There's some evidence that the older a woman is when she gives birth, the higher her child's risk of obesity. American women are giving birth at older and older ages.
8. Ancestors' environment. Some influences may go back two generations. Environmental changes that made a grandparent obese may "through a fetally driven positive feedback loop" visit obesity on the grandchildren.
9. Obesity linked to fertility. There's some evidence obese people are more fertile than lean ones. If obesity has a genetic component, the percentage of obese people in the population should increase.
10. Unions of obese spouses. Obese women tend to marry obese men. If there are fewer thin people around — and if obesity has a genetic component — there will be still more obese people in the next generation.
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