It's well known that poor food choices and sedentary lifestyles are the two most likely causative factors of the current epidemic of obesity.
But many scientists believe that other factors must also be involved in such a sudden and dramatic rise in obesity over the last few decades. A group of 20 obesity experts has determined the 10 most plausible additional explanations, which include:
Not enough sleep:
People who sleep less than seven hours a night tend to have a higher body mass index (BMI) than people who sleep more. This could be because sleep deprivation alters metabolism. Leptin, the hormone that signals satiety, falls while ghrelin, which signals hunger, rises -- and this boosts appetite.
Children of obese mothers are much more likely to become obese themselves. While this is likely due in part to genetics, there is also evidence of "intrauterine programming."
Many types of drugs, including neuroleptics, anticonvulsants, antihypertensives, protease inhibitors, and diabetes medications, have been shown to cause weight gain.
Low levels of industrial chemicals such as pesticides, dyes, resins and solvents can lead to weight gain. Mice given small amounts of the pesticide dieldrin more than doubled their body fat, and hexachlorobenzene, another pesticide, caused rats to gain weight even when they only ate half as much.