Fast food and too much TV time should not take all the blame for the weight problems. A group of researchers say that a number of aspects of modern living from lack of sleep to environmental chemicals and to living with air conditioning—may be closely related to the weight problems of many people.
Lack of sleep is one of factors. Researches in animals and humans suggest that a lack of sleep over a long time can increase appetite. Studies also show that many adults and children are sleeping less than they used to. In recent decades, adults have gone from sleeping for all average of nine hours to about seven hours.
There is also evidence that industrial chemicals may increase body fat. These chemicals, which are used in products, change hormonal(荷尔蒙的) activity when they get into the body. Studies suggest that people have been getting more and more of these chemicals through the food chain in recent decades.
Another factor that may be making people overweight is air conditioning. The body burns calories when forced to eat less in hot and wet weather, but air conditioning makes it unnecessary for the body to make any adjustment.
Researchers also list other possible risk factors for overweight, including more older mothers, whose children may become overweight more easily; a number of medicines which can lead to weight gain; and fewer people who smoke, since people often gain weight when they stop smoking because nicotine can make people eat less.
No one is suggesting that people should stop working and sleep more, or keep smoking. When it comes to saying any person’s weight, what really matters is how much they eat and how much of the food they use every day. That means diet and exercise are still the key.
Why does lack of sleep will result in weight problem?    (No more than 5 words)
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How long do adults averagely sleep nowadays?          (No more than 2 words)
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How do the industrial chemicals affecting our weight come into our body?
(No more than 4 words)
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What is the main idea of this passage?             (No more than 18 words)
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