科学家列出肥胖十大诱因

“少吃点，多运动”--这一直是肥胖者的减肥“座右铭”。但现在看来，所有的努力都可能白费了。

科学家们说，另有十条原因可以解释人们为什么不停的变胖。他们说，体重增加与睡眠习惯、中央供暖、药物、甚至某些污染物都有关。

针对肥胖问题，健康学家们一直强调饮食和运动，还有坚强的毅力。

然而，美国和加拿大一些名牌大学的科学家们说，以下这些因素也一定要考虑在内。

缺乏睡眠在一定程度上会导致肥胖。近几年，人们晚上的平均睡眠从9个小时下降到了7个小时。

缺乏睡眠会改变体内控制食物摄取和体脂肪的激素水平，增加饥饿感，促进食欲。

如果天气太热或太冷，体内热量的燃烧会使人体降温或升温。但如果温度适当，体内的热量则会转化为脂肪。

吃β-受体阻滞药控制血压的人体重常会增加3磅。此外，研究表明，服用口服避孕药的女性体重会增加11磅。

自然力量也是个因素。人的体型一部分由遗传因素决定。肥胖者往往会找一个和自己体型差不多的配偶，这样，他们的孩子肥胖的可能性就较大。

研究人员们说，如今污染物的使用越来越多。杀虫剂和塑料中所含的人造化学物质会影响我们体内的激素水平，从而导致肥胖。

母亲的年龄和婴儿出生时的体重也很重要。年龄偏大的女性生出肥胖孩子的几率较大，出生时体重不足的婴儿今后变肥胖的可能性也较大。

此外，随着我们年龄的增长，体重也会增加。最后一点，戒烟也会使体重增加。

耶鲁大学、康奈尔大学和约翰斯·霍普金斯大学的科学家们说，只有一些间接证据表明不健康的饮食和缺乏运动是肥胖的主要诱因。

睡眠--睡眠太少使胃口大增

药物--很多现代药物会导致体重增加<

母亲的年龄--年龄偏大的女性易生出肥胖的孩子

择偶--肥胖者之间容易结为伴侣，这会导致他们的孩子肥胖

供暖和空调--舒适的温度会阻碍体内脂肪的燃烧

基因--体型一部分由遗传因素决定

戒烟--尼古丁能抑制食欲

人造化学物质--有些化学物质会影响体内控制脂肪水平的激素

出生时的体重--体重不足的婴儿变肥胖的可能性较大

年龄增长--体重随着年龄的增长而增加

Eat less and exercise more - it has long been the mantra for shedding those extra pounds. But now it seems that all the hard work may have been in vain.

Scientists say there are ten other reasons why people just keep getting bigger. They claim that sleeping habits, central heating, medicines and even some pollutants can play a role in weight gain.

Traditionally, health practitioners have focused on diet and exercise - and a large dose of willpower - to treat the problem.

However the scientists from top U.S. and Canadian universities say that these other factors must be considered.

Lack of sleep could be partly to blame. In recent years, the average night's sleep has dropped from nine hours to just seven.

Sleep deprivation alters levels of the hormones that regulate food intake and body fat and increase hunger and appetite.

If it is too hot or too cold, we burn calories to cool down or heat up. But if the temperature is just right, the calories may be turned into body fat instead.

Those who take beta-blockers to control their blood pressure can often put on 3lb. Similarly, studies have shown that going on the Pill can add 11lb to a woman's weight.

Mother Nature may also be to blame, with our body shape being partly inherited. The overweight are also more likely to settle with partners of a similar size, and their children are more likely to be obese.

And the use of pollutants is on the rise, say the researchers. The manmade chemicals in pesticides and plastics can interfere with our hormones and lead to weight gain.

Your mother's age and your weight at birth are also important, with older women more likely to have obese children and underweight babies having a bigger chance of being obese in later life.

We also tend to put on weight as we get older. Finally, giving up smoking can also help pile on the pounds.

The scientists from Yale, Cornell and Johns Hopkins said there was only 'circumstantial' evidence supporting poor diet and lack of exercise as the main causes of obesity.

Sleep - Too little increases appetite

Medicine - Many modern medicines lead to us putting on weight

Mother's age - Older women are more likely to have obese children

Choice of partner - Overweight people tend to pair with each other - and have overweight children

Heating and air conditioning - 'Comfortable' temperatures stop us from burning off fat

Genes - Body shape may be partly inherited

Giving up smoking - Nicotine suppresses the appetite

Manmade chemicals - Some chemicals interfere with hormones that keep fat levels low

Weight at birth - Underweight babies have a bigger risk of obesity

Getting older - Weight tends to increase with age