Laying up for a solid night's sleep might not sound like the best recipe for weight loss, but loads of research has pointed to the importance of sufficient shut-eye to losing weight. And a small new study shows that not getting enough sleep might severely cut into people's ability to lose extra fat.

想减肥就要把觉睡好，这在减肥的人看来好像不是个好方案。但是，大量研究已经指出，充足的睡眠对减肥的很严重。下面有一个小型研究，展示了睡眠不足可能会严重影响人体消去多余脂肪的能力。

Researchers found that if dieters got a full night's rest, they more than doubled the amount of weight lost from fat reserves. So even though subjects lost about as much weight when they were sleep deprived as when they were well-rested, only about a quarter of the weight lost during the short sleep period was from fat. Tired-eyed dieters also reported feeling hungrier than they did when they had gotten enough sleep. Results of the study were published online October 4 in Annals of Internal Medicine.

研究人员发现如果节食的人晚上睡得好，减肥效果会好不止一倍。所以，尽管减肥的人在睡眠不足和睡眠充足时减掉的重量一样多，但是在睡眠不足时，减掉的重量中，仅仅只有1/4是脂肪。睡眠不足的节食者也说，他们感觉比睡眠充足的时候要饿。这项研究的结果发布在了10月4日的“内科年鉴”网络上。

"Cutting back on sleep, a behavior that is ubiquitous in modern society, appears to compromise efforts to lose fat," Plamen Penev, an assistant professor of medicine at the University of Chicago and study co-author, said in a prepared statement. Study subjects lost about 55 percent more fat when they got ample sleep at night.

在Chicago大学的医学助理教授，也是这篇研究的合著人Plamen Penev在一份事先准备好的的发言中说道：“当今社会，普遍认为减少睡眠是减掉脂肪的一个妥协方法。”但是在我们实验中志愿者，他们在获得充足的夜间睡眠时，脂肪多减了55%。

For the study, 10 overweight volunteers (ages 35 to 49 with a mean body-mass index of 27.4 kilograms) started a personalized diet plan that reduced calories (to an average of about 1,450 per day) but maintained a sedentary lifestyle. For two weeks, subjects reported to the lab to spend 8.5 hours a night in bed (with an average sleep time of about seven hours and 25 minutes), and during a second two-week period—either three months before or after the 8.5-hour nights—the same volunteers were allowed only 5.5 hours a night in bed (with an average sleep time of five hours and 14 minutes).

为了这项研究，对10个肥胖志愿者（年龄在35岁到49岁之间，平均体重指数是27.4千克）开展一项个体化节食计划，可以降低热量（平均每天降低1450卡），但要保持久坐的生活方式。有一个两周的时间，志愿者们每晚在床上8.5小时（有效的平均睡眠时间大约是7小时25分），另一个2周的观察期-可以在早于或晚于8.5小时测验的3个月之前或之后-还是这些志愿者，让他们每晚在床上5.5小时（平均有效睡眠时间是5小时14分）。

During both study sessions, the subjects lost about three kilograms each. Nearly half of that (1.4 kg) was from fat when the volunteers were sleeping long, but less than a fifth (0.6 kg) of the lost weight was from fat when they got less than six hours of sleep. The rest of the weight was fat-free body mass, which includes other components such as water or muscle, and is generally not the target of those seeking to lose weight.

在这两个实验中，志愿者们每人一共减掉大约3公斤体重：有接近一半（1.4千克）是在长睡眠阶段减掉的，仅有小于1/5（0.6千克）是在短睡眠阶段减掉的。其余减掉的重量来自去脂组织，例如包括水和肌肉，而它通常不是减肥者的目标。

Food cravings and metabolism are controlled in part by hormones, such as ghrelin, which stimulates hunger and lowers energy use. And when the study subjects were getting less than six hours of sleep a night, their ghrelin levels rose from 75 nanograms per liter to 84 ng per liter. Levels remained steady when subjects got plenty of rest. The volunteers were on the same tightly controlled low-calorie diet during both phases of the study, and the weight- and fat-loss difference between adequate sleep and too little sleep might otherwise be even more pronounced, the researchers behind the study speculated.

食欲和新陈代谢部分是由激素控制的，比如胃促生长素。它能刺激食欲、降低能量消耗。当志愿者在每晚睡眠少于6小时的情况下，他们的胃促生长素水平从75纳克/升，升高到84纳克/升，而在睡眠充足时胃促生长素的水平则保持稳定。研究人员认为，从另一方面看，由于志愿者是处于同等严格的低卡饮食控制下，所以充足睡眠和缺少睡眠对体重和脂肪消耗的影响就更显著了。

So despite any extra calories a person might burn while burning the midnight oil, losing sleep is hardly the best way to lose fat, this study suggests. "If your goal is to lose fat, skipping sleep is like poking sticks in your bicycle wheels," Penev said. "One should not ignore the way they sleep when going on a diet." Plenty of other research also suggests that getting enough sleep is also crucial for good long-term health in general.

所以，这个研究就是告诉大家，不管一个人在熬夜的时候消耗了多少热量，减少睡眠都不是减肥的最好方法。Penev说道：“如果为了减肥而不睡觉，就是在拖减肥的后腿”还说道“人们不应因减肥而不顾正确的睡眠习惯”，很多其他研究也表明，通常来说，保持充足的睡眠对人们长远的健康也是很重要的。