Archive for Wednesday, April 19, 2006

Studies link decrease in sleep with weight gain

April 19, 2006


Q: Is it true that lack of sleep increases your risk of becoming obese?

A: Mary Higgins, K-State Extension specialists in nutrition education, offers this research: In a 2005 Canadian study of 740 normal-weight adult men and women, those who slept the least (five to six hours) weighed more than those who slept for seven to eight hours each night. A 2004 study found that people who sleep just two to four hours a night were 73 percent more likely to be obese than people who sleep seven to eight hours. Another 2004 study, conducted in Wisconsin, found that three out of four people average less than eight hours of sleep. Body weights increased as sleep duration decreased. People who averaged five hours of sleep weighed slightly more (3 to 4 percent) than those who slept an average eight hours a night.

The sleep-body weight connection may result from changes in the amount of a hormone known as leptin. Higher levels of leptin help control body weight (leptin decreases hunger and appetite, and increases energy used). Decreased leptin or not responding to its effects promotes weight gain.

People who sleep less seem to have less circulating leptin. In the Canadian study, 88 percent of the people who slept just five to six hours had lower leptin levels than those who slept longer. Similarly, a small experiment in 2004 found that sleep deprivation (four hours per night) decreased leptin levels and increased hunger and appetite in healthy young men. The 2004 Wisconsin study also found that leptin levels were decreased in people who reported that they consistently slept for five hours, compared with those who slept for eight hours.

Every little bit of extra sleep may help. A study reported in 2005 found that an extra 20 minutes of sleep per night was associated with a lower body weight. Americans report sleeping almost two hours less per night than they did 40 years ago. Even children often do not get enough sleep.

Thus, chronic sleep restriction may contribute to obesity. Your prescription for better health may involve getting a longer night's sleep more often.

Q: How much is drinking soda associated with weight gain?

A: I'd like to thank Mary Higgins for this information, too. Here's what she shared:

Obviously, reducing sugar-added beverages, overall intake of sugary foods and excess calories from any source helps prevent excessive weight gain.

For example, a two-year study of the eating habits of 10,000 U.S. children ages 9 to 14 years found that consumption of sugar-added beverages may contribute to weight gain, because drinking sugar-added beverages encourages a higher total calorie intake. Girls who drank sugar-added beverages tended to be the heaviest.

Drinking diet soda may or may not help protect against weight gain. Both lower and higher body weights are seen among people who drink diet sodas. Why would there be an increase in weight? Nobody is sure yet. Diet soda probably does not cause weight gain, but heavier people may choose diet sodas to help lose weight, or to prevent further weight gain. Use of diet soft drinks might be part of other eating habits and lifestyle choices that lead to weight gain.

Studies that linked sugar-free carbonated beverages to lower body weights include an experiment reported in 2002. Overweight adults given two different diets, in the amounts that they wanted, were compared after 10 weeks. The group fed a high-sucrose diet, mostly as sugar-sweetened beverages, increased their calorie intake, body weight and fat mass. The group that received artificially sweetened foods and beverages decreased their calorie intake, body weight and fat mass.

A 2001 survey study with 12-year-olds found that the chances of becoming obese increased by 1.6 times for each extra serving (one can) of sugar-sweetened drink consumed daily. By comparison, increasing the amount of diet soda consumed was associated with just half the risk for developing obesity.

Other studies have reported that drinking diet soda is linked to weight gain. The risk of becoming overweight was 33 percent for people who drank one to two cans of regular soft drinks, 55 percent for those who drank one to two cans of diet soft drinks, and 67 percent for those who drank one can of regular and one can of diet soda, according to a 2005 preliminary report of an eight-year study of 622 normal-weight people.

Another team looked at a nationally representative sample of U.S. children and teens. Increased body weight was weakly associated with an increased intake of diet carbonated beverages.

In the large study of 10,000 children mentioned previously, diet soda intakes were not associated with higher total energy intakes.

For boys, intakes of both sugar-added beverages and of diet soda were significantly associated with excess weight gain. The link between gaining weight and increasing their sugar-added beverage intake from one year to the next was strong, while the link between weight gain and increasing diet soda intakes was weak. The heavier boys drank both diet and regular soda. The overweight boys drank one serving per day of diet soda, while the normal-weight boys drank just one-third of one serving. Both groups drank about one-half serving a day of regular soda.

Therefore, when choosing beverages, the best advice at this time is to drink plenty of water and get enough low-fat or fat free milk. Limit sugar-sweetened drinks, including juices, and diet soft drinks too.


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