Vitamin Zzzzzzz D ieters lose more fat and less muscle if they get enough sleep, says a small, pro-vocative new study. Researchers put 10 sedentary overweight middle-aged men and women on a lower-calorie diet. For two weeks, roughly half were allowed to sleep for 5½ hours a night, while the other half got to sleep for 8½ hours. After a three-month break, they switched. Sleep had no impact on how many pounds the participants lost. But when they were sleep-deprived, they lost 55 percent less fat and 60 percent more lean body mass (mostly muscle) than when they were allowed to sleep for 8½ hours a night. The participants also had a lower metabolic rate, felt more hungry, and had higher ghrelin levels when they were sleep-deprived. Ghrelin is a hormone that stimulates ap-petite. What to do: Shoot for eight hours of sleep each night. Although these results need to be confi rmed, other studies have found that people who sleep less are more likely to be overweight or obese. Ann. Intern.Med. 153: 435, 2010. PREVENTING PARKINSON’S Exercise may lower your risk of Parkin-son’s disease, the second most common cause of dementia among older people. In the mid-1990s, researchers askedmore than 200,000 middle-aged and older par-ticipants in the NIH-AARP Diet and Health Study how often they exercised during four periods of their lives (ages 15 to 18, 19 to 29, 35 to 39, and in the past 10 years). A decade later, 767 of the participants had been diagnosed with Parkinson’s dis-ease. Participants who had reported more than seven hours a week of moderate or vigorous activity at ages 35 to 39 or in the recent decade were 35 to 40 percent less likely to be diagnosed with the illness than those who rarely or never did mod-erate to vigorous activity. Lighter activity and exercise at younger ages weren’t linked to Parkinson’s. What to do: It’s possible that the less-active people in the study exercised less because the disease had already begun before they entered the study. If that were the case, exercise wouldn’t lower the risk of Parkinson’s. Of course, there are plenty of other reasons to exercise. But you can’t just stroll, bowl, slow dance, or do light housework. Those are light activities. Try brisk walking, tennis, biking, swimming, or not-so-slow dancing. Neurology 75: 341, 2010. Green Leafies vs. Diabetes Green leafy vegetables like spinach and kale may lower the risk of Type 2 diabetes. British researchers pooled the results of four studies that followed a total of 177,000 people (mostly women) for 5 to 23 years. Overall, those who averaged 1¹∕³ serv-ings of green leafy vegetables a day were 14 percent less likely to be diagnosed with diabetes than those who averaged only one serving every five days. What to do: It’s not clear if greens prevent diabetes or if it’s just that healthy people eat more greens and have a lower risk of diabetes. Either way, why not have a spinach salad tonight? BMJ 341: c4229, 2010. Whole Grains & Belly Fat People who eatmore whole grains have less visceral belly fat, the kind that’s linked to a higher risk of heart disease and diabetes. Scientists measured both subcutaneous (below-the-skin) fat and the deeper layer of visceral fat in more than 2,800 middle-aged participants in the Framingham Heart Study. People who reported eating at least three servings of whole grains a day had 10 percent less visceral fat than those who said they ate less than a serving per week. However, whole grains were not linked to less visceral fat in people who also consumed at least four servings of refined grains a day.Whole-grain eaters also had smaller waist sizes than refined-grain eat-ers. What to do: Replace refi ned grains with whole grains. The Framingham partici-pants got most of their whole grains from bread, ready-to-eat breakfast cereals, oatmeal, popcorn, and brown rice. Pasta, English muffi ns, white bread, pizza, and white rice were the major sources of refined grains. Am. J. Clin. Nutr. doi: 10.3945/ajcn.2009.29106. 8 NUTRITION A C TION HE ALTHLE T T E R ■NOV EMBER 2 0 10 Photo:©Monkey Business/fotolia.com.
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