Sleep-Deprived Teens Eat More Fat, Study Finds

Teens who sleep less than eight hours a night are more likely to eat a high-fat diet that puts them at risk for obesity and the many health problems connected with it, new research shows. The study, published in the Sept. 1 issue of the journal Sleep, found that these sleep-deprived teens consumed 2.2 percent more calories from fat, and ate more snacks than those who slept eight hours or more a night. They also ate more total calories. "There's been a lot of research over the last five years implicating insufficient sleep with obesity," said study author Dr. Susan Redline, of Brigham and Women's Hospital and Beth Israel Deaconess Medical Center in Boston.

"Some experimental studies on sleep deprivation in controlled laboratory environments show a craving for fatty foods among the participants" who got less sleep, she said. Redline, a professor of medicine with the school's division of sleep medicine, said sleep-deprived teens may suffer from metabolic disturbances that have been linked to obesity and insulin resistance in other research with shift workers whose sleep was also irregular. Metabolism is the body's process for turning calories into energy. Lack of sleep can affect metabolism by changing the level of appetite-regulating hormones like leptin and ghrelin, setting the stage for poor eating habits, Redline explained.

In addition to being a possible cause of metabolic problems, fewer hours of sleep provided teens with "more opportunities to eat," Redline said. Teens need about nine hours of sleep every night to feel rested and alert the next day, but few teens get that amount, experts said. "I almost never see anyone who is sleeping more than seven hours a night," said Dr. Paula Elbirt, an associate professor of pediatrics and adolescent medicine at Mount Sinai Medical Center in New York City. Insufficient sleep among teens is "the rule, not the exception," she said. Elbirt said the "adolescent lifestyle" encourages teens to stay up late.

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Short-Term Overeating Could Make Long-Term Weight Loss Tougher

If you think a few weeks of slothful behavior and caloric overindulgence can be easily worked off at the gym, think again. New Swedish research suggests that just a month's worth of unhealthy living changes physiology, making piled-on fat even harder to lose. "A short period of [over-eating] can have later long-term effects," said study co-author Dr. Torbjorn Lindstrom, an associate professor in the department of medical and health sciences within the faculty of health sciences at Linkoping University. "Based on this, it can be recommended to avoid very high food-intake that might occur during shorter periods in normal life."

Lindstrom and his colleagues report their findings in the current issue of Nutrition & Metabolism. They focused on 18 normal-weight healthy participants, averaging 26 years of age. For one month, all 18 were placed on a restricted physical activity regimen that involved the equivalent of no more than 5,000 steps per day. Five thousand steps, the team noted, is the threshold for a "sedentary" lifestyle, whereas a "physically active" lifestyle involved 10,000 steps or more. In addition, participants embarked on diets involving a 70 percent jump in daily caloric intake mainly from fast food amounting to about 5,750 calories ingested per day. The research also included a comparison group who did not change their diet/activity.

By the end of the month, the feasting group gained an average of 14 pounds. Their fat mass, specifically, was found to have gone up from about 20 percent of total body weight, to nearly 24 percent after the month-long intervention. Participants lost most of that new weight over the ensuing six months. However, one year after the study's end, participants still registered a noticeable gain in fat mass compared with their pre-study status. This fat stuck around despite the fact that the participants had returned to their lower-calorie pre-study diet and more active routines. Two-and-a-half years after the study, fat mass gains were even greater, registering just under 7 pounds on average, the researchers found. There was no such long-term change among the control group who had stuck to their usual diet.

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Cholesterol Levels Fluctuate With Menstrual Cycle

Women's cholesterol levels vary throughout their menstrual cycle as their levels of estrogen rise and fall, a new study reveals. This means that to get a clear picture of a woman's cholesterol levels, doctors may need to take readings over several months before deciding whether the patient needs to have her levels lowered, the researchers noted. "Doctors who are looking at women high cholesterol have to take into account the phase of the menstrual cycle they are at when they take the measurement," said study co-author Enrique F. Schisterman, chief of the Epidemiology Branch at the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

"Practically, it's easier to recognize the beginning of a cycle," he said. "So if you do it consistently at the beginning of the cycle then you will get consistent measures over time." The report is published in the current online edition of the Journal of Clinical Endocrinology and Metabolism.For the study, Schisterman's group compared levels of estrogen with cholesterol and triglyceride levels in 259 healthy women, aged 18 to 44. Most of the women, had 14 or more measurements taken over two menstrual cycles. The women also charted the phases of their cycles using at-home fertility monitors that detect hormone levels indicating ovulation. Most of the women were physically active and did not smoke.

Only 5 percent had cholesterol levels higher than 200 mg/dL, which is borderline high-risk for heart disease. But, cholesterol levels among 19.7 percent of the women reached 200 mg/dL at least once. To make cholesterol readings more consistent and reliable, measurements should be taken at the same time each month for a couple of cycles, Schisterman added. "Practically, it's easier to recognize the beginning of a cycle," he said. "So if you do it consistently at the beginning of the cycle then you will get consistent measures over time."The report is published in the current online edition of the Journal of Clinical Endocrinology and Metabolism.

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