Embargoed news from Annals of Internal Medicine

New Study Shows Lack of Sleep Undermines Dietary Efforts to Lose Body Fat

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According to a new study being published in Annals of Internal Medicine, the flagship journal of the American College of Physicians, lack of sleep may hinder a dieter's ability to shed excess body fat.

Ten overweight but otherwise healthy adults on a moderate calorie-restricted diet were randomly assigned to sleep either 5.5 hours or 8.5 hours each night in a closed clinical research environment. After two weeks, researchers measured loss of fat and lean body mass. Compared to participants who slept 5.5 hours a night, the dieters that slept for 8.5 hours lost 56 percent more body fat. The dieters in the sleep restricted group had lost less fat and more lean body mass.

"These results highlight the importance of adequate sleep for maintenance of fat-free body mass when dieting to lose weight," said Plamen Penev, MD, PhD, Assistant Professor, Section of Endocrinology, at the University of Chicago and lead author of the study.

While measuring fat loss was the primary objective of the study, researchers also assessed other factors including levels of hormones that affect the appetite and weight. In addition, participants in both groups were asked to report how much hunger they experienced during the study.

"Among other hormonal effects, we found that sleep restriction caused an increase in ghrelin levels in the blood," said Dr. Penev. "Ghrelin is a hormone that has been shown to reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase glucose production in the body. This could explain why sleep-deprived participants also reported feeling hungrier during the study."

The researchers conclude that even short periods of sleep deprivation can undermine efforts to lose weight. When restricting calories, dieters should consider obtaining adequate amounts of sleep to ensure that they retain lean body mass and lose fat.

2. Gene Expression Test Could Help to Identify Patients with Coronary Artery Disease

Coronary angiography is considered the gold standard for detecting coronary artery disease, or CAD. Because angiography is expensive and invasive, noninvasive alternatives are needed. Scores are available that use clinical factors such as cholesterol levels, type of chest pain, and blood pressure to predict risk of CAD, but more accurate methods might be better able to identify whether patients need invasive testing. Researchers sought to determine if a previously developed gene test that gives a score based on the pattern of 23 genes associated with CAD could improve upon three existing risk scores in nondiabetic patients. Five hundred-twenty-six non-diabetic patients had their gene test score determined from a blood sample. Then, the patients underwent coronary angiography. The gene test modestly improved detection of CAD compared with the Diamond-Forrester method (a method taking into consideration type of chest pains and health history), but was not as helpful when more clinical information was available to the physician. The test was better able to identify patients who had CAD than those who did not. The author of an accompanying editorial cautions that scientists are developing genomic technologies faster than they can be tested and proven. She writes: "Rosenberg and colleagues' algorithm is an initial proof-of-concept for the potential use of genetic risk scores in the context of cardiovascular disease. Unfortunately, it does not fulfill the tough evidentiary standards that modern clinicians should demand."

3. HIV Patients Do Not Develop Cancer at Younger Age

Patients who have a weakened immune system because of HIV infection are more prone to experiencing a variety of infections and diseases, referred to as AIDS-defining illnesses. Several types of cancer are included in those illnesses. Patients infected with HIV also have an elevated risk for other cancers that are unrelated to HIV infection. It has been reported that HIV-infected individuals get cancer at a younger age than the rest of the population, suggesting that HIV accelerates physiologic aging. Researchers studied 212,055 patients enrolled in HIV/AIDS and cancer registry databases in the U.S. to compare ages at diagnosis for cancers unrelated to HIV infection. After adjusting for the ages of the populations at risk (adjustments are necessary because the proportion of older persons with AIDS is far smaller than the proportion of older people in the general population), they found that for most types of cancer, the age at diagnosis is similar in the AIDS and general populations. These findings refute the theory that AIDS accelerates the physiologic aging process.

4. Childhood Cancer Survivors at Highest Risk for Second Cancers Do Not Comply with Recommended Screening Guidelines

Survivors of childhood cancers are at risk for second malignancies during adulthood. Physicians recommend that survivors at average risk strictly adhere to the same cancer screening guidelines developed for the general population. However, due to intense treatment, some survivors are at a higher risk for developing certain types of cancer. The Children's Oncology Group guidelines recommend more aggressive surveillance and screening for survivors at high risk for breast, colorectal, or skin cancer. To determine how well average and high-risk childhood cancer survivors adhere to these guidelines, researchers surveyed 4,329 male and 4,018 female survivors of childhood cancer that were diagnosed between 1970 and 1986 about the receipt and timing of mammography, Pap smears, colonoscopy, or skin examination. The researchers found that while average risk female survivors were somewhat compliant with cervical and breast cancer guidelines for screening, surveillance for new cases of cancer was alarmingly low in survivors at the highest risk for colon, breast, or skin cancer. The researchers suggest that physicians need to educate childhood cancer survivors and their physicians about their risks for second cancers and associated screening recommendations.