Outlook: Obesity Epidemic

FEBRUARY 01, 2009

Elderly Lose Muscle Mass When Dieting Without Exercise

A group of sedentary and overweight older individuals placed on a 4-month exercise program not only became more fit, they burned off more fat, compared with those who dieted but did not exercise, according to a study published recently in the Journal of Applied Physiology.

Researchers at the University of Pittsburgh studied a group of 64 participants aged 60 to 75 who were either overweight or obese; all were sedentary at the outset of the study. They were divided into 3 groups: exercise only, diet only, and exercise plus diet. The diet-only group's weight loss resulted from a loss of both muscle and fat, and those who dieted without exercising lost more lean muscle, compared with those who exercised. When weight loss was combined with exercise, however, it nearly completely prevented the loss of lean muscle mass.

The exercise plus diet group also proved to be most efficient at the exercise task (either walking on a treadmill or riding a stationary bicycle) at the end of the experiment and, like the exercise-only group, drew more on fat stores as an energy source.

Kids Prefer "Texting" Their Food, Exercise Diaries

A study of children aged 5 to 13 found that those who kept track of their daily food intake, exercise, and screen time by using text messaging were twice as likely to keep such records when compared with those using old-fashioned types of paper-and-pencil diaries.

Previous studies have shown that dieters who keep records are more likely to lose weight and keep it off. For this study, children and parents participated in 3 weekly group education sessions aimed at encouraging them to increase physical activity and decrease screen time and consumption of sugar-sweetened beverages. They were asked to record their behaviors via short-message service or paper diaries, alongside a no-monitoring control group.

Researchers at the University of North Carolina at Chapel Hill then compared the participants' adherence to self-monitoring and found that those who used text messaging had significantly greater adherence. The researchers note that although the approach "may be a useful tool for self-monitoring healthful behaviors in children," further study is needed. The implications do suggest that novel technologies may play a role in improving health, according to the investigators. The findings were published in the November/December 2008 issue of the Journal of Nutrition Education and Behavior.

Large Waistline Risky for All

A large waistline can almost double the risk of dying prematurely, even with a body mass index (BMI) in the normal range, according to findings from a recent study of 350,000 individuals across Europe.

Comparing participants with the same BMI, researchers found the risk of premature death increased in a linear fashion as the waist circumference increased. Each 5-cm increase in waist circumference increased the mortality risk by 17% in men and 13% in women. The ratio of waist to hips was revealed as an important indicator of health in the study.

The risk of premature death was approximately double for patients with a larger waist (>120 cm or 47.2 in for men and >100 cm or 39.4 in for women), compared with those individuals with a smaller waist (<80 cm or 31.5 in for men and <65 cm or 25.6 in for women). Although the main new finding of this study is that waist size increases the risk of premature death independent of BMI, the study does support earlier findings showing that a higher BMI is significantly related to mortality.

The new research forms part of the European Prospective Investigation into Cancer and Nutrition (EPIC), one of the largest long-term prospective studies in the world.

"The good news is that you don't need an expensive test and wait for ages for the result to assess this aspect of your health—it costs virtually nothing to measure your waist and hip size," said Professor Elio Riboli, MD, MPH, the European coordinator of the EPIC study.

The findings were published in the November 13, 2008, issue of the New England Journal of Medicine.

CDC Issues New Guidelines for Physical Activity

Recently released guidelines from the Centers for Disease Control and Prevention say that a minimum of 150 minutes of moderate-intensity physical activity per week, such as brisk walking, or 75 minutes per week at a level of vigorous intensity, is necessary to produce substantial health benefits in adults.

The "2008 Physical Activity Guidelines for Americans" marks the first time the federal government has issued a comprehensive set of guidelines on physical activity, noted US Department of Health and Human Services Secretary Michael Leavitt. The guidelines are intended to be a primary source of information for health professionals and the public and are based on an extensive review of the scientific data on physical activity published since the 1996 Surgeon General's Report on Physical Activity and Health.

The full set of guidelines for both children and adults can be accessed at www.health.gov/PAGuidelines/.