Many Unusual Environmental Factors Contribute to Obesity
Researchers are finding that all cases of obesity are not as simple as calories in versus calories out. There are many factors that affect the body’s metabolic processes, which can result in weight gain or an inability to effectively lose weight. Researchers from the University of Turin in Italy suggest that sleep habits and indoor climate control may play a role.
Chronic Sleep Loss and Indoor Home Temperature May Affect Obesity
Dr. Simona Bo and colleagues investigated certain lifestyle habits in a cohort of almost 1300 middle-aged adults. None had preexisting obesity at baseline, but at the end of six years, 103 had significantly higher body mass index and waist circumference.
Diet of course was the most obvious factor involved in the weight gain. The more often the people at out at restaurants each week, the greater the likelihood they would become obese. Also, those with less fiber intake and greater saturated fat intake were also more likely to gain weight.
Lower amounts of physical activity also affected obesity rates, as expected.
The researchers also looked at sleeping habits. For each hour of sleep that a person typically got each day, there was an associated 30% decline in the risk of becoming obese. This held true even when factors such as physical activity and television watching were taken into account.
Chronic sleep loss (defined as sleeping less than six hours a night) can contribute to weight gain in many ways.
“When people are sleep-deprived,” explains clinical psychologist Michael Breus, PhD, a diplomate of the American Board of Sleep Medicine and a fellow of The American Academy of Sleep Medicine. “Metabolism will slow down, appetite will increase, and certain hormones are affected.”
But the most interesting finding of the study was the link between home temperature settings and weight gain. Compared to people who kept their homes no warmer than 68 degrees Fahrenheit in the fall and winter, those who kept their homes warmer were twice as likely to become obese.
The theory, according to Dr. David B. Allison, director of the Nutrition Obesity Research Center at the University of Alabama at Birmingham, is that the body burns more calories when it has to work to maintain a stable temperature. Dr. Allison was not involved with the Italian study, but notes that using less air conditioning in the summer may also have the same effect.
Researchers and public-health advocates should be "open-minded" about the possible contributors to obesity. "No one factor is going to explain the obesity problem," concluded Dr. Allison.
SOURCE: International Journal of Obesity, online February 1, 2011.