While there is substantial research on the association between limited physical activity and obesity, new research confirms that being obese leads to reduced physical activity.
Although this relationship appears intuitive, prior studies had not assessed the link; BYU exercise science professor Larry Tucker, Ph.D., decided to look at the other side of the equation to determine if obesity leads to less activity.
The findings confirmed what many people have assumed for years.
“Most people talk about it as if it’s a cycle,” said Tucker, senior author on a study appearing online ahead of print in the journal Obesity.
“Half of the cycle has been studied almost without limit. This is the first study of its kind, in many ways, looking at obesity leading to decreases in physical activity over time.”
To study this reciprocal effect objectively, the researchers attached an accelerometer to more than 250 participants.
Accelerometers measure actual movement and intensity of activity. Previous studies have relied on less-dependable self-reported data.
“Roughly 35 percent of the population reports that they’re regularly active,” Tucker said.
“When you actually put an accelerometer on adults and follow them for many days, only about 5 to 7 percent are actually regularly active. We used an objective measure so we could determine genuine movement, not just wishful thinking.”
For the study, 254 female participants — 124 of whom were considered obese — were instructed to wear the accelerometer for seven consecutive days at the beginning of the study, and then again for an additional week 20 months later, at the end of the study.
Researchers discovered that on average, physical activity in obese participants dropped by 8 percent over the course of 20 months. This is equivalent to decreasing moderate to vigorous physical activity by 28 minutes per week.
In contrast, non-obese women demonstrated essentially no change in the amount of physical activity they were participating in weekly.
Researchers admit they were not surprised with the findings. However, investigators say the study does provide more understanding into how the cycle works and how it can be stopped.
Experts say the study offers additional insight into the measurement methods researchers use and how self-reporting can yield inaccurate results.
“It’s not rocket science, and it’s very logical,” Tucker said. “It just hasn’t been studied using high quality measurement methods and with a large sample size. This provides scientists with more ammunition to understand how inactivity leads to weight gain and weight gain leads to less activity. This cycle, or spiral, is probably continuous over decades of life.”
Source: Brigham Young University