Tracking the cultures over time, the researchers noted the development of lipid droplets in both the test and control groups of cells. However, after just two weeks of consistent stretching, the test group developed significantly more and larger lipid droplets. By the time the cells reached maturity, the cultures that received mechanical stretching had developed fifty percent more fat than the control culture.
They were, in effect, half-again fatter.
According to Prof. Gefen, this is the first study that looks at fat cells as they develop, taking into account the impact of sustained mechanical loading on cell differentiation. "There are various ways that cells can sense mechanical loading," he explains, which helps them to measure their environment and triggers various chemical processes. "It appears that long periods of static mechanical loading and stretching, due to the weight of the body when sitting or lying, has an impact on increasing lipid production."
Counting more than calories
These findings indicate that we need to take our cells' mechanical environment into account as well as pay attention to calories consumed and burned, believes Prof. Gefen. Although there are extreme cases, such as people confined to wheelchairs or beds due to medical conditions, many of us live a too sedentary lifestyle, spending most of the day behind a desk. Even somebody with healthy diet and exercise habits will be negatively impacted by long periods of inactivity.
Next, Prof. Gefen and his fellow researchers will be investigating how long a period of time a person can sit or lie down without the mechanical load becoming a factor in fat production. But in the meantime, it certainly can't hurt to get up and take an occasional stroll, he suggests.
|Contact: George Hunka|
American Friends of Tel Aviv University