Activitystat

Several recently reported research findings suggest that there’s a setting in the brain that determines how active each of us is going to be or wants to be.

The EarlyBird project at the Peninsula Medical School in Devon, led by Professor Terence Wilkin, is following the progress of a group of 300 British children from age 5 to age 16, monitoring their activity levels and metabolism as they grow up. Although children vary a lot in how active they are (Prof Wilkin’s group found a four-fold variation between children in their test subjects), each child is consistent in how active he or she is day-to-day. This doesn’t depend on how much organised physical activity there is at school, or on daily routine, socio-economic status or background. If children are more active at school, they’re less so at home and vice versa. In particular, confounding a popular view, how much TV a child watches didn’t affect how much exercise he or she takes. One implication is that you can’t necessarily assume that obese children are that way because they’re sedentary.

Professor Wilkin coined activitystat for the mechanism in the brain — probably in the hypothalamus — that sets energy expenditure and hence physical activity for an individual. The word comes from activity plus thermostat, a parallel formation to appestat, a known brain mechanism that controls appetite. Activitystat is first recorded in print in The Journal of Diabetes Nursing in 2005.

This activitystat, like a thermostat, will adjust your energy expenditure down when it thinks you have been too active, and up when you haven’t been active enough.

Guardian, 7 Aug. 2007

The activitystat hypothesis emerged after trials suggested that no matter how much or how little exercise children were offered, they found their own level. “Like horses brought to water,” says Professor Wilkin, “children with low-activity settings may simply not participate.”

Times, 23 Apr. 2007