Today’s NYTimes asks, “Is Sitting a Lethal Activity?” Only 2.4% of Americans over age 60 move around for at least 30 minutes per day. Our bodies are designed to be farmers, or hunter-gatherers, not desk-bound knowledge workers. In a study of people who were forced to overeat and prevented from exercising, some gained weight and some didn’t. Why?
“The people who didn’t gain weight were unconsciously moving around more,” Dr. Jensen says. They hadn’t started exercising more — that was prohibited by the study. Their bodies simply responded naturally by making more little movements than they had before the overfeeding began, like taking the stairs, trotting down the hall to the office water cooler, bustling about with chores at home or simply fidgeting. On average, the subjects who gained weight sat two hours more per day than those who hadn’t.
We know that dopamine controls movement and mood. People often eat to feel better. Sometimes they go for a walk/jog/run to feel better. Dance or make love or other pleasurable vigorous activity. We know that exercise elevates mode.
Did you know that obese people have lethargic dopamine receptors? The top left image shows the brain scan of a normal person eating. Next to it is the cooler, bluer scan of the obese person eating. Not as much excitement. See article.
The two hot images below them show that, overall, normal weight and obese people have similar brain metabolic activity. The big difference is whether eating lights up their pleasure center (dopamine receptors).
The bottom chart shows Body Mass Index (BMI) from low (skinny) on the left to high (fat) on the right. The number of dopamine receptors that are lit up by food PLUNGES the fatter you get. In terms of getting a dopamine boost, the more you eat, the less you get. Does fat lower dopamine receptors or the other way around? Could this be nature’s way of taking the fun out of eating? See this article from about a year ago.
The results support the notion that type 2 dopamine receptors (D2DR) — brain receptors that have been shown to play a key role in addiction — also play a key role in the rats’ heightened response to food. In fact, as the rats became obese, the levels of D2DR in the brain’s reward circuit decreased. This drop in D2DR is similar to that previously seen in humans addicted to drugs like cocaine or heroin.
We know that movement and non-verbal play lifts mood (increases dopamine). Isn’t it interesting to learn that using food to lift mood becomes a dull weapon the more we use it? This is the paradox that to get more energy, you need to spend more energy.
Nature can be harsh.