Thursday, April 19, 2012

exercise and food stimuli - how the brain responds

over a year ago, i gave a talk at the first Lifestyles Management meeting in Las Vegas. my presentation was on the science of weight loss via exercise. the results of my research were dim, esp for those who were wanting to believe the calories out part of the formula. of course, not that people don't lose weight via exercise, it's just that it takes a near monumental effort of intensity and consistency to do so; and long term success, tho dependent on some exercise, really comes from dietary changes mostly in the form of caloric restriction.

at the time, most of the research was pointing toward the hormonal effects of exercise and of eating on neurochemical signals to eat or stop eating. obesity alters many of our body's responses - insulin resistance is a common feature most of us have heard about - and may indeed alter the brain's response to hormones such as leptin and others that affect appetite. this NY Times piece discusses the latest in functional MRI research on the brain's response to exercise when enticed with pictures of foods. turns out some folks respond by getting ravenous, others with a blunted hunger and appetite. in fact, one study showed that lean, fit, young people were more apt to have the reduced appetite after exercise while less fit overweight people were hungrier after exercise. all, however, seemed to desire food more after a period (one hr) of quiet sitting. hmmm, there's a message there somewhere. could it be sitting is appetite stimulating? or that being fit and lean lends itself to being....fit and lean?

another study found that some exercisers who had weight to lose lost it as expected while others did not respond accordingly. the non-responders also had more brain temptation for food after exercise than did the responders. what's this tell you? that some are better designed to lose weight, by any means, than others. duh.

so, what do I think?

well i still hold that exercise should be done for health and function. eating proper foods in terms of amounts and types and even times is for health and function; taste and enjoyment really have nothing to do with amount. in fact, as a friend of mine noted when she got serious about weight loss, the first cookie tastes as good as the third; stop at the first. it's why fancy cuisine, esp continental style cooking, does not overload you with any one food, but spacing the dishes properly, and sizing them sanely, satisfies in ways that a giant serving of pasta and garlic bread do not: deliciously, without stomach upset that night or the next morning.

on that note, what i took from the article is that exercise is good for you and that some people will have to be more attentive to what they eat to lose weight. the other thing i took from it is that science is still trying to find out why so they can come up with a pill to substitute for the hard work that has to be done to live healthfully. i agree with the first sentence and abhor the second. even if we find a magic bullet, wouldn't it be a shame if people all over could control weight while being sedentary? they'd never get to appreciate who and what they are as human machines.