Why To Exercise Today: Impending Fatty Holiday Food

It's not just that we'll likely be eating more in the coming holiday season, it's what we'll likely be eating: Roast beef. Buttery mashed potatoes. Pies. All washed down with egg nog. So today's Phys Ed column on the Well blog of nytimes.com offers particular incentive to get moving: New findings that suggest that exercise helps offset the weight gain and heart harm of high-fat diets.

It describes recent studies of 100,000 runners and almost 40,000 walkers that found that exercisers who ate high-fat diets gained less weight than their high-fat-eating counterparts who did not exercise. And how about these rats? In another recent study:

The rats were given free access to fatty foods for 12 weeks, by which time they all had become rotund and developed metabolic syndrome, a constellation of unhealthy conditions that includes insulin resistance, poor cholesterol levels and high blood pressure. Then the researchers divided the animals into several groups, with some remaining on the high-fat diet but running every day, while others were switched to a standard kibble, and still others changed nothing. This new program also lasted 12 weeks.

By the end of that time, the rats that ran had managed to “reverse almost all the atherosclerotic risk factors linked to obesity,” the researchers found, even though they remained on the high-fat diet. They also had stopped gaining weight. The rats that had been switched to a standard diet but didn’t run improved their metabolic profiles, too, but not as much as the running rats. The researchers speculate that exercise activates certain metabolic pathways that undo the damage of a high-fat diet, even if that diet continues.