We’re entering a brutal time of the year for fitness.
Between Christmas hams (or, for families like my own, gigantic Chinese dinners) and the rich hor d’oeuvres and copious booze of New Year’s Eve—not to mention the fact that travel plans, trips to the mall, and the frigid weather in much of the country make it hard to get to the gym—many people are not going to be happy the first time they step on a scale in 2014.
A new study from researcher at the University of Bath, though, provides a strong argument for doing whatever you can to exercise this week—even if things are a lost cause from a weight-gain perspective.
The reuslts of the study, published in a paper entitled “Exercise counteracts the effects of short-term overfeeding and reduced physical activity independent of energy imbalance in healthy young men” which was published in the December 15th issue of The Journal of Physiology, suggests that when we talk about weight gain, we should pay attention to more than just the calories in/calories out formula that tends to dominate the discussion. Even if you know you’re going to gain a couple of pounds this week, there may be healthy and unhealthy ways to do so—and exercise could be the key to mitigating the damage.
Jean-Philippe Walhin, the paper’s lead author, said that, “When you read the literature, a lot of the time benefits from exercise are hard to isolate.” The fact that exercise causes weight loss leads to methodological difficulties, making it tricky for researcher to interpret the results of their studies. “If exercise leads to weight loss, it’s hard to tell whether it’s the weight loss alone or the exercise that’s actually benefiting the health of the participant,” he explained.
Walhin and his colleagues got around this potential confusion with their experiment’s setup. They took 26 active men, 25 years old on average, and split them into two groups. Both groups were overfed for a week: 14 of the subjects ate 50% more calories than their baseline diet, while the other 12 ate 75% more than their baseline diet, but also ran on a treadmill for 45 minutes a day (otherwise, all 26 were instructed to engage in very little exercise).
The researchers didn’t just weigh the participants, but recorded a wide variety of other health measures as well. The results: overfeeding and under-activity “induced a reduction in insulin sensitivity in healthy individuals, with significantly altered expression patterns of several key genes and proteins within adipose tissue that are involved in nutritional homeostasis, metabolism and insulin action,” they wrote. Phrased more bluntly, lying around and eating too much messes up your body. No surprise there. But—and this is key—“the inclusion of a daily vigorous-intensity exercise bout attenuated or even prevented these changes independent of any net effect on energy imbalance.” In other words, even if Frank and Tom gain the same amount of weight, Frank’s body may be handling things much better if he’s exercising and Tom’s not. (The folks in the exercise group did gain less weight, but Walhin said this result wasn’t statistically significant and isn’t noteworthy because it can be explained by other factors.)
“This study suggests that regular exercise has positive health benefits, even in the face of overfeeding,” wrote Todd Hagobian, a kinesiology researcher at California Polytechnic State University who was not involved in the study.
The study does have a few limitations, however. All the subjects were in good shape before it began, and all exercised regularly. In addition, the exercise group ran for 45 minutes a day—a longer and more intense period of exercise than most Americans undertake. So there’s a chance, as Walhin acknowledged, that the results could be due to the intensity of the exercise or that the prior fitness of the participants could have factored into the results. “We can’t alway say whether different types of exercise or in a different population, whether we would see the same thing or not, really,” he explained.
“The issue is that the few human studies that have examined the impact of overfeeding plus exercise have used relatively healthy, fit individuals,” wrote Hagobian. “Their metabolic and health responses to the overfeeding plus exercise treatment may be much different than a clinical, at-risk population (obese).”
But Walhin defended the use of healthy volunteers. They were chosen because “they don’t have an underlying condition like diabetes or something like that. So we can really see from a healthy point of view the first things to go wrong, and that was the reason why we chose that population. And obviously some of the work would need to be validated in different populations.” That is, tracking the effects of overeating on someone who already had health issues would have been all the more daunting, and could have told less clear of a story. As for the intensity of the exercise, Walhin said, “I think we could presume that if people went for a long walk or something like that on a daily basis, hopefully we’d see the same benefits.”
Walhin’s advice for everyday people simply trying to minimize the nutritional ravages of the holiday season was simple. “I would advise in any case, people to at least try to be active, even if it’s just for a bout every day, rather than actually just sitting, watching TV and drinking and eating too much,” he said. “So I think that any physical activity would be better than nothing.”
Walhin also emphasized just how much more research needs to be done in this area.
“There’s probably a bit more than just calories in, calories out,” he said. “Even though we’re trying to understand all the mechanisms and explain why that is, it’s still quite tricky for us to understand exactly what’s going on, and that’s why we’re trying to do this kind of research.”