Audrey Bergouignan, PhD, isn’t looking for people with obesity to start running marathons. She just wants them to walk across the room.
Bergouignan, an assistant professor of endocrinology, metabolism, and diabetes at the University of Colorado School of Medicine and director of research at the French National Center for Scientific Research, specializes in research on the effects of sedentary behavior and physical activity on obesity. She recently published a review paper in the journal Obesity Reviews that analyzes years of research on the topic, looking particularly at data on the benefits of light physical activity such as walking, gardening, and taking the stairs.
“If you take people who are very sedentary and are overweight or obese and you ask them to go on the treadmill for 30 or 40 minutes, they may be exhausted,” Bergouignan says. “But if you focus on light intensity — you put physical activity at the center of their daily life and just get them to move — now they may be able to sustain this new active lifestyle.”
Light physical activity seems to have the added benefit of not triggering a compensatory response, Bergouignan says — the feeling that “I worked out today, so I can eat an extra cookie,” which can completely negate the benefits of the exercise.
Combating exercise misinformation
Bergouignan says she wrote the review paper in large part because of the current debate in the scientific community on the effects of physical activity on weight regulation, as well as buzzy headlines in major newspapers and magazines claiming that exercise has no benefits when it comes to controlling weight.
“I’m very frustrated by that,” she says. “People see that, and the ones who already didn’t want to exercise say, ‘Why would I do this? It’s useless anyway.’ I think as scientists and researchers, we have a responsibility in terms of public health.”
That’s why she set out to paint a more complete picture with her review paper, looking at everything from historical changes in physical activity patterns from ancient times to the present (spoiler alert: modern man is much more sedentary than his primitive ancestors) to recent studies that show a plateau effect when it comes to our ability to burn calories.
“The more physically active you are, the more your energy expenditure is going to increase,” Bergouignan says. “Your body weight is a result of how many calories you eat versus how many calories you burn. The idea is that there is threshold, a ceiling value of burning calories that you can’t go higher than. This is likely true, but the threshold is very high, on the level of what professional athletes burn. There is a ceiling, but it’s less applicable to the general population. For the general population, the rule of the more they move, the more calories they will burn is much more plausible.”
The paper also includes the results of prospective studies that followed participants over a period of years to show that those who were the most active at baseline gained the least amount of body weight over time; randomized clinical trials that examined the effects of increasing or decreasing physical activity; and studies on the relationship between energy intake and energy expenditure.
Keep it light
Not surprisingly, given her research interests, Bergouignan focuses much of the paper on what she calls “the overlooked contribution of light physical activity” in combating our increasing sedentariness, which has become a serious health problem.
“Epidemiological studies have found that physical inactivity is responsible for or a contributing factor to some 35 different diseases, including cardiovascular and coronary disease, type 2 diabetes, obesity, and certain type of cancers, as well as depression and poor mental health,” she says. “And doing exercise doesn’t necessarily mean you can offset the adverse health effects of sedentary behaviors. If you spend nine to 12 hours sitting in front of a computer at work and the TV at home, 30 minutes of exercise a day will not offset the effects of sedentary behaviors.”
Since the compensatory response to exercise can also include increased sedentariness (“I worked out this morning, so it’s OK to sit in front of the TV the rest of the day”), it’s important not to overlook the importance of lighter physical activity on overall weight management, Bergouignan says. It’s advice you’ve likely heard before: Park farther away. Take the stairs instead of the elevator. Get up and walk around once every hour. It’s especially helpful for people with obesity or who are overweight, who, according to the research, exhibit more compensatory behaviors after exercise such as excess eating or sedentariness.
“The question is, are they overweight because they have compensation? Or do they have compensation because they are overweight?” says Bergouignan, who is currently conducting a study to see if breaking up sedentary behaviors with physical activity can help prevent people with prediabetes from developing type 2 diabetes. “If you start just by becoming more active, you can retrain your body to become more efficient. If you train your body to respond to exercise, then you will likely have less and less compensation in response to exercise.”
Thinking beyond exercise
Simply put, Bergouignan says, all levels of physical activity need to be considered when it comes to fighting the obesity epidemic and associated chronic disease. From a public health perspective, promoting light physical activity and reducing sedentariness could go a long way toward lowering obesity rates, though further studies are needed to develop practical strategies for doing so.
“When we think about management of obesity and the role of physical activity, we only think about exercise, when in fact, physical activity is multicomponent,” she says. “The idea is that by tapping into this light physical activity that is never really considered, we could move things forward, especially for people who are very sedentary.”
