| Feb 24, 2015
By Amy Bidwell, Ph.D.
A diet high in added sugar has already been established to be correlated with increased weight and metabolic disturbances. However, what happens when a person is ingesting moderate amounts of added sugar, either in the form of sucrose or high fructose corn syrup (HFCS) while also being physically inactive? Moreover, in this context, what constitutes being physically active?
Although previous research has shown that a diet high in fructose can cause deleterious metabolic effects to the body, these studies tend to use an excessive amount of added sugar, which often results in weight gain. Moreover, high fructose corn syrup is now being replaced with sucrose (table sugar) in many foods, giving the indication that they are “natural” and hence, healthier; although from a metabolic standpoint, HFCS and sucrose are essentially the same. This change in labeling has resulted in an even larger influx of added sugar in our diet.
We have recently published a series of papers investigating the effects of a diet high in a more moderate amount of added fructose (~17 percent calories from added fructose). We found through this work that, in as little as two weeks, a healthy young adult’s metabolic profile begins to be negatively altered. The observed consequences included increased postprandial triglyceride, very-low density lipoproteins levels and low grade inflammation when subjects were physically inactive. These results were found without subsequent changes in weight.
So now the question is this: What if a person who is ingesting only a moderate amount of added fructose, while maintaining their weight, is also physically inactive? According to the most recent ACSM Position Statement on exercise for apparently healthy adults, 30-60 minutes of moderate-intensity exercise is recommended, five days per week. The problem is that a person can go to the gym for 30-45 minutes, five days per week and still only be getting ~4000-5000 steps per day because they may be sitting at a desk at work or school all day then on the couch at night. This creates the active couch potato conundrum. The person thinks they are being active because they do their structured recommended exercise for 45 minutes per day. But, the fact is that they are inactive the remaining 23 hours per day! If you compound that circumstance with having just one bowl of sugary cereal for breakfast and a “natural” sweetened ice tea for lunch or dinner, you now have a person whose metabolic profile is being unfavorably altered, even though they were trying to be healthy.
Even if someone is diligently going to the gym daily and maintaining a proper weight, they are still doing their body harm if they are not being active throughout the day and eating a diet composed of low sugar, unprocessed, whole foods. We have done such an immense job at promoting regular, daily exercise, we need to now take it one step further and begin to educate people on the harms of being physically inactive the remaining 23 hours per day. Additionally, there needs to be more focus on educating people on the metabolic disadvantages of a diet including even a moderate amount of added sugar, regardless of whether it is from sucrose or high fructose corn syrup. Viewpoints presented on the ACSM blog reflect opinions of the authors and do not necessarily reflect positions or policies of ACSM.
Dr. Amy Bidwell is an assistant professor in the Department of Health Promotion and Wellness at the State University of New York at Oswego where she teaches exercise physiology and nutrition. Her research focuses on the adverse effects of physical inactivity and its interaction with diet, obesity and obesity-related diseases. Specifically, Dr. Bidwell researches the adverse effects of a diet high in fructose and low in physical activity. She is a member of ACSM.
This commentary presents Dr. Bidwell’s views on the topic related to her research specialization. See the November 2014 issue of Medicine & Science in Sport & Exercise® (MSSE) for a report that she and her colleagues authored on findings from one of their recent investigations in this topic area.