A poor diet can't be entirely offset by more exercise, study finds
Planning an extra half hour in the gym to counteract the effects of that extra doughnut in the morning? Think again. According to new research from the University of Sydney, high levels of exercise cannot offset the damaging effects of poor dietary choices.
Lead author on the new study Melody Ding, set out to fill a gap in the research after finding a distinct lack of studies looking at the long-term influence of diet and exercise on longevity and health. Lots of longitudinal research looked at one or the other, and there was short-term research suggesting high-intensity physical activity may counteract some of the detrimental effects of overeating. But Ding wanted to know if exercise could offset the health risks of a bad diet in the long term.
Tracking health data from more than a quarter of a million subjects the new study found those who vigorously exercise while still eating poorly were certainly still better off than those who don’t exercise at all, but the benefits of physical activity definitely diminished when accompanied by an unhealthy diet.
“Some people may think they could offset the impacts of a poor diet with high levels of exercise or offset the impacts of low physical activity with a high-quality diet, but the data shows that unfortunately this is not the case,” Ding said. “Both regular physical activity and a healthy diet play an important role in promoting health and longevity.”
The study looked at all-cause mortality, as well as more specific metrics of cardiovascular and cancer mortality. Across all metrics those people who exercised consistently and ate a high quality diet showed lower risk of mortality compared to those who were physically inactive with a poor diet.
The study was not without its limitations, as the health data analyzed lacked detailed insights into specific dietary characteristics. A high-quality diet was broadly defined here as at least five portions of fruit or vegetables each day, minimal consumption of red meat and two portions of fish per week.
So without a more granular tracking of things we know are bad for health, such as fast food or sugary soda, it is hard to evaluate exactly what the impact of exercise in conjunction with a very poor diet may be over the long term. Speaking to the Sydney Morning Herald, Ding accepted there were limitations in the data available to the researchers. In the future she hopes more research can unpack these more specific associations.
Ding does stress these findings do not mean someone eating poorly should abandon any form of exercise. There are still obvious benefits to physical activity in the absence of good dietary choices, but the study does indicate exercise doesn’t completely counteract the negative impact of unhealthy food.
“Independent of each other, both diet and physical activity are critical to health and longevity,” Ding said. “One should not feel that if they cannot have a healthy diet they should give up on physical activity as well and vice versa. However, if possible, try to do both things right.”
The new study was published in the British Journal of Sports Medicine.
Source: University of Sydney