High levels of physical activity do not counteract poor diets

Demonstrating that you cannot “outrun” poor diets, researchers found that exercise only benefits health when complemented with healthy eating

People who have both high levels of physical activity and a high-quality diet had the lowest risk of death, showing that poor diets cannot be fixed with high levels of exercise.

“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.”   

High quality diets were considered to include at least five portions of fruit and vegetables every day, as well as two portions of fish per week and lower consumption of red meat – particularly processed meat, according to researchers.

Researchers from the University of Sydney examined the independent and joint effects of diet and physical activity on all-cause, cardiovascular disease and cancer mortality using a large population-based sample (360,600) of British adults from the UK Biobank.

Mortality risk was reduced by 17% with good diets and high amounts of exercise

For those who had high levels of physical activity and a high-quality diet, their mortality risk was reduced by 17% from all causes, 19% from cardiovascular disease and 27% from selected cancers, as compared with those with the worst diet who were physically inactive.

Lead author Associate Professor Melody Ding at the University of Sydney said: “Both regular physical activity and a healthy diet play an important role in promoting health and longevity.

“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.”

Co-author Joe Van Buskirk, from the School of Public Health, Faculty of Medicine and Health, added: “Adhering to both a quality diet and sufficient physical activity is important for optimally reducing the risk of death from all causes, cardiovascular disease and cancers.”

Exercise could lessen detrimental physiological responses to over-eating

Associate Professor Ding said: “This study reinforces the importance of both physical activity and diet quality for achieving the greatest reduction in mortality risk.

“Public health messages and clinical advice should focus on promoting both physical activity and dietary guidelines to promote healthy longevity.”

A few other studies have tried to identify other important health benefits maintaining a healthy diet and exercise can bring, where they found that high-intensity exercise may actually counteract detrimental physiological responses to over-eating – however, the long-term effects on how diet and physical activity interact with each other remained less explored.

The findings from this study confirm the importance of both physical activity and quality diet in all-cause and cause-specific mortality.