You can’t exercise away poor dietary choices, study finds

There has been a lot of conversation — and a great deal of research — attempting to determine whether exercise or a healthy diet is more important for longevity. A new study led by researchers from the University of Sydney in Australia analyzing UK Biobank data may provide the answer.

Researchers found that people who engaged in high levels of physical activity and also ate a high quality diet had lower mortality risks.

For anyone who believed that one can exercise away poor dietary choices, this study suggests otherwise.

People who engage in one or the other lowered the risk of mortality to a lesser degree. Study corresponding author, associate professor Dr. Melody Ding, told Medical News Today:

“These groups still do better (and statistically significant) than the group with poor diet and lowest physical activity, but the group with the best diet and moderate or high physical activity levels do the best!”

The study focused on deaths due to all-cause mortality, cardiovascular disease (CVD), and adiposity-related (PDAR) cancers.

Cardiology dietician Michelle Routhenstein, who specializes in heart health, and was not involved in the study, told MNT:

“The study results are no surprise to me. Many people have come to see me in my private practice after suffering a heart attack when training for their fourth or fifth marathon, or right after doing a CrossFit exercise.”

“When I do a comprehensive evaluation of their lifestyle, it is apparent that they thought their intense daily exercise regimen would make up for their poor, unbalanced diet, and it simply doesn’t.”
— Michelle Routhenstein, cardiology dietician

The study is published in BMJ Sports Medicine.

Analyzing exercise and diet habits

The researchers analyzed existing health records for 346, 627 U.K. residents that enrolled in the UK Biobank between April 2007 to December 2010. The health of these individuals was followed for an average of 11.2 years. For this study, the UK Biobank data were linked to the National Health Service death records until 30 April 2020.

For the purposes of their analysis, researchers considered the number of minutes people engaged in walking, moderate-to-vigorous physical activity (MVPA), and vigorous-intensity physical activity (VPA). For both MVPA and VPA, they used a 1-4 ranking system.

A high quality diet consisted of 4.5 cups or more of vegetables or fruit per day, two or more servings of fish weekly, and less than two servings of processed meat or less than five servings of red meat weekly.

The selection of target foods reflects recommendations from the American Heart Association, with the authors noting:

“These food groups were selected as markers for overall diet quality because other important dietary components and/or nutrient groups, such as whole grains and dairy, were not measured during baseline assessment.”

The researchers rated the individuals’ diet quality poor, medium, or one of two levels of best.

The best results

Compared to physically inactive individuals who ate the lowest-quality diet, those engaging in the highest activity levels and eating the highest-quality diet reduced their risk of all-cause mortality by 17%. They also reduced their mortality risk of cardiovascular disease by 19% and of PDAR cancers by 27%.