There has been a lot of conversation and extensive 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, analysing UK Biobank data, may provide the answer.

Researchers found that people who engaged in high levels of physical activity and 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 have a lower mortality risk 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 a 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 specialises 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 -

Analysing Exercise And Diet Habits

The researchers analysed existing health records for 346, 627 U.K. residents who enrolled in the UK Biobank between April 2007 and 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 as 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 PDAR cancers by 27%.

The higher the level of MVPA, the greater the reduction in all-cause and PDAR cancer mortality risk, with the most active group attaining a 13% to 14% reduction over the least active group.

The same was true for VPA, although it also had a beneficial effect on cardiovascular disease mortality risk. However, the two middle levels curiously reduced individuals’ risk more than the highest level of activity.

As for the reason behind vigorous activities’ larger effect on cardiovascular disease mortality risk, the authors note:

“It has been argued that VPA may lead to more physiological adaptations and elicit more insulin-sensitising and anti-inflammatory effects than lower-intensity physical activity, which may explain why the stronger association with VPA is particularly pronounced for CVD mortality in our study.”

The highest-quality diet alone — without MVPA or VPA — had no statistically significant bearing on all-cause or cardiovascular mortality risk. It did, however, reduce their chances of PDAR cancer mortality by 14%.

In terms of the interaction between physical activity and diet, Dr Ding said, “Diet plays a similar role in mortality risk in those who are physically active and those who are inactive, and vice versa.”

Living longer

As far as optimising one’s chance of a long life based on the study’s insights, Dr Ding said:

“I guess the simplest answer is to adhere to public health guidelines, such as The Eatwell Guide for eating, and the WHO guidelines on physical activity and sedentary behaviour. These guidelines are based on solid evidence.”

Taking physical activity and diet separately, Routhenstein noted:

“I need to assess where the person is in their exercise journey, their medical conditions, and their limitations to guide them appropriately. Too much too fast or too heavy an intensity, both in aerobic or anaerobic exercise, can lead to negative side effects.”

“When it comes to exercise, we are looking ideally for 150 to 225 minutes of weekly moderate-intensity cardiovascular activity, about 60 minutes of low to medium intensity resistance exercise, and regular stretching. [Start] your day with a balanced breakfast and [have] therapeutic foods, such as lean protein, vegetables and fruits, whole grains, nuts, seeds, and legumes, in line with your hunger/satiety cues.”

- Michelle Routhenstein, nutritionist -

“For your diet to be truly heart-healthy, it needs to be long-lasting,” added Routhenstein. “Quick fixes do not work, and starting a diet plan that won’t last long term isn’t effective.”