You can’t exercise to avoid poor dietary choices, study says

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Exercising alone without healthy eating habits may not be enough to reduce mortality risk. Lumina/Stocksy
  • A new study finds that exercising to compensate for poor diet doesn’t really work in terms of reducing mortality risks.
  • Similarly, eating well but staying inactive may help reduce the risk of dying from certain types of cancer to some extent, but does nothing for cardiovascular or all-cause disease mortalitythe researchers found.
  • The researchers also found that those who exercised the most and ate the healthiest foods significantly reduced their risk of dying from all causes, cardiovascular disease, or certain types of cancer.

There has been a lot of talk, and a lot of research, trying to determine whether exercise or a healthy diet is more important for longevity. A new study led by researchers at the University of Sydney in Australia looking at data from the UK Biobank may provide the answer.

The 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 could exercise to eliminate poor dietary choices, this study suggests otherwise.

People who engage in one or the other reduced mortality risk to a lesser degree. The study’s corresponding author, Associate Professor Dr. Melody Ding, said Today’s medical news:

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

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

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

“The results of the study do not surprise me. Many people have come to see me in my private practice after suffering a heart attack while training for their fourth or fifth marathon, or right after doing a CrossFit workout.”

“When I do a thorough lifestyle assessment, it’s clear they thought their intense daily exercise regimen would make up for their poor and unbalanced diet, and it just isn’t.”
— Michelle Routhenstein, cardiology dietitian

The study is published in BMJ sports medicine.

The researchers analyzed the existing health records of 346,627 UK residents who were enrolled in the UK Biobank between April 2007 and December 2010. These people’s health was followed for an average of 11.2 years. For this study, data from the UK Biobank was linked to NHS death records up to 30 April 2020.

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

A high-quality diet consisted of 4.5 cups or more of vegetables or fruits per day, two or more servings of fish per week, and fewer than two servings of processed meat or fewer than five servings of red meat per week.

The target food selection reflects the recommendations of the American Heart Association, and the authors note:

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

The researchers rated the individuals’ diet quality as poor, average, or one of two better levels.

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

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

The same occurred with VPA, although it also had a beneficial effect on the risk of mortality from cardiovascular disease. Interestingly, however, the two middle levels reduced individuals’ risk more than the highest level of activity.

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

“It has been argued that VPA may lead to more physiological adaptations and elicit more anti-inflammatory and insulin-sensitizing 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 association with risk of all-cause mortality or risk of cardiovascular mortality. However, it reduced your chances of PDAR cancer mortality by 14%.

As for 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.”

As for optimizing the 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, like The Eatwell Guide to eating, and the WHO guidelines on physical activity and sedentary behavior. 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 in order to properly guide them. Too much, too fast, or too intense in both aerobic and anaerobic exercise can lead to negative side effects.”

“When it comes to exercise, we ideally look for 150 to 225 minutes of moderate-intensity cardio weekly, 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,” Routhenstein added. “Quick fixes don’t work and starting a diet plan that doesn’t last long isn’t effective.”

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