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You Can’t Outrun a Bad Diet, Study Shows

Have you ever indulged in a decadent treat after a workout, claiming you’ve “earned it” after burning extra calories? Or justified a junk-food binge by promising to exercise extra hard the next day to work it off? Well, a new study suggests exercise can’t make up for poor dietary habits in the long run. The research shows the converse is also true: you can’t try and balance out an inactive lifestyle with a healthy diet. While an occasional indulgence or skipped workout won’t do much harm, the new research shows that both physical activity and a healthy diet are needed to live a longer, healthier life.

The study looked at over 350,000 adults age 40 to 69 to examine the links between physical activity and diet with death from all causes, including cardiovascular disease and cancer. While there’s plenty of research about each of these factors independently, the study authors aimed to close a knowledge gap: how do nutrition and exercise work together to impact longevity? And is one factor more important than the other?

In this study, participants self-reported how many minutes of exercise they performed a week and at what intensity. For reference, the general exercise guideline for most people is 150 minutes of moderate (think brisk walking) or 75 minutes of vigorous (running) physical activity a week. Diet was measured on a less comprehensive scale. The researchers rated participants’ diets either poor, medium or good based on how many servings of fruits and vegetables, fish, red meat and processed meat were consumed. A ‘good’ diet included at least five daily servings of fruits and vegetables, two servings of fish, no more than two servings of processed meat and no more than five servings of red meat per week.

When reviewed separately, both high levels of physical activity and a high-quality diet positively impacted health outcomes and longevity. The researchers found that the participants with the healthiest diets had a 14 percent lower risk of cancer mortality than those with poor or medium diets, for example. And independent of diet, increased physical activity levels provided protection of death from any cause. However, these effects were found to be most powerful when both healthy diet and adequate physical activity were combined. In fact, those who performed high on both measures had a 17 percent lower risk of death, a 19 percent lower risk of death specifically from cardiovascular disease and a 27 percent lower risk of death from certain cancers (when compared to participants with poor diets and sedentary lifestyles).

This shows us that paying equal attention to exercising and eating well is the best way to avoid chronic disease and early mortality and that you can’t make up for a lack of one by paying extra attention to the other.

“Sensationalized headlines and misleading advertisements for exercise regimens to lure consumers into the idea of working out to eat whatever they want have fueled the circulation of the myth about exercise outrunning a bad diet,” said the researchers. “Our study provided important evidence for health professionals that exercise doesn’t fully compensate for a poor diet and that we should recommend and advocate for both.”

Health: More Than Weight Loss

The ‘exercise outrunning a bad diet’ myth not only detracts from the importance of healthy eating, but also positions burning calories and weight as the most important indicators of health and well-being. The idea behind the myth is that if you can burn off the same amount of calories consumed in a binge or indulgence, you can offset the consequences. In reality, measuring health is more complex and this mindset only shows one side of the picture. While energy consumption and expenditure are important to weight loss, when looking at long-term health impacts (mortality and disease), nutrition and exercise go hand in hand.

“People constantly obsess about calories, but it’s not really as simple as that,” said the study’s lead author, Melody Ding. “I think people should move away from this ‘burn this many calories so I can eat this much’ [approach] and more towards overall diet quality and doing activity for general health, not just for reducing a calorie surplus.”

Making an effort to improve diet and increase physical activity provides benefits beyond weight control. It can improve all aspects of health, including increased energy levels, reduced inflammation, better sleep, improved immune function, reduced risk of chronic disease and lowered risk of early mortality. In general, people should aim for at least 150 minutes of moderate to vigorous exercise a week, should eat around five servings of fruits and vegetables daily and limit red and processed meat consumption to a couple of times a week. Achieving these goals doesn’t have to be difficult or overwhelming. Instead of focusing on restrictions and what you can’t eat or do, try thinking about what you can add to your lifestyle to achieve your health goals. That could be incorporating more fresh fruit and vegetables into your recipes or going for a 15-minute walk every day, for example. In the long run, your body will thank you for it.

[Hannah Sabitoni]

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