Do Exercise Stats Belong on Nutrition Labels?

As rates of obesity continue to climb worldwide, public health officials are constantly seeking new and innovative ways to encourage health diets and behaviors. In the 1990s, the US Congress passed the Nutrition Labeling and Education Act, mandating that information like calories and ingredients be included on all food labels. Over the last few years, an increasing number of restaurants have been voluntarily adding calorie counts to their menu items, and starting in December 2016, the FDA will require this labeling in all chain restaurants and similar retail food establishments.

What would happen if we shift perceptions from the number of calories consumed to how to burn them off?

But in January of this year, the UK's Royal Society of Public Health proposed a new labeling system pairing calorie counts on purchased foods with the amount of exercise required to burn the calories. The idea is gaining traction: A recent piece published in the British Medical Journal emphasized the potential benefits and called for further research with an eye towards implementing the labels throughout the UK. (Although there are no current plans to include physical activity equivalents on American labels, an effective pilot program in the UK may affect future proposed changes.)

The current by-the-numbers breakdown of calories on US nutrition labels has done little to curb American consumption: Labeling restaurant items with calorie counts was expected to influence purchasing habits, but has failed to cause any substantial changes. So what would happen if we shift perceptions from the number of calories consumed to how much work it would be to burn it off?

What is the proposed label?

Current labels both in the US and Britain detail critical information about purchased food. The FDA's March 2014 proposed update to the nutrition facts label includes modifications on the required nutrients, updated serving size requirements, and unveiled a new design that emphasizes calorie count and the number of servings in each container. The familiar black and white box filled with numbers and the inscrutable "daily values" remains the same, just slightly rearranged.

But calorie counts are an abstract number and easily skimmed over:€ The label tells you that the can of Coke you're popping open has 140 calories, but what does that really mean? Understanding those labels requires both health literacy and an interest in what it says, and many people barely glance at the complicated nutrition facts label before purchasing (a decision process, according to one study, that consumers make in less than one-third of a second).

The goal is to make consumers stop and think: "Is that 264-calorie Milky Way really worth a half-hour jog?"

The new labels offer a way to reframe how consumers think about the number of calories they consume. "Providing calories in the context of walking or running is something that anyone, regardless of education or nutritional literacy, can understand in a short space of time," says Shirley Cramer CBE, chief executive of RSPH and author of the BMJ article.

The goal, according to Cramer, is to make consumers stop and think: "Is that 264-calorie Milky Way really worth a half-hour jog?" Does knowing that those 400-calorie medium-sized fries translates to a 100-minute bike ride make you go with a side salad instead? If diners decide to go with the extra calories, the label offers a guide for how much exercise is needed to help maintain a healthy weight.

Essentially, proponents believe that an image informing you that the can of Coke corresponds to 23 minutes of aerobic exercise will be a better modifier of behavior than the calorie count of 140, which is buried along with a dozen other numbers on food packaging. "It's difficult for people to know what one calorie equates to," Cramer says. "By providing calorie information in terms of physical activity, it makes it more relatable to people's lives and things they do on a daily or weekly basis."

Polling by the RSPH suggests that activity labeling would make shoppers three times more likely to choose healthier product, eat less of the product, or engage in the degree of physical activity listed on the label. No one claims that these labels will be a panacea to the obesity epidemic, but rather that it can play a role in a series of new initiatives to combat unhealthy lifestyles. These labels are not a new concept, showing up in research literature going back several years. But the endorsement of RSPH moves things forward and, pending further research, may lead to an official change to the labels themselves.

Are there flaws in the system?

There have long been questions about the calorie counting system itself: Our bodies don't actually absorb every calorie from the food we consume, and metabolisms can differ widely between individuals. Variations in everything from height and age to hormone levels can impact both how we absorb calories and how we expend them. With nearly two-thirds of UK citizens registering as overweight or obese, will that inform which exercise estimates are placed on the label? Or will they rely on the common fallback of a male with a normal BMI to calculate exercise times?

Although the BMJ article calls for further research, it also cites some dubious studies in arguing that exercise labels will be more effective than calorie counts alone. For example, a widely reported 2011 study published in the American Journal of Public Health purported to find that labels stressing physical activity equivalents were more effective at influencing the purchase behaviors of adolescents than those with calorie counts alone. However, a response article entitled "How Statistics Can Mislead" questioned these findings, demonstrating that with appropriate analysis, there was actually no substantial difference noted between the effects of labels with calorie counts as compared to those with physical activity listings.

Another study, published last year in the journal Pediatrics, also suggested that physical activity labels may be effective at changing parents' decisions on what food they order for their children in fast food restaurants. A 2015 study in the Journal of Prevention and Intervention in the Community added further support to the argument that these labels will influence food selections, this time focusing on the adolescents themselves. But in both of these cases, the data was based on hypothetical purchases, not real-world examples. It is entirely possible that, as was the case with putting calorie counts on restaurant menus, the labeling works in theory but not in practice.

None of which is to say that the labeling will be more or less effective than calorie counts — just that it may make no difference at all. But could it actually do harm?

Some have argued that detailing such a system of checks and balances may encourage eating disorders. Dr. Catherine Carpenter, an associate professor at UCLA Fielding School of Public Health, emphasizes that these labels will influence all people differently, but sees the potential to encourage disordered eating habits in some individuals. For example, "Anorexics and bulimics may see the labels literally€ — e.g. what will it take to get rid of these calories," she says, "and binge eaters may not care — €”e.g. they will continue to binge, and, in fact, may choose the higher calorie foods. For unhealthy eaters, or those with eating disorders, or sedentary individuals, physical activity equivalents may make matters worse."

A focus on calorie and physical activity equivalents also misses the critical fact that health is not only about maintaining a normal BMI. A grilled chicken salad may have the same number of calories as a candy bar, but one is far better for you —€” not all calories are created equal. "Just listing exercise equivalents will only link food to calories burned and will not provide information about attributes of food that influence health — including types of fats (trans fat), refined carbohydrates (sugar and fructose), and sodium content, among other things," Carpenter says. The new labels do not propose to eliminate that information from food packaging, but they will shift the focus to exercise, potentially making people even less likely to read the further breakdown of the nutrients in their food.

Is there any point to changing the labels?

Increasing physical activity has been repeatedly shown to have significant health benefits in individuals across a range of BMIs. Research also demonstrates a correlation between level of physical activity and obesity. An initiative that succeeds in increasing physical activity for citizens without causing harm will almost certainly have a positive impact on the health of the population as a whole.

Critically, these labels address the fact that health literacy in both the US and internationally is extremely poor. Nutrition labels offer a wealth of information but no explanation —€” it takes time, education, and inclination to understand their meaning and significance. Pictograms, on the other hand, are part of a universal language. It takes only seconds to process an image of a person on a bicycle or someone going for a run.

Do we have evidence that these labels will work? Absolutely not. Would obesity prevention efforts be better served by increasing access to healthy foods, providing safe areas to exercise, and informing people about healthy behaviors? Undoubtedly. But visual aids may encourage people to embrace a healthy lifestyle while helping to overcome some the education and language barriers that impede healthy decision making in food purchasing. So if evidence bears out that the labels are not harmful, it's probably worth a shot.

Caroline Weinberg is a science and health writer based in New York City.
Editor: Erin DeJesus