Last October a coalition of many of the corporate contributors to our obesogenic environment(Reference Poston and Foreyt1), including some of the world’s largest food manufacturers and retailers, launched the Healthy Weight Commitment Foundation, whose aim, they say, is to try to reduce obesity, especially childhood obesity, by the year 2015.
Their plan to do so is to promote application of the ‘energy balance’ concept. The Foundation aims to promote the energy-out aspect of this equation. Their fact sheet says ‘lack of physical activity continues to attribute to the obesity problem’ and goes on to say that ‘more than half of adults do not engage in physical activity at levels consistent with USDA physical activity guidelines of 60 minutes per day’(2). The fact sheet does not mention the other part of the energy balance equation, energy-in, which is perhaps unsurprising, for these corporations are in the energy-in business.
In the same month the American Academy of Family Physicians announced that it would accept a grant from the Coca Cola company to ‘develop consumer education content on beverages and sweeteners for FamilyDoctor.org’, which is their consumer health website. The Wall Street Journal published a supportive editorial, quoting Coca Cola CEO Muhtar Kent as saying: ‘It's not just about calories in. It's also about calories out’(Reference Kent3).
It is widely believed that declining levels of physical activity are a major cause of the current obesity epidemic, but new evidence challenges this notion(Reference Westerterp and Speakman4, Reference Swinburn, Sacks and Ravussin5). Besides, it has been estimated that 60–90 min daily is necessary to prevent weight regain in previously obese individuals and 45–60 min daily to prevent the transition from overweight to obesity(Reference Saris, Blair and van Baak6). Such levels of daily physical activity are, for most people now, surely unrealistic and unachievable.
An indigestible truth
What is much more striking than any general decline in physical activity – energy-out – is the recent dramatic increase in consumption of food – energy-in. Single meals prepared outside the home can now contain anywhere between half to a full day’s worth of calories(Reference Wootan, Osborn and Malloy7). Portion sizes of processed foods and drinks have greatly increased, and value-added items can dramatically increase the calorie content of meals(Reference Chandon and Wansink8, Reference Young and Nestle9). Caloric underestimation of restaurant meals is common, especially among the already overweight or obese(Reference Wansink and Chandon10). Calories in meals prepared at home have increased as well. One recent study estimated that since 1936, calories per serving of classic recipes have grown by 63 %(Reference Wansink and Payne11). It seems most unlikely that such caloric excesses can be balanced by increased physical activity.
The notion promoted by industry – that maintaining and achieving healthy weights is mostly or all about increased physical activity – is not well based on evidence. Without dramatically unrealistic amounts of increased activity, the calories burned through exercise are insufficient to ‘balance’ calories consumed. To date no one has managed to create a public health strategy that has markedly increased physical activity. Consequently a focus on energy-out for energy balance is an inadequate and a potentially dangerous approach, because it is liable to encourage people to ignore or underestimate the greater impact of energy-in.
The message put forth can no longer be that of the Foundation – of which Coca-Cola is a member – which proposes that obesity management and prevention can be accomplished simply by offering ‘healthy’ or ‘nutritious’ alternatives, so long as they are accompanied by enough physical activity for ‘balance’, while avoiding any explicit guidance on energy-in.
Physical activity has many important health benefits but it cannot be used as the lynch-pin for obesity management and prevention. As public health professionals we all must concentrate our efforts around effective nutrition policy, and the promotion and provision of lower-calorie, nourishing and delicious foods. We must also give explicit guidance on how to consider energy intake within the context of overconsumption of calories. While such initiatives may be hard for the food industry to swallow, we commend them to all our public health agencies.
