Joe Matthews, MSc, BSc (Hons), SENr and Craig Sale, PhD, FACSM |
New UK research suggests that physical activity calorie equivalent (PACE) food labeling can reduce the number of kilocalories (Calories) consumed, encourage healthier food choices and combat the rising obesity epidemic. The labeling provides the product’s Calories as a walking or running equivalent; depicted by the number of minutes of activity required to burn the Calories.
One concern is the widespread acceptance of the study conclusions that have propagated across the UK media. When looking at the headlines of the study, there is reportedly a clear benefit of PACE labeling compared to no labeling, but upon closer inspection of the study data, any potential benefit to PACE labeling when compared to Calorie-only labeling (i.e., what we already have) is far less clear. For a number of reasons, we question whether this is the best approach to reduce obesity and improve public health as suggested in the media outputs relating to this study.
To burn off the Calories you will need to walk or run for [?] minutes.
While calorie intake can be approximated in a single value, accurate estimation of calorie expenditure during activity differs based upon a number of factors including: sex, body size, fitness level, limb length and proportion of muscle mass—as well as the speed of walking or running itself.
For example, take two individuals: a 40 kg child and a 90 kg adult. They both choose the same snack that contains 150 kcal. Assuming a moderate walking speed of three miles per hour, the child would need to walk for approximately 65 minutes and the adult for approximately 29 minutes to burn off the Calories ingested—this is without taking into account other factors that influence energy expenditure.
It is difficult to see how we can reconcile such divergent physical activity calorie equivalents into a single unified value for consumers. In its current state, many individuals will substantially over or under compensate their activity if following the PACE labeling guidance. This does little to improve the public’s understanding of effective weight-management behaviors.
Could PACE labeling lead to unhealthy eating or exercise behaviors?
PACE labeling conveys the idea that all ingested Calories need to be counteracted by an equal dose of physical activity. This ignores the energy expenditure from resting metabolism, diet-induced thermogenesis and non-exercise activity thermogenesis. Individuals may feel guilty and adopt unhealthy or excessive exercise behaviors to counteract their calorie-intake, even when that intake may be within their habitual energy balance.
Beat, the UK’s leading eating disorder charity, released a statement expressing concern that PACE labeling “…risks exacerbating illness among those suffering from or vulnerable to eating disorders.” Further, the National Institute for Health and Care Excellence (NICE) list the use of compensatory weight-management behaviors including “excessive exercise” as a common sign of an eating disorder. It is possible that PACE labeling will contribute to negative relationships with food and exercise.
While it would undoubtedly a good idea to increase the physical activity levels of the UK population, focusing on walking and running to expend ingested Calories is an over-simplistic approach to a complex problem. The emphasis on activity to burn Calories ignores the multitude of health benefits that can occur independent of changes in bodyweight.
In contrast to the messages presented in the UK media, PACE labeling does not appear to confer a benefit over conventional calorie labeling. In addition, it has the potential to negatively affect those with or who are vulnerable to eating disorders. The few studies investigating PACE labeling do so in controlled conditions (i.e., a laboratory or restaurant setting) and there is a lack of research in free-living individuals. There is also an absence of follow-up data to see if individuals change their physical activity habits over time. For now, it seems that current UK Calorie-labeling carries the same benefits, but with fewer negatives than PACE labeling.
Joe Matthews, MSc, BSc (Hons), SENr, is a Sport and Exercise Nutritionist, Lecturer at Birmingham City University, and PhD Researcher in Physiology at Nottingham Trent University, UK. His research is broad and includes dietary intake and weight-management in combat sport athletes; and the physiological roles of carnosine and beta-alanine in humans.
Craig Sale, PhD, FACSM, is a Professor of Human Physiology working in the Musculoskeletal Physiology Research Group at Nottingham Trent University. He is Director of the Sport, Health and Performance Enhancement Research Centre. Craig is a Fellow of the American College of Sports Medicine (ACSM), Chair of the ACSM BONE Interest Group, a section Editor for the European Journal of Sports Sciences and Editor in Chief of Nutrition and Health.