The relative role of diet and physical activity in obesity To the Editor: Cuenca-Garc
ıa et al concluded that physically active and leaner adolescents have higher energy intake than less active adolescents with higher adiposity.1 From a scientific point of view, we are not able to precisely measure individual components of energy intake and energy expenditure. Many errors in the assessment of energy balance currently exist. There is evidence that the energy intake estimation by 24-hour recalls produces a differential misclassification in obese adolescents.2 New technologies in development may be more accurate. Although the authors mention this limitation, their conclusion does not consider this information bias. Regarding energy expenditure, covariates such as moderate or vigorous physical activity were studied. However, the 2 physical activity levels used should not be interpreted as good markers of energy expenditure. In fact, in validation studies with doubly labeled water, ActiGraph accelerometers (GT1M, Pensacola, Florida) showed a lower correlation (r = 0.30) compared with other models (Tracmor) (r = 0.87).3 Furthermore, obese subjects tend to have similar activity energy expenditure (by doubly labeled water) compared with lean people.4 Thus, more accurate data from longitudinal studies are still needed to understand how human energy balance is regulated. Public health recommendations to prevent obesity that redirect the responsibility toward just 1 behavior (physical activity) are too simplistic and potentially dangerous. Indeed, this is what some food and drink companies are currently doing, employing corporate social responsibility campaigns to promote healthy lifestyles and focus on physical activity without recognizing the role of diet in the obesity epidemic.5 The author is supported by the S~ao Paulo State Research Foundation (2012/05723-8).

Juan Pablo Rey-L
opez, PhD Department of Preventive Medicine School of Medicine University of Sao Paulo Sao Paulo, Brazil http://dx.doi.org/10.1016/j.jpeds.2013.12.016

References 1. Cuenca-Garc
ıa M, Ortega FB, Ruiz JR, Labayen I, Moreno LA, Patterson E, et al. More physically active and leaner adolescents have higher energy intake. J Pediatr 2013 Oct 3 [Epub ahead of print]. 2. Bandini LG, Schoeller DA, Cyr HN, Dietz WH. Validity of reported energy intake in obese and nonobese adolescents. Am J Clin Nutr 1990;52: 421-5. 3. Plasqui G, Bonomi AG, Westerterp KR. Daily physical activity assessment with accelerometers: new insights and validation studies. Obes Rev 2013; 14:451-62.

4. Westerterp KR. Physical activity, food intake, and body weight regulation: insights from doubly labeled water studies. Nutr Rev 2010;68:148-54. 5. Dorfman L, Cheyne A, Friedman LC, Wadud A, Gottlieb M. Soda and tobacco industry corporate social responsibility campaigns: how do they compare? PLoS Med 2012;9:e1001241.

Reply To the Editor: We thank Dr Rey-L
opez for re-emphasizing the need to avoid simplistic public health messages in the fight against youth obesity. Indeed, our point was that adiposity in youth is not a simple problem of just high/low energy intake (EI) or expenditure (EE).1 Food products with a negative impact should be identified and their consumption restricted.2 We agree that nutritional surveillance research is currently failing to provide accurate estimates of the habitual EI, yet efforts are being made, and the Healthy Lifestyle in Europe by Nutrition in Adolescence study is a good example. Our findings did not support the common belief that youth with higher adiposity levels are those with higher EI, but rather the opposite. Moreover, this finding was confirmed in 2 separate populations (Healthy Lifestyle in Europe by Nutrition in Adolescence study and European Youth Heart Study), with 2 different methods to assess EI, and using 4 different methods to assess adiposity. These findings were already shown by others.3 Dr Rey-L
opez is also concerned about the method used to estimate EE. We used accelerometry to assess physical activity intensity-levels and its primary role in the study was not to estimate EE, but to examine its relationship with EI. Our results support the hypothesis1 that more physically active and leaner adolescents have higher EI than less active adolescents with larger amounts of fat mass. Interestingly, these findings persisted after the group of youth who presumably underreport EI was excluded from the analysis. These observational findings should be replicated in welldesigned intervention studies. We need to analyze the data and report them objectively to enhance our understanding of why some youths develop healthier body compositions than others.

Magdalena Cuenca-Garc
ıa, PhD Department of Medical Physiology School of Medicine Granada University Francisco B. Ortega, PhD Jonatan R. Ruiz, PhD Promoting Fitness and Health through Physical Activity (PROFITH) Research Group Department of Physical Education and Sport Faculty of Sport Sciences Granada University 945