A leading contributor of science and knowledge through discoveries.
Cardiorespiratory Fitness and Adiposity in Metabolically Healthy Overweight and Obese Youth
Martin Sénéchal, PhD, Brandy Wicklow, MD, Kristy Wittmeier, PhD, Jacqueline Hay, MS, Andrea C. MacIntosh, BA, Pinar Eskicioglu, BSc, Niranjan Venugopal, PhD, and Jonathan M. McGavock, PhD, 2013
Obesity is associated with an array of risk factors such as insulin resistance, metabolic syndrome, and fatty liver disease that increase a child s risk for Type 2 diabetes and heart disease. While it is commonly believed that all overweight individuals have these risk factors, 25 to 40% obese adults remain free from cardiometabolic risk factors and are considered “metabolically healthy”. These “Metabolically Healthy Obese” (MHO) individuals have a lower risk for developing debilitating diseases and live longer than peers with metabolic diseases. The purpose of this study was to address two important gaps in our understanding of metabolically healthy obesity in children: (1) In a community-based sample of overweight or obese youth, how many would be considered metabolically healthy? and (2) How important is fitness in determining whether an overweight child is metabolically healthy?
To answer these questions, we conducted a series of cross-sectional and matching studies comparing fitness levels between overweight children with metabolic risk factors and those without risk factors. Risk factors that we measured in the children included high blood pressure, high bad cholesterol, low good cholesterol, fatty liver and blood sugar. Fitness levels were measured on a stationary bike test where children pedaled and increasing workloads until maximal exhaustion. Fatty liver was measuring using a very novel MRI technique that provided an accurate but non-invasive measure of how much fat was in their liver.
First, we found that over 30% of overweight and obese children do not have a single elevated metabolic risk factor. The children without any risk factors were characterized by a lower body weight and lower levels of fat in their liver. Second, we found that being metabolically healthy had nothing to do with fitness levels. In fact when children were separated into categories of very high fitness and low fitness, the number of children that were metabolically healthy in each group was identical. Therefore, fitness levels were not an important predictor of being metabolically healthy in obese children.
This study provides important insight into the predictors of metabolic disease in obese youth. For clinicians and parents, they should be aware that in overweight children can be risk free and that it is relatively common. Additionally, the important predictor of being free from metabolic risk factors is preventing excessive weight gain.
Allison B. Dart, MD, Elizabeth A. Sellers, MD, Patricia J. Martens, PHD, Claudio Rigatto, MD, Marni D. Brownell, PHD and Heather J. Dean, MD
Azad MB, Bridgman SL, Becker AB, Kozyrskyj AL