Normal-weight obesity in adolescents: a hidden problem

Normal-weight obesity is defined by the presence of normal weight according to the BMI, together with excess body fat. Although it is well recognized in the literature about the complications associated with BMI-defined obesity, few studies have evaluated normal-weight obesity in adolescents.

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Background:

Obesity is one of the main public health problems faced today, which is associated with the development of numerous other diseases and metabolic complications. The Body Mass Index (BMI) is used in most studies and in clinical practice to diagnose the nutritional status of individuals. Although it has numerous advantages, such as low cost and speed, the use of BMI has limitations, since it is an index based on measurements of total body weight and height. Thus, BMI does not differentiate between muscle, bone and fat mass.

In this context, phenotypes of obesity that affect individuals with normal weight have been studied, such as the normal weight obesity [1]. Few studies have evaluated this phenotype in adolescents [2] and this represents an important gap, since the presence of adolescents with the phenotype can often be underdiagnosed because they do not present visible changes in the body. Furthermore, it is still not entirely clear in the literature about the possibility of an elevated cardiometabolic risk in adolescents who manage to maintain their weight within the normal range by BMI.

What did we find out?

Our manuscript, entitled "Cardiometabolic risk in adolescents with normal weight obesity" [3], describes a survey of 506 normal weight adolescents, aged 10 to 19 years, of both sexes, who had their body composition assessed by dual-energy X-ray absorptiometry (DXA). We divided the adolescents into two groups: with normal-weight obesity and without normal-weight obesity. We found that among the components of the metabolic syndrome, the prevalence of the normal-weight obesity phenotype was higher among participants with abdominal obesity and altered blood glucose. Furthermore, we observed a positive association of normal weight obesity with cardiometabolic risk factors, such as abdominal obesity, android fat, insulin resistance, higher values of the triglyceride-glycemia (TyG) index, uric acid, hyperinsulinemia, and insulin resistance, as well as to alterations in LDL, total cholesterol, and to the presence of a greater number of alterations in the components of the metabolic syndrome.

Considering the scarcity of studies with adolescents on this subject, we emphasize that our results bring new knowledge to the literature. In this sense, we emphasize, based on our results, that only normal BMI does not protect adolescents against cardiometabolic risks. Thus - especially when considering that the presence of the phenotype may be overlooked due to young age and normal body weight - we highlight the importance of early detection in order to prevent future diseases. Moreover, we emphasize possible needs to reformulate outpatient care and public education and health policies - which are mostly based on individuals with obesity by BMI.

Link to the article: 

Cota, B.C., Priore, S.E., Ribeiro, S.A.V. et al. Cardiometabolic risk in adolescents with normal weight obesity. Eur J Clin Nutr (2021). https://doi.org/10.1038/s41430-021-01037-7

https://www.nature.com/articles/s41430-021-01037-7#citeas

References:

[1] De Lorenzo A, Martinoli R, Vaia F, et al. (2006) Normal weight obese (NWO) women: an evaluation of a candidate new syndrome. Nutr Metab Cardiovasc Dis 16, 513–523.

[2] Cota BC, Suhett LG, Leite NN, et al. (2021) Cardiometabolic Risk and Health Behaviors in Adolescents with Normal Weight Obesity: A Systematic Review. Public Health Nutrition, Apr;24(5):870-881.

[3] Cota, B.C., Priore, S.E., Ribeiro, S.A.V. et al. Cardiometabolic risk in adolescents with normal weight obesity. Eur J Clin Nutr (2021). https://doi.org/10.1038/s41430-021-01037-7

Bruna

PhD student, Federal University of Viçosa

Nutritionist from the Federal University of Viçosa (UFV, 2019), Master in Nutrition Science (UFV, 2021) and PhD student in Nutrition Science at the Federal University of Viçosa. Member of the research group "Pesquisa de Avaliação da Saúde do Escolar (PASE)" - School Health Evaluation Survey (PASE study).