Agreement between BMI and body fat obesity definitions in a physically active population
ABSTRACT Objectives Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physic...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Brazilian Society of Endocrinology and Metabolism
2016-11-01
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| Series: | Archives of Endocrinology and Metabolism |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2359-39972016000600515&lng=en&tlng=en |
| _version_ | 1818557895001767936 |
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| author | Luiz Guilherme G. Porto Rosenkranz M. Nogueira Eugênio C. Nogueira Guilherme E. Molina Andrea Farioli Luiz Fernando Junqueira Jr. Stefanos N. Kales |
| author_facet | Luiz Guilherme G. Porto Rosenkranz M. Nogueira Eugênio C. Nogueira Guilherme E. Molina Andrea Farioli Luiz Fernando Junqueira Jr. Stefanos N. Kales |
| author_sort | Luiz Guilherme G. Porto |
| collection | DOAJ |
| description | ABSTRACT Objectives Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physically active population. Subjects and methods 3,822 military firefighters underwent a physical fitness evaluation including cardiorespiratory fitness (CRF) by the 12 min-Cooper test, abdominal strength by sit-up test (SUT) and body composition (BC) by BF% (as the reference), as well as BMI. Obesity was defined by BF% > 25% and BMI ≥ 30 kg/m2. Agreement was evaluated by sensitivity and specificity of BMI, positive and negative predictive values (PPV/NPV), positive and negative likelihood (LR+/LR-), receiver operating characteristic (ROC) curves and also across age, CRF and SUT subgroups. Results The prevalence of obesity estimated by BMI (13.3%) was similar to BF% (15.9%). Overall agreement was high (85.8%) and varied in different subgroups (75.3-94.5%). BMI underestimated the prevalence of obesity in all categories with high specificity (≥ 81.2%) and low sensitivity (≤ 67.0). All indices were affected by CRF, age and SUT, with better sensitivity, NPV and LR- in the less fit and older groups; and higher specificity, PPV and LR+ among the fittest and youngest groups. ROC curves showed high area under the curve (≥ 0.77) except for subjects with CRF ≥ 14 METs (= 0.46). Conclusion Both measures yielded similar obesity prevalences, with high agreement. BMI did not overestimate obesity prevalence. BMI ≥ 30 was highly specific to exclude obesity. Because of systematic under estimation, a lower BMI cut-off point might be considered in this population. |
| first_indexed | 2024-12-14T00:05:41Z |
| format | Article |
| id | doaj.art-b234ab64224e4f15911792e1f587c24f |
| institution | Directory Open Access Journal |
| issn | 2359-4292 |
| language | English |
| last_indexed | 2024-12-14T00:05:41Z |
| publishDate | 2016-11-01 |
| publisher | Brazilian Society of Endocrinology and Metabolism |
| record_format | Article |
| series | Archives of Endocrinology and Metabolism |
| spelling | doaj.art-b234ab64224e4f15911792e1f587c24f2022-12-21T23:26:04ZengBrazilian Society of Endocrinology and MetabolismArchives of Endocrinology and Metabolism2359-42922016-11-0160651552510.1590/2359-3997000000220S2359-39972016000600515Agreement between BMI and body fat obesity definitions in a physically active populationLuiz Guilherme G. PortoRosenkranz M. NogueiraEugênio C. NogueiraGuilherme E. MolinaAndrea FarioliLuiz Fernando Junqueira Jr.Stefanos N. KalesABSTRACT Objectives Body mass index (BMI) is a widely used proxy of body composition (BC). Concerns exist regarding possible BMI misclassification among active populations. We compared the prevalence of obesity as categorized by BMI or by skinfold estimates of body fat percentage (BF%) in a physically active population. Subjects and methods 3,822 military firefighters underwent a physical fitness evaluation including cardiorespiratory fitness (CRF) by the 12 min-Cooper test, abdominal strength by sit-up test (SUT) and body composition (BC) by BF% (as the reference), as well as BMI. Obesity was defined by BF% > 25% and BMI ≥ 30 kg/m2. Agreement was evaluated by sensitivity and specificity of BMI, positive and negative predictive values (PPV/NPV), positive and negative likelihood (LR+/LR-), receiver operating characteristic (ROC) curves and also across age, CRF and SUT subgroups. Results The prevalence of obesity estimated by BMI (13.3%) was similar to BF% (15.9%). Overall agreement was high (85.8%) and varied in different subgroups (75.3-94.5%). BMI underestimated the prevalence of obesity in all categories with high specificity (≥ 81.2%) and low sensitivity (≤ 67.0). All indices were affected by CRF, age and SUT, with better sensitivity, NPV and LR- in the less fit and older groups; and higher specificity, PPV and LR+ among the fittest and youngest groups. ROC curves showed high area under the curve (≥ 0.77) except for subjects with CRF ≥ 14 METs (= 0.46). Conclusion Both measures yielded similar obesity prevalences, with high agreement. BMI did not overestimate obesity prevalence. BMI ≥ 30 was highly specific to exclude obesity. Because of systematic under estimation, a lower BMI cut-off point might be considered in this population.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2359-39972016000600515&lng=en&tlng=enBody compositionfirefighterscardiorespiratory fitnesssensitivityspecificityBMIbody fat |
| spellingShingle | Luiz Guilherme G. Porto Rosenkranz M. Nogueira Eugênio C. Nogueira Guilherme E. Molina Andrea Farioli Luiz Fernando Junqueira Jr. Stefanos N. Kales Agreement between BMI and body fat obesity definitions in a physically active population Archives of Endocrinology and Metabolism Body composition firefighters cardiorespiratory fitness sensitivity specificity BMI body fat |
| title | Agreement between BMI and body fat obesity definitions in a physically active population |
| title_full | Agreement between BMI and body fat obesity definitions in a physically active population |
| title_fullStr | Agreement between BMI and body fat obesity definitions in a physically active population |
| title_full_unstemmed | Agreement between BMI and body fat obesity definitions in a physically active population |
| title_short | Agreement between BMI and body fat obesity definitions in a physically active population |
| title_sort | agreement between bmi and body fat obesity definitions in a physically active population |
| topic | Body composition firefighters cardiorespiratory fitness sensitivity specificity BMI body fat |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S2359-39972016000600515&lng=en&tlng=en |
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