PSUN55 Abnormal Body Fat Distribution in Lean Individuals with Metabolic Abnormalities
Authors: Badour Sanaa , Valderrãbano Rodrigo , Ferri-Guerra Juliana , Barb Diana , Garg Rajesh 
Published: November 2022

Abstract

Background
Truncal obesity has long been considered an essential driver of metabolic abnormalities, but it is common for lean individuals with body mass index (BMI) &lt;25 kg/m2 to have one or more metabolic abnormalities. We hypothesized that metabolically unhealthy lean (MUL) individuals have a different distribution of fat compared to their metabolically healthy lean (MHL) counterparts.

Methods
We performed a retrospective analysis of body composition data obtained from a repository of dual-energy X-ray absorptiometry scans performed during routine clinical practice at a University Bone Clinic. Metabolic data were retrieved from electronic medical records within one calendar year of the index scan. Those with at least 2 components of the metabolic syndrome: blood pressure &gt;130/85 mmHg, triglyceride &gt;150 mg/dL, HDL &lt;50 mg/dL for women and &lt;40 mg/dL for men, fasting plasma glucose &gt;100 mg/dL (or HbA1c &gt;5.7) were considered MUL, while those with 1 component or less were considered MHL. Waist circumference was not considered in this study. Adults with a BMI less than 25 kg/m2 were included in the analysis. Unadjusted and adjusted binary logistic regression were used to analyze the association between metabolic abnormalities and various anthropometric indexes.

Results
The study population consisted of 119 lean adults with a mean age of 62±14 years and a mean BMI of 22±1.9 kg/m2. Majority of participants were white (88%, n=105) and included postmenopausal women (85%, n=101). A large proportion were of Hispanic ethnicity (41%, n=70). There were 69 (58%) MHL and 50 (42%) MUL individuals. MUL and MHL groups had comparable percentage of total body fat (34±6.6 versus 34±5.6, p=0.360), fat mass index (8.2±1.6 versus 8.1±1.5, p=0.360) and appendicular lean mass (kg/m2) (5.9±0.8 versus 5.8±0.7, p=0.420). However, compared to MHL, MUL subjects had significantly higher visceral adipose tissue (cm2) (87±40 versus 9±29, p=0.004), trunk-to-leg fat ratio (0.89±0.18 versus 0.77±0.13, p&lt;0.001), trunk-to-limb fat ratio (1.00±0.29 versus 0.82±0.18, p&lt;0.001) and android-to-gynoid fat ratio (0.90±0.16 versus 0.81±0.15, p=0.010). After adjusting for age and sex, the odds of being MUL compared to MHL (odds ratio [OR (95% confidence interval (CI))]) increased for every standard deviation increase in visceral adipose tissue (OR=1.75 [1.13-2.73]), trunk-to-leg fat ratio (OR=2.28 [1.30-4.00]), trunk-to-limb fat ratio (OR=2.43 [1.37-4.32]) and android-to-gynoid fat ratio (OR=1.80 [1.07-3.03]).

Conclusion
Metabolically unhealthy subjects with normal BMI had markedly increased visceral adipose tissue and truncal redistribution of body fat without an increase in total body fat. These findings highlight the importance of using body morphometry measures, rather than total body fat, to assess CVD risk in lean individuals. Our findings suggest that the phenotype of lean individuals with metabolic derangements is not very different from that of obese individuals who have metabolic syndrome as per the National Cholesterol Education Program Adult Treatment Panel-III definition.
Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.