Background: South Asians (SA) have high rates of NAFLD. SA adults have NAFLD at lower BMI. We examined differences in ectopic fat between SA and White (W) youth, and its relationship to BMI z-score (BMIZ) , fat depots, and metabolic labs.
Methods: SA and W youth, 12-21y, BMI ≥ 80%ile (or ≥23kg/m2 if ≥18y) underwent MRS to measure liver fat and intramyocellular lipid (IMCL) (soleus) , and DXA to quantify total % body fat (%BF) and lean mass (LM) . Abdominal MRI was used to measure abdominal fat (AF) , visceral fat (VF) , SQ fat, deep SQ, and superficial SQ. HbA1c, fasting glucose (FBG) , and lipids were obtained. Univariate analyses used parametric or non-parametric methods as appropriate. Linear regression adjusted for potential confounding variables. NAFLD defined as >5% liver fat.
Results: Participants (28 SA, 9 W) had similar age, sex, and BMIZ. Liver fat was higher in SA [2.0% (1.1, 7.4) ] compared to W [0.8% (0.7, 1.4) ], but not statistically different. NAFLD was present in 29% of SA youth, but in no W youth. There was no difference in IMCL (p=0.9) or VF between groups (p=0.5) . Adjusting for age, sex, puberty and BMIZ, SA had lower LM [β= -8.1, p=0.003] and higher %BF [β=5.8, p=0.01], AF [β=151.6, p=0.006], total SQ fat [β=65.9, p=0.001], deep SQ fat [β=1.9, p=0.005] and HbA1c [β=3.8, p=0.01] than W. FBG and lipids were similar between groups. In SA, liver fat correlated with HDL-C (p=0.02) , LDL-C (p=0.03) , non-HDL-C (p=0.03) and borderline with FBG (p=0.05) , HbA1c (p=0.06) , but not with BMIZ, LM, %BF, or triglycerides. In SA, VF was correlated with triglycerides (p=0.002) and non-HDL-C (p=0.04) and borderline with LM (p=0.05) and HDL-C (p=0.06) .
Conclusions: These preliminary results of an ongoing study demonstrate that 29% of SA youth had NAFLD compared to no W youth. Liver fat in SA youth was not related to typical metabolic risk factors. Notably SA youth had lower LM, and increased AF, deep SQ fat, and HbA1c compared to W youth, after adjustment. Further study is needed to clarify the mechanisms underlying excess liver fat in SA youth.
T.A.Hitt: None. S.C.N.Hui: None. I.R.Kamel: None. P.B.Barker: None. B.S.Zemel: None. A.Kelly: Research Support; vTv Therapeutics. S.N.Magge: None.
National Institutes of Health (R01DK115648)