Eric Yan

University of California, Los Angeles, Los Angeles, California, United States

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Publications (8)14.49 Total impact

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    ABSTRACT: Obesity prevalence and average body composition vary by US race and gender. Asian Americans have the lowest prevalence of obesity. Relying on body-mass index (BMI) to estimate obesity prevalence may misclassify subgroups that appear normally weighted but have excess body fat. We evaluated percentage body fat (PBF) and BMI to determine whether BMI reflects PBF consistently across different races. 940 college students were recruited from a local public university over four consecutive years. We measured PBF by bioelectrical impedance analysis (BIA), weight by physicians' scales, and height with stadiometers. Our sample comprised Asians (49%), Caucasians (23%), Hispanics (7%), and Other (21%). Participants averaged 21.4 years old; BMI was 22.9 kg/m(2); PBF was 24.8%. BMI and PBF varied significantly by race and gender (P value = 0.002 and 0.005 for men; 0.0009 and 0.0008 for women). Asian-American women had the lowest BMI (21.5 kg/m(2)) but the second highest PBF (27.8%). Linear association between BMI and PBF was the weakest (r (2) = 0.09) among Asian-American women and BMI had the poorest sensitivity (37%) to detect PBF. The high PBF with low BMI pattern exhibited by Asian-American women suggests that they could escape detection for obesity-related disease if BMI is the sole measure that estimates body composition.
    Journal of obesity 01/2013; 2013:790654.
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    ABSTRACT: There is concern that recommending protein-enriched meal replacements as part of a weight management program could lead to changes in biomarkers of liver or renal function and reductions in bone density. This study was designed as a placebo-controlled clinical trial utilizing two isocaloric meal plans utilizing either a high protein-enriched (HP) or a standard protein (SP) meal replacement in an outpatient weight loss program. 100 obese men and women over 30 years of age with a body mass index (BMI) between 27 to 40 kg/m2 were randomized to one of two isocaloric weight loss meal plans 1). HP group: providing 2.2 g protein/kg of lean body mass (LBM)/day or 2). SP group: providing 1.1 g protein/kg LBM/day. Meal replacement (MR) was used twice daily (one meal, one snack) for 3 months and then once a day for 9 months. Body weight, lipid profiles, liver function, renal function and bone density were measured at baseline and 12 months. Seventy subjects completed the study. Both groups lost weight (HP -4.29 ± 5.90 kg vs. SP -4.66 ± 6.91 kg, p < 0.01) and there was no difference in weight loss observed between the groups at one year. There was no significant change noted in liver function [AST (HP -2.07 ± 10.32 U/L, p = 0.28; SP 0.27 ± 6.67 U/L, p = 0.820), ALT (HP -1.03 ± 10.08 U/L, p = 0.34; SP -2.6 ± 12.51 U/L, p = 0.24), bilirubin (HP 0.007 ± 0.33, U/L, p = 0.91; SP 0.07 ± 0.24 U/L, p = 0.120), alkaline phosphatase (HP 2.00 ± 9.07 U/L, p = 0.240; SP -2.12 ± 11.01 U/L, p = 0.280)], renal function [serum creatinine (HP 0.31 ± 1.89 mg/dL, p = 0.380; SP -0.05 ± 0.15 mg/dL, p = 0.060), urea nitrogen (HP 1.33 ± 4.68 mg/dL, p = 0.130; SP -0.24 ± 3.03 mg/dL, p = 0.650), 24 hour urine creatinine clearance (HP -0.02 ± 0.16 mL/min, p = 0.480; SP 1.18 ± 7.53 mL/min, p = 0.400), and calcium excretion (HP -0.41 ± 9.48 mg/24 hours, p = 0.830; SP -0.007 ± 6.76 mg/24 hours, p = 0.990)] or in bone mineral density by DEXA (HP 0.04 ± 0.19 g/cm2, p = 0.210; SP -0.03 ± 0.17 g/cm2, p = 0.320) in either group over one year. These studies demonstrate that protein-enriched meals replacements as compared to standard meal replacements recommended for weight management do not have adverse effects on routine measures of liver function, renal function or bone density at one year.
    Nutrition Journal 12/2010; 9:72. · 2.64 Impact Factor
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    ABSTRACT: While high protein diets have been shown to improve satiety and retention of lean body mass (LBM), this study was designed to determine effects of a protein-enriched meal replacement (MR) on weight loss and LBM retention by comparison to an isocaloric carbohydrate-enriched MR within customized diet plans utilizing MR to achieve high protein or standard protein intakes. Single blind, placebo-controlled, randomized outpatient weight loss trial in 100 obese men and women comparing two isocaloric meal plans utilizing a standard MR to which was added supplementary protein or carbohydrate powder. MR was used twice daily (one meal, one snack). One additional meal was included in the meal plan designed to achieve individualized protein intakes of either 1) 2.2 g protein/kg of LBM per day [high protein diet (HP)] or 2) 1.1 g protein/kg LBM/day standard protein diet (SP). LBM was determined using bioelectrical impedance analysis (BIA). Body weight, body composition, and lipid profiles were measured at baseline and 12 weeks. Eighty-five subjects completed the study. Both HP and SP MR were well tolerated, with no adverse effects. There were no differences in weight loss at 12 weeks (-4.19 +/- 0.5 kg for HP group and -3.72 +/- 0.7 kg for SP group, p > 0.1). Subjects in the HP group lost significantly more fat weight than the SP group (HP = -1.65 +/- 0.63 kg; SP = -0.64 +/- 0.79 kg, P = 0.05) as estimated by BIA. There were no significant differences in lipids nor fasting blood glucose between groups, but within the HP group a significant decrease in cholesterol and LDL cholesterol was noted at 12 weeks. This was not seen in the SP group. Higher protein MR within a higher protein diet resulted in similar overall weight loss as the standard protein MR plan over 12 weeks. However, there was significantly more fat loss in the HP group but no significant difference in lean body mass. In this trial, subject compliance with both the standard and protein-enriched MR strategy for weight loss may have obscured any effect of increased protein on weight loss demonstrated in prior weight loss studies using whole food diets.
    Nutrition Journal 09/2008; 7:23. · 2.64 Impact Factor
    This article is viewable in ResearchGate's enriched format
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    ABSTRACT: Roux-en-Y gastric bypass patients often undergo preoperative dieting and psychological assessment before surgery. We examined preoperative weight loss, binge eating disorder (BED), and sexual abuse history and the interactions of these predictors to determine whether a cautionary approach to Roux-en-Y gastric bypass is warranted. Consecutive subjects undergoing Roux-en-Y gastric bypass at our institution from January 1997 to December 2002 were reviewed. The postoperative excess weight loss (EWL) at 1, 3, 6, 12, 18, and 24 months and the perioperative complications were measured. EWL was compared at 12 and 24 months postoperatively in the categories of the presence/absence of preoperative weight loss, BED, and sexual abuse history. The perioperative complications were examined in the preoperative weight change groups. Of 154 patients, 121 were included. No significant difference in EWL or perioperative complications was observed between those who lost or gained weight preoperatively. Of the 121 patients, 32% and 17% reported a history of BED and sexual abuse, respectively. No statistically significant difference was observed in the EWL between those with and without BED at 12 and 24 months postoperatively. The EWL in those with and without a sexual abuse history at 12 and 24 months was 57.67% and 66.32% (P <.05) and 64.40% and 70.97% (P = NS). No statistically significant interaction between EWL and sexual abuse*BED/sexual abuse*preoperative weight loss was observed. Only sexual abuse history at postoperative month 12 had a negative effect on EWL. Otherwise, physicians can expect to see successful EWL in these subjects up to 24 months postoperatively. We recommend that additional investigation be done of those with BED and a sexual abuse history.
    Surgery for Obesity and Related Diseases 03/2008; 4(2):137-43. · 4.94 Impact Factor
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    ABSTRACT: Various adipose tissue factors have been implicated as biomarkers of the metabolic syndrome (MS). The objective of this study was to assess which specific adipose tissue factors would discriminate the presence of MS in a strictly obese population meeting waist circumference (WC) criteria for the MS. This was a cross-sectional study of 148 subjects recruited from a university-based weight loss program prior to starting the program. Patients were eligible if they had a BMI more than 25 kg/m(2) and had WC more than 40 and 35 inches in males and females, respectively. Biomarkers measured included high sensitivity C-reactive protein (hs-CRP), leptin, adiponectin, and total insulin. Of the total population, 33.8% satisfied criteria for the MS. Insulin was the only biomarker to consistently differentiate between presence and absence of MS in this obese population (P = 0.0001 in males, P = 0.006 in females). All biomarkers measured with the exception of leptin had a statistically significant relationship with increasing criteria for the MS. In a population where an excess amount of adipose tissue exists, insulin is the only reliable biomarker to differentiate MS status. We surmise that differences in hs-CRP, leptin, and adiponectin are a reflection of their measurements in individuals with statistically different amounts of adipose tissue.
    Metabolic syndrome and related disorders 02/2008; 6(1):64-73. · 1.92 Impact Factor
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    ABSTRACT: Long-term results of Roux-en-Y gastric bypass (RYGB) are nonexistent in the veterans affairs (VA) population. We compare excess weight loss (EWL) success and medical comorbidity changes between the VA and non-VA population after RYGB. Retrospective review of consecutive subjects undergoing RYGB from 1997 to 2002 at the Los Angeles VA. Weight and comorbidity data were collected every 6 and 12 months, respectively. Fifty-nine subjects were included; 54%, 58%, 46.8%, and 44.1% of subjects achieved EWL >50% at years 1 to 4. Hypertension resolved in 23%, 30%, and 32% at months 12 to 36. Obstructive sleep apnea resolved in 37%, 48%, 48%, 44%, and 60% at months 12 to 60. Diabetes mellitus resolved in 86%, 84%, 79%, and 80% at months 12 to 48. Improvements in the lipid panel were observed by month 12 and maintained thereafter. EWL and proportion of subjects with resolved hypertension and obstructive sleep apnea are inferior to the non-VA population. Nevertheless, improvements in measures of success are maintained in the VA population.
    American journal of surgery 01/2008; 195(1):94-8. · 2.36 Impact Factor
  • Obesity Management 06/2007; 3(3):115-120.
  • Steve Chen, Eric Yan
    Obesity Management 02/2006; 2(1):31-32.