Emily E. Grammer1, Joshua E. McGee2, Taylor T. Brown2, Marie C. Clunan2, Anna C. Huff2, Briceida G. Osborne2, Laura E. Matarese2, Walter J. Pories2, Joseph A. Houmard, FACSM2, Robert A. Carels2, Mark A. Sarzynski, FACSM3, Damon L. Swift1. 1University of Virginia, Charlottesville, VA. 2East Carolina University, Greenville, NC. 3University of South Carolina, Columbia, SC.

BACKGROUND: Apolipoprotein B (ApoB) is a predictor of cardiovascular disease and may have higher prognostic value compared to traditional lipid risk factors. There is a lack of data on the effects clinically significant weight loss (CWL) (≥7%) on ApoB and how weight maintenance after weight loss alters ApoB. The purpose of this study was to examine the effect on ApoB concentrations after CWL and exercise level during weight maintenance in overweight and obese adults. METHODS: Thirty overweight and obese adults (age: 45.7 [10.7] yrs; BMI: 34.4 [3.4] kg/m2) underwent a 10-week weight-loss intervention followed by 18 weeks of weight maintenance. During the weight loss phase, participants completed a hypocaloric weight-loss program (OPTIFAST) and supervised aerobic exercise. Exercise began at 300 MET min/week and increased by 50 MET min weekly until 700 MET min/week was reached. Participants that achieved CWL were randomized to weight maintenance (WM-REC; 970 MET min/week) or physical activity (PA-REC; 550 MET min/week) groups. Nuclear magnetic resonance (NMR) of plasma was used to assess blood components at baseline, after weight loss, and at follow-up. RESULTS: During the weight loss phase, participants decreased mass (-8.5 kg, p=0.001) and BMI (-3.1 kg/m2, p=0.001). Participants also reduced ApoB (-11.6 mg/dL, p=0.001), low density lipoprotein (LDL) (-8.0 mg/dL, p=0.013), high density lipoprotein (HDL) (-3.2 mg/dL, p=0.013), and TG (-27.2 mg/dL, p=0.001) after weight loss. During the weight maintenance phase, increased ApoB (20.9 mg/dL, p=0.006) and HDL (11.4 mg/dL, p=0.0.003), while LDL and TG did not change (p>0.05). There were no differences between groups in changes in ApoB (WM-REC: 17.0; PA-REC: 23.8 mg/dL), HDL (WM-REC: 9.0; PA-REC: 13.3 mg/dL), LDL (WM-REC: 11.4; PA-REC: 2.4 mg/dL), and TG (WM-REC: 13.4; PA-REC: 1.0 mg/dL) (all ps >0.05) during weight maintenance. Moreover, ApoB was not correlated with body composition or fitness changes in either phase of the study (p>0.05). CONCLUSIONS: ApoB concentrations decreased following weight loss and exercise in obese adults yet increased during weight maintenance. These results indicate that high levels of aerobic exercise did not prevent regression in ApoB after clinically significant weight loss. Future lifestyle-based interventions should investigate nutritional approaches to maintain improvements in ApoB during weight maintenance.

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