Weight loss and serum lipids in overweight and obese adults: A systematic review and meta-analysis

Background: Excess adipose tissue is associated with an abnormal lipid profile that may improve with weight reduction. In this meta-analysis, we aimed to estimate the magnitude of change in lipid parameters associated with weight loss in adults who are overweight or obese. Methods: We searched MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, and Scopus from 2013 to September, 2018. We included randomized controlled trials (RCTs) that evaluated interventions to treat adult obesity (lifestyle, pharmacologic and surgical) with follow-up of 6 months or more. Results: We included 73 RCTs with moderate-to-low risk of bias, enrolling 32 496 patients (mean age, 48.1 years; weight, 101.6 kg; and body mass index [BMI], 36.3 kg/m2). Lifestyle interventions (diet, exercise, or both), pharmacotherapy, and bariatric surgery were associated with reduced triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) concentrations and increased high-density lipoprotein cholesterol (HDL-C) at 6 and 12 months. The following data are for changes in lipid parameters after 12 months of the intervention with 95% CI. Following lifestyle interventions, per 1 kg of weight lost, TGs were reduced by -4.0 mg/dL (95% CI, -5.24 to -2.77 mg/dL), LDL-C was reduced by -1.28 mg/dL (95% CI, -2.19 to -0.37 mg/dL), and HDL-C increased by 0.46 mg/dL (95% CI, 0.20 to 0.71 mg/dL). Following pharmacologic interventions, per 1 kg of weight lost, TGs were reduced by -1.25 mg/dL (95% CI, -2.94 to 0.43 mg/dL), LDL-C was reduced by -1.67 mg/dL (95% CI, -2.28 to -1.06 mg/dL), and HDL-C increased by 0.37 mg/dL (95% CI, 0.23 to 0.52 mg/dL). Following bariatric surgery, per 1 kg of weight lost, TGs were reduced by -2.47 mg/dL (95% CI, -3.14 to -1.80 mg/dL), LDL-C was reduced by -0.33 mg/ dL (95% CI, -0.77 to 0.10 mg/dL), and HDL-C increased by 0.42 mg/dL (95% CI, 0.37 to 0.47 mg/dL). Low-carbohydrate diets resulted in reductions in TGs and increases in HDLC, whereas low-fat diets resulted in reductions in TGs and LDL-C and increases in HDL-C. Results were consistent across malabsorptive and restrictive surgery. Conclusions: Weight loss in adults is associated with statistically significant changes in serum lipids. The reported magnitude of improvement can help in setting expectations, inform shared decision making, and facilitate counseling.