Mild weight loss promotes plaque growth and synthesis of pro-atherogenic lipids in ApoE-deficient mice fed a high-fat, high-cholesterol diet

Background According to the recent ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease, achieving an initial weight loss of ≥5% over six months in individuals with obesity is associated with clinically meaningful reductions in cardiovascular risk factors. However, emerging evidence suggests that weight loss may paradoxically increase the risk of CVD and atherosclerosis in certain populations. Motivated by these counterintuitive findings, we hypothesized that mild weight loss may induce metabolic reprogramming that promotes atherogenesis, potentially via an upregulation of pro-atherogenic lipids. Methods Apolipoprotein E-deficient mice were fed either a standard Chow or a high-cholesterol/high-fat (HCHF) diet for six months. A subset in each group underwent mild caloric restriction to achieve ∼5% body weight reduction. Atherosclerotic plaque burden in the brachiocephalic artery was assessed histologically. Hepatic lipidomic profiling was conducted via ESI–MS/MS, and lipid changes were compared with published plasma lipidomic data from obese human subjects stratified by CVD and diabetes status. Cardiovascular risk was further evaluated using the ceramide risk score (CERT1). Results Mild weight loss induced significant plaque growth, increasing lesion area by 28% in Chow-fed and 53.8% in HCHF-fed mice relative to controls. In HCHF-fed mice, caloric restriction markedly elevated free cholesterol and multiple pro-atherogenic phospholipids, including nine phosphatidylcholine, six phosphatidylethanolamine, one lysophosphatidylcholine, two sphingomyelin, and three ceramide species. Seven cholesterol esters also increased, and a CERT1 score of 8.1 indicated high CVD risk. These pro-atherogenic lipids were confirmed by comparison with published plasma lipidomic data from CVD and diabetes patients. In contrast, weight loss under Chow conditions caused minimal lipid alterations, with only isolated increases in phosphatidylcholine and lysophosphatidylcholine species. Conclusions Mild weight loss under high-fat dietary conditions accelerates atherosclerosis through increased production of pro-atherogenic lipids. These findings underscore the need to monitor lipidomic responses during weight loss interventions in obese individuals with CVD risk. Graphical Abstract Graphical Abstract model of phospholipid-driven atherosclerosis progression. Graphical summary depicting the mechanistic link between hypercholesterolemia, phospholipid composition, and atherosclerotic plaque development. The left panel highlights pro-atherogenic phospholipids, while the right panel shows anti-atherogenic phospholipids, both grouped by class and correlated with plaque size. Phospholipids enclosed within the dashed box represent those exhibiting statistically significant changes. Highlights Mild weight loss (∼5%) in ApoE-deficient mice fed a high-fat, high-cholesterol diet led to a paradoxical increase in atherosclerotic plaque burden. Weight loss under metabolically adverse dietary conditions may induce pro-atherogenic lipid remodelling that exacerbates atherosclerosis. Careful monitoring of atherogenic lipid species may be warranted in obese patients with existing cardiovascular disease undergoing dietary interventions. Comprehensive, tailored lifestyle interventions—beyond caloric restriction alone—may be necessary to avoid unintended cardiovascular harm during weight loss.