This report describes the case of a postmenopausal, White female of normal weight with a history of idiopathic dyslipidemia. She presented with high systolic blood pressure, total cholesterol, low-density lipoprotein cholesterol, and lipoprotein(a) [Lp(a)]—an independent and causal risk factor for atherosclerotic cardiovascular diseases—despite eating an exclusively whole-plant-food diet free of added salt, oil, and sugar (SOS-free) and adhering to other health-promoting practices for the past 40 years. The patient undertook a remotely administered, five-day water-only fast, and six weeks later demonstrated clinically meaningful improvements in cardiometabolic markers; notably, her blood pressure normalized and Lp(a) dropped by -32.5%, even with negligible body weight loss. These results provide a preliminary observation that prolonged water-only fasting may influence Lp(a) levels, beyond those gained from eating a whole-plant-food diet and healthy lifestyle, particularly for genetic or idiopathic cardiovascular abnormalities. Keywords: lipoprotein(a), water-only fasting, whole-plant-food diet, cardiometabolic risk, postmenopausal, case report