Background: Non-alcoholic Fatty Liver Disease (NAFLD), recently renamed Metabolic dysfunction-associated Steatotic Liver Disease (MASLD), is the leading cause of chronic liver disease, contributing significantly to liver-related morbidity and mortality. Evidence indicates that lean individuals exhibit a higher rate of disease progression, liver fibrosis, cardiovascular morbidity, and all-cause mortality in advanced stages compared to obese individuals. Genetic factors significantly influence the prevalence of MASLD. This clinical scenario highlights a unique case of a lean patient with metabolic syndrome and hepatic steatosis, absent hepatic lesions. Case Presentation: An Asian female in her mid-50s, weighing 124 lb, visited her Primary Care Physician (PCP) with complaints of right upper quadrant abdominal pain and bloating after consuming a high-fat diet. She had no vomiting or diarrhea history but reported occasional constipation and elevated systolic blood pressure. Laboratory results indicated borderline elevated HbA1C, high triglycerides, and cholesterol levels. Comprehensive testing, including SIBO, stool tests, H. pylori, anti-HbC, and pancreatic elastase 1, alongside upper and lower GI endoscopy, ultrasonography with elastography, abdominal X-ray, and CT scan, were conducted. Initially misdiagnosed with Functional Bowel Disorder, the patient received treatments for elevated triglycerides, cholesterol, blood glucose, and gastrointestinal (GI) symptoms. After four years of persistent GI symptoms, further diagnostics led to a diagnosis of Lean MASLD with hepatic steatosis but no hepatic lesions. Discussion This case underscores that individuals with a normal BMI can still have abnormal metabolism, hepatic steatosis, and steatohepatitis. Preventing disease progression in such patients is crucial. Despite the rising prevalence and burden of MASLD, effective pharmacotherapy remains limited and evolving. Current treatments focus on addressing metabolic syndrome and promoting weight loss. Evidence supports a weight loss regimen involving a low-carbohydrate, hypocaloric diet aiming for a 30% calorie reduction, or 1200–1500 kcal/day, or a 500–1000 kcal/day reduction from baseline. For lean patients, the goal should be a hypocaloric diet combined with aerobic exercise. The case highlights an opportunity to enhance PCP awareness regarding MASLD, given the initial misdiagnosis of Functional Bowel Disorder. As PCPs and endocrinologists often serve as the first point of contact for MASLD patients in the US, they need to be well-versed in clinical care pathways and evidence-based guidelines to ensure accurate screening, diagnosis, initial management, and timely referrals for at-risk patients.