Background: A female carrying the common MERRF mitochondrial DNA A8344G mutation had multiple symmetric lipomatosis (MSL) as the primary disease manifestation. Methods: Case report of a mitochondrial disease patient treating her severe lipomas by lifestyle modifications including a modified ketogenic diet. Results: The patient required lipoma reduction surgery after a rapid rate of lipoma progression. Following a difficult recovery, the patient independently researched an alternative therapy for her disease. The intervention was multi-faceted (dietary, physical activity, meditation) and progressive over two years. A carbohydrate reduced (5–10% of calories) modified ketogenic diet was a major part of the treatment owing to its incidental success in MSL management in her brother for management of glioblastoma multiforme. The outcome of her intervention was positive: weight loss, lipoma size reduction, improvement in physical activity/strength, laboratory markers of insulin resistance, and sense of well including a return to full time work. Conclusions: A potential non-surgical therapy for mitochondrial disease associated MSL appears feasible over the short term. The success of the lifestyle intervention in MSL therapy is unprecedented and, importantly, was fully patient initiated. This novel therapy provides potential insight into the mechanism of MSL exacerbation: suggesting insulin resistance or other lifestyle modifiable factors as mediators of disease progression.