Skeletal myopathy, although foreseeable in severe malnutrition, has been rarely reported in patients with anorexia nervosa. We report a case of oculo-oropharyngeal myopathy mimicking myasthenia in a 42-year-old woman with an history of anorexia nervosa, completely reversible after refeeding with carbohydrate diet, mainly chocolate. Nutritional myopathies are not well known and therefore rarely looked for in patients with anorexia nervosa. Classical presentation is a myogenic syndrome with severe type 2 fibre atrophy and biochemical characteristics similar to Mac Ardle's disease. A clinical form mimicking myasthenia gravis has never been reported. Refeeding programme leads to total recovery within a few days.