Complex sentence: Left untreated, compulsive overeating can lead to serious medical conditions including high cholesterol, diabetes, heart disease, hypertension, sleep apnea, and major depression.
Split into simpler sentences: Left untreated, compulsive overeating can lead to serious medical conditions. In addition, compulsive overeating could potentially lead to high cholesterol, diabetes, heart disease, hypertension, sleep apnea, and major depression.