Obesity, hyperlipidemia, and non-insulin-dependent diabetes seem to share common causative factors, chemical abnormalities, and clinical complications. A positive energy balance requiring storage of excess nutrients as triglyceride appears to be an underlying factor in all. It is postulated that everyone has a defined capacity to store triglyceride. Filling the storage space from plasma glucose and triglyceride is insulin dependent. When storage areas are full, the effectiveness of insulin is reduced, and excess nutrients stay in circulation, producing the clinical picture of hyperlipidemia, non-insulin-dependent diabetes, and the shared findings. Comments about the implications of the model for the treatment of hypercholesterolemia, hypertriglyceridemia, and non-insulin-dependent diabetes are also incorporated.