The present invention provides a new composition, food product and uses for a known compound. More particularly, the present invention provides a new pharmaceutical composition containing 3-guanidinopropionic acid and a method of using 3-guanidinopropionic acid to prevent or treat obesity in non-insulin dependent diabetic (NIDDM) patients that is caused by treatment with anti-diabetic drugs, such as an insulin sensitizing drug or an insulin secretion stimulating drug. Examples of insulin sensiti...