The invention relates to a method for treating overweight persons or patients with obesity using a food composition able to control the release of glucose into the patient's blood. This is achieved by the introduction into the food composition of a therapeutically effective amount of an additive, such as propylene glycol alginate (PGA) or other hydrophilic agent or pharmaceutically acceptable salts thereof, which reduces the cooking losses and enhances the starch cell wall membrane to thereby slow the enzymatic hydrolysis of the starch by insulin. The result is a steady state release of glucose and a net reduction in the release of blood glucose (glycemic index) relative to release of glucose observed in an overweight or obese patient having consumed a food composition without propylene glycol alginate, whereby the patient experiences a loss in body weight.