Drinking milk while eating helps one lose weight because milk helps to decrease the glycemic index (GI), an indicator of the rate and quantity of sugar that comes into blood.
A food's GI can affect people's weight when consuming food, contrary to the common belief that it is the calories contained in food that pack on the pounds. Rather, calories are only linked to energy generation. A lower GI means less fat is stored in the body, thus contributing to weight loss. Assuming some foods have the same calorie content, the lower the GI is, the more effective it is for weight loss.
According to a report released by Japan's National Institute of Public Health, the GI of boiled rice with dried seaweed was 94, but when a glass of milk is added, with total calories unchanged, the index decreased by approximately 37 percent to 59.
Similar results occurred when reducing the intake of white bread by 20 percent and drinking 100 ml of milk instead. However, excessive milk consumption is not recommended either because milk contains fat. Kang Jae-heon, a family medicine doctor at Inje University Seoul Paik Hospital, recommends drinking low-fat milk if one drinks milk regularly.