1. GI and Diabetes
Many studies have shown that high-GI foods increase the risk of type 2 diabetes. One large one involving nearly 43,000 healthy men found that a diet of high GI and low-fiber foods did just this. Another study, of more than 65,173 healthy women, confirmed that having a high-GI diet and a low fiber intake increases diabetes risk. This one suggests that diabetes could be reduced in the U.S. if people ate more whole grains.
A large study of 14 previous studies with 356 diabetic patients clearly showed that the low-GI diet improved both the short- and long-term control of blood sugar in diabetics. This one showed that a low-GI diet could work just as well or better than diabetes medications.
There isn’t much doubt that, to reduce your risk of diabetes, or help treat the condition, eating more low-GI foods can work. Other studies have found that these foods could lower cholesterol and reduce other risk factors for heart disease in people who have diabetes.
2. GI and Obesity
A typical Western diet is high in carbs and high-GI foods, with potatoes, breads and low-fat cereals. These are digested and absorbed quickly, putting intense demand on insulin. Low-GI foods control weight better by making you feel full and burning through more fat. They do this by being digested and absorbed slowly, causing a slower rise in glucose and insulin in the blood.
It’s been claimed that a 50% increase in the GI of a meal (e.g. from 50 to 75) will lead to a 50% decrease in the sense of feeling full. In a big trial, researchers showed that 16 out of 17 studies confirmed that low-GI diets increase make you feel fuller. Better and larger studies are still needed to see if a low-GI diet could help prevent and treat obesity.