The high glycemic index (GI) diet consists of foods that rapidly raise blood glucose levels. High GI foods have a score of 70 or more on the glycemic scale of zero to 100. Research shows that following a high glycemic diet increases the risk for cardiovascular disease and diabetes. However, research also indicates that high GI foods are beneficial after exercise. Besides post-workout, limit high GI foods at other times. Instead, choose low glycemic foods because they have positive effects on overall health.
Cardiovascular Disease
Researchers investigated whether high GI was linked to an increased risk for cardiovascular disease (CVD). In a study published in the Journal of the American College of Cardiology, researchers did a study of 15,714 Dutch women ages 49 to 70 without diabetes or CVD. During the nine years of follow-up, 556 cases of coronary heart disease were documented. Scientists found that subjects following a high GI index increased their risk of CVD. In addition, the risk was greater for subjects who were overweight.
Diabetes
Although not proven through research, scientists theorized that a high GI diet increased the risk of non-insulin-dependent diabetes mellitus (type 2). Researchers studied 42,759 men without type 2 or CVD. During the six years of follow-up, 523 cases of type 2 diabetes occurred. According to Diabetes Care, scientists found that following a high glycemic diet was associated with an increased risk for type 2 diabetes.
High GI and Exercise
A study published in the International Journal of Sports Medicine had subjects ingest a small portion of the following before exercising to exhaustion: lentils (low GI), potato (high GI), and glucose and water. The results showed that ingestion of the high-GI potato led to a greater increase in insulin than the other meals. Also, subjects were able to exercise 20 minutes longer after eating the low GI food compared with the high GI food.
After Exercise
One of the few times that high GI carbs are beneficial is after workouts. A study published in the Journal of Applied Physiology had subjects exercise to deplete muscle glycogen (stored carbs in the body) on two occasions, one week apart. For the first exercise period, subjects consumed mainly high GI foods for 24 hours after exercise. For the second period, subjects ingested low GI foods for 24 hours after training. Scientists found that high GI foods quickly replenished muscle glycogen for 24 hours post-workout compared with the low GI foods. Quickly restoring muscle glycogen allows for better recovery and stores carbs for the next workout.
Recommendation
Low glycemic carbs appear to be better overall. According to Glycemic Index website, consuming low GI foods provides numerous benefits, including weight control, decreased insulin resistance, diabetes management and improved lipid profile.
References
- Journal of the American College of Cardiology: Glycemic Index Study on Middle-Age Women
- Diabetes Care: Dietary fiber, glycemic load and risk of type 2 diabetes in men
- International Journal of Sports Medicine: Carbohydrate loading before exercise
- Journal of Applied Physiology: Muscle glycogen storage
- Glycemic Index: About Us
