Carbs With High Glycemic Index Do Not Cause Obesity

There are several popular diet books that have hit the bookshelves recently that claim that diets with too many carbohydrates will lead to high insulin levels. This in turn will make it harder to burn fat and lead to obesity. These books have been pushed on most of the TV networks and on the Internet. The authors have been on Oprah. Many of the books get listed as #1 on the New York Times Bestseller List, but what they claim about high glycemic index foods is very questionable. They profess that high glycemic index foods such as parsnips, potatoes and carrots are the most dangerous because they seem to produce the largest insulin response. But a study of the Pima Indians in Northern Mexico proves their theory is wrong.

The Pima Indians are an interesting test case as there are large communities living in Mexico and Arizona. The Mexican Pima Indians have a predominantly Mexican cuisine whereas the Arizona  Pima Indians have adopted many western appetites and ideas to food.

On average, it was found that the Pima Indians in Mexico weigh 60-65 pounds less then the Pima Indians who live in Arizona. This is interesting because the Pimas of Mexico eat high glycemic index foods consisting mainly of corn tortillas and potatoes.

The Pimas of Arizona eat a Westernized diet with more protein and fat in their diet. Diabetes is very prevalent in the Arizona Pimas by age 50, whereas the Mexican Pimas are very rarely afflicted. So, if a high glycemic index food diet raises insulin levels and promotes weight gain, then why aren’t the Mexican Pimas becoming obese and developing diabetes?

One theory is that the Mexican Pimas are much more active then the Arizona Pimas. One daily exercise routine will improve the insulin resistance for one day or more. Exercise depletes the glycogen in the liver and muscle so these tissues will quickly take up blood sugar after an exercise in order to replenish their glycogen storage area. When people are inactive the muscle glycogen storage area is full and they resist the action of insulin. They no longer have any use for the blood sugar when their glycogen stores are completely full and they are not moving.

A genetic difference in the two groups is not an answer either, since both Pima groups come from the same genetic stock. It is generally the consumption of excess calories in any form and inactivity that will lead to excessive obesity. So, the theory that high glycemic index food is a leading cause of diabetes and obesity is just not true completely accurate and has been falsified by the Pima Indians. Thus it is more accurate to conclude that obesity leads to insulin resistance and high insulin levels.

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