The Trouble with Low Glycemic Diets
Low glycemic diets are very much in vogue these days. Most claim that diets high in carbohydrates lead to high insulin levels which prevents the burning of fat which results in obesity. Insulin is the hormone secreted by the pancreas to help glucose gain entry into our cells where it is turned into energy. Glucose is a simple sugar found in all dietary carbohydrates that is used by our cells as the key source of energy for the body and brain. Insulin stores excess glucose as fat. Too much insulin affects the body’s ability to use calories efficiently thereby causing obesity.
All carbohydrates – fruits, vegetables, grains – are converted to glucose in the body. The glycemic index (GI) categorizes carbohydrates according to the speed at which they raise blood glucose levels in three hours. The Glycemic Index was devised about 20 years ago when researchers looked closer at the dietary recommendations for diabetics; which was to eat more complex carbohydrates (starch) because they took longer to process and digest than simple carbohydrates (sugar). When you eat high-GI foods, you experience high glucose levels after meals, called glucose spikes, which are damaging to our arteries and various blood vessels, and they promote insulin production. Eating low-GI foods means you avoid those spikes and dramatic falls in blood-glucose so you get a much steadier stream of energy. You, therefore, reduce your risk of heart disease and other chronic diseases that are implicated by those blood-glucose fluctuations.
Vegetables generally have a low GI below 50 and refined grains with a lot of sugar have a high GI above 80. GI is measured in a clinically controlled setting where 50-gram portions of food are fed to people who have fasted overnight. The rise in blood sugar is measured every 15 minutes for 3 hours and then plotted on a graph. The area under the curve is measured and indexed against pure glucose at 100. That number is the food’s glycemic index. The higher the rise in blood sugar, the higher the glycemic index of that food.
Low glycemic diets claim that High GI foods are bad for weight control for two reasons. Firstly, glucose spikes stimulate hunger because you are getting that dramatic drop in glucose (energy), 90 minutes to two hours after eating. By eating low GI foods you feel fuller for longer and are, therefore, not as likely to go searching for snacks every two hours. Secondly, insulin is a storage hormone that stockpiles nutrients for later use by the body. A high-GI diet causes a lot of insulin to be produced and when you have too much insulin in your body too much of the time, it makes it easier to store fat and harder to burn it.
What works in a lab doesn’t always translate well to the real world. A 50-gram portion of most root and tuber vegetables (carrots, potatoes, beets and parsnips) has a high GI above 65 and about equal to a 50-gram portion of sugar and white bread. According to the GI, these starchy vegetables would be considered dangerous because they are assumed to produce the greatest insulin. However, who only eats these fiber-rich, vitamin and mineral packed vegetables alone for three hours? Usually they are part of a whole meal with protein and fat, both of which slow digestion. And the health benefits of these vegetables filled with cancer-fighting phytochemicals far out weigh any type of bread, whole wheat or white. We doubt anyone got fat eating roasted carrots, potatoes, beets and parsnips.
In addition, carrots have only 195 calories per pound and a boiled potato has about 450 calories per pound while bread contains around 1250 calories per pound (whole grain or white) and sugar contains 1725 calories per pound. The GI index is biased against lower calorie, nutrient rich foods. Let us demonstrate what we mean.
A 2-ounce carrot has 30 calories, 2 grams of fiber, 7 grams of carbohydrates and naturally occurring vitamin A. A 2-ounce serving of whole wheat bread has 160 calories, 4 grams of fiber, 24 grams of carbohydrates and added B vitamins and iron. It also contributes to inflammation in the body because gluten, the protein in wheat, is not completely digested in our stomach. It doesn’t make nutritional sense that 2 slices of bread with 5 times the calories and 3 times the carbohydrates would be more desirable to eat than a carrot. Bananas are another big no-no of low glycemic diets. A 2-ounce piece of banana has 72 calories, 2 grams of fiber, 19 grams of carbohydrates and significant naturally occurring levels of potassium and vitamin C. A 2-ounce portion of pasta has 200 calories, 2 grams of fiber, 41 grams of carbohydrate and added B vitamins and iron. Even though pasta contains more calories and carbohydrates per serving, it has a lower GI than a banana and is considered a better food choice.
The Glycemic Index just doesn’t make sense nutritionally and it surely will not make you thin or healthy due to its emphasis on whole grains versus fresh fruits and vegetables. We believe the best diet is one based on WHOLE FOODS (fresh vegetables, fruits, nuts, seeds, and lean protein) not wheat.