Why glycemic index doesnt matter

Our team goes beyond the quoted evidence, diving deep into research context and study design to point to where the truth lies, and an appropriate level of confidence in that hypothesis.. And of course, what practical takeaways you can actually get from the research. For our inaugural column, here are two recent studies reported in popular media outlets, about health topics including diet, metabolism and aging.

The glycemic index GI is a measure of how much and how fast a food causes a rise in blood glucose after consumption. Glucose pure sugar has a glycemic index of ; everything else has a lower glycemic index. White or processed carbohydrates, like white bread, white rice, flour and breakfast cereal, are usually high-GI. Darker carbohydrates like whole grains and most fruits are usually low- to medium-GI.

This will surprise many dieters— and hell, even some doctors and dieticians— who have hung their hats on low-GI diets. The study Business Insider cites, led by Dr. Glenn Gaesser of Arizona State University, is actually a systematic review that looked at 27 observational i.

In other words, this finding reflects the sum total of decades of research. The truth is quite a bit more complicated. Out of 27 cohort studies, 12 found no difference between high- and low-GI diets, 8 found low-GI diets to be better, and 7 actually found high-GI diets to be better. Now, observational studies can control for variables that can be measured, by correcting for them during statistical analysis.

It would take experiments to figure that out— but we have those too. As for the experimental evidence, GI does still seem to matter a little bit. One notable exception is that low-GI diets with a dietary GI at least 20 units lower than the comparison diet resulted in greater weight loss in adults with normal glucose tolerance but not in adults with impaired glucose tolerance.

Recall the GI is the amount of food which contains 50 grams of carbohydrates — the difference is this: to get 50 grams of carbs from watermelon to calculate GI , you need to eat almost 2. Apparently somebody might have done this because we know the GI of watermelon is BUT there are only 5 grams of carbs in grams of watermelon. The GL of watermelon is 3. Since insulin is responsible for much of the negative effects of carbohydrates, some consider the insulin index superior to GI and GL in terms of its measurements on how food affects your body and your health.

As previously mentioned, foods with a high GL and high insulin index will inhibit fat loss and promote fat storage.

However, some foods with a low GL also stimulate insulin secretion, but this is expected to favor muscle growth. For example, lean beef causes a greater insulin response than what would be predicted by its carbohydrate content, which is close to nil, and lean beef definitely favors muscle over fat. And while the fat added to baked goods would be expected to reduce the GI, the high overall level of easily digestible carbohydrates still leads to a sizeable insulin secretion.

Fructose, in excess, is thought to directly contribute to insulin resistance, the precursor of type 2 diabetes. Essentially, the insulin index measures insulin secretion, whereas the fructose index would assess how likely a food is to contribute to insulin resistance.

For example, I previously gave the examples watermelon and pumpkin. They have a high GI, but low GL because they contain a fair amount of water. And the results for the same food eaten by various individuals can vary by 25 percent. Your genes. Our genes will play a role in how our blood sugar reacts to different carbs. We all have about 5 pounds of bacteria living in and on us.

The majority is in our gut. In addition to gastro-intestinal health, research is also linking gut bacteria to heart health, obesity, risk of diabetes, metabolic syndrome, osteoporosis, mental health, allergies. A study done by Dr. This was a fascinating study and worth reading.

They were able to predict how the body would respond to various carbs by looking at the type of gut microbiome the person had. Listen to the podcast on the Quantified Body. Bottom line The glycemic index and glycemic load can be used as tools to guide you on the effect of various carbs on blood sugar. Eran Segal. Learn More.

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However, you might be able to achieve the same health benefits by eating a healthy diet, maintaining a healthy weight and getting enough exercise. Check with your doctor or health care provider before starting any weight-loss diet, especially if you have any health conditions, including diabetes. The GI principle was first developed as a strategy for guiding food choices for people with diabetes.

The database contains the results of studies conducted there and at other research facilities around the world. A basic overview of carbohydrates, blood sugar and GI values is helpful for understanding glycemic index diets.

Carbohydrates, or carbs, are a type of nutrient in foods. The three basic forms are sugars, starches and fiber. When you eat or drink something with carbs, your body breaks down the sugars and starches into a type of sugar called glucose, the main source of energy for cells in your body.

Fiber passes through your body undigested. Two main hormones from your pancreas help regulate glucose in your bloodstream. The hormone insulin moves glucose from your blood into your cells.

The hormone glucagon helps release glucose stored in your liver when your blood sugar blood glucose level is low. This process helps keep your body fueled and ensures a natural balance in blood glucose. Different types of carbohydrate foods have properties that affect how quickly your body digests them and how quickly glucose enters your bloodstream. There are various research methods for assigning a GI value to food. In general, the number is based on how much a food item raises blood glucose levels compared with how much pure glucose raises blood glucose.

GI values are generally divided into three categories:. Comparing these values, therefore, can help guide healthier food choices. For example, an English muffin made with white wheat flour has a GI value of A whole-wheat English muffin has a GI value of One limitation of GI values is that they don't reflect the likely quantity you would eat of a particular food. For example, watermelon has a GI value of 80, which would put it in the category of food to avoid.

But watermelon has relatively few digestible carbohydrates in a typical serving. In other words, you have to eat a lot of watermelon to significantly raise your blood glucose level. To address this problem, researchers have developed the idea of glycemic load GL , a numerical value that indicates the change in blood glucose levels when you eat a typical serving of the food.

For example, a 4. For comparison, a 2. The values are generally grouped in the following manner:. A GI value tells us nothing about other nutritional information. For example, whole milk has a GI value of 31 and a GL value of 4 for a 1-cup milliliter serving. But because of its high fat content, whole milk is not the best choice for weight loss or weight control.

The published GI database is not an exhaustive list of foods, but a list of those foods that have been studied.