You may have heard of the glycemic index – a scale with figures representing the relative ability of a type of food to increase the level of glucose in the blood, more specifically, carbohydrates. A rise in blood glucose usually corresponds to a rise in insulin secreted from the pancreas into the blood to deal with the glucose molecules released into the bloodstream, but the two are not the same. Where the glycemic index typically only measures the effect of sugars from carbohydrates on glucose levels in the blood, the food insulin index measures the effect of carbohydrates, proteins and fats on insulin in the blood.

Where you might get a lean chicken breast having zero effect on blood glucose levels, a large effect on insulin can be seen contrary to what would be expected from a food with a glycemic index of close to zero.

The Food Insulin Index Explained

Whilst the insulin index is similar to the glycemic index and glycemic load of different foods, they measure different factors. The insulin index will tell you how much the concentrations of insulin in the blood are elevated two hours after the food is ingested. A number is typically assigned to each type of food, with 0 showing a food that has zero effect on insulin. Anything about 40 starts to have a rather moderate effect on insulin levels in the blood and anything with an index of over 65 has a significant effect on insulin in the blood.

How blood glucose affects insulin, although high protein foods can also elicit a great insulin response.

Since not only carbohydrates raise insulin, but protein does as well, this index is more useful for diabetics and those who are insulin resistant and can also help to lower the demands for insulin on your pancreas. To some extent, fat also raises insulin levels slightly after a meal but to such a marginal amount that people can stay in ketosis whilst consuming butter, coconut oil or MCT (medium chain triglyceride) oil without raising insulin levels so much to kick them out of ketosis.

For those unaware, ketosis is a state in which the body utilises ketones as the primary source of energy. It does this by oxidising fats (breaking down fats) to turn into ketones to use for energy as an alternative to glucose. Spiked insulin usually shuts off this process since insulin will encourage nutrients to be shuttled into the body’s cells rather than to be broken down for energy, but ketosis is a topic for another day!

Why the Insulin Index Matters

Insulin is an anabolic hormone which helps to build things up in our body. It is used to control the flow of energy storage from the liver when sufficient energy is coming from dietary fuel i.e. our body stops breaking down glycogen and fats and uses the food being consumed.

One way you could look at it is that by raising insulin levels drastically, you are preventing potential fat loss since high insulin levels will turn off the ‘fat burning switch’ in your body by decreasing how much glucagon is secreted; a hormone which stimulates the release of stored energy and balances the effects of insulin. The lower your insulin levels, the more potential you have to burn fat as a source of energy and by extent, the more likely you are to lose weight in the form of body fat.

Ideally, insulin is best kept low as this will help to stabilise blood sugar levels and keep energy stable throughout the day. The body is particularly receptive and able to deal with insulin following bouts of intense exercise in which foods with a high insulin index can be useful to get the macro and micronutrients the body needs to recover from exercise.

Insulin Index for Different Macronutrients

Typically, we want to keep insulin secretion low. If blood sugar is low, insulin secretion will also tend to be low.

  • Carbohydrates in the form of refined, processed foods, fruits, sweets and sugary treats will cause the greatest insulin response.
  • Protein causes the next greatest insulin response with foods like tuna or lean chicken breast eliciting a higher insulin response than chicken wings due to the fact that chicken wing has fat on it which reduces the insulin response.
  • Fat has the least effect on insulin, causing very little dietary response at all if any.

Fat, Fructose and Fibre in the Insulin Index

Fibre and fructose are both carbohydrates although your body doesn’t technically digest fibre. Fibre isn’t actually digested by your body and passes through your colon. However, fibre acts as a prebiotic for the bacteria in your gut, helping to encourage the growth of a diverse gut microbiome.

  • Both fibre and fructose require less insulin than starch and sugar
  • Fat requires some insulin during the first 3 hours after a meal

The Insulin Index Isn’t Just About One Food

Whilst we may have values that tell us how much a certain amount of one type of food spikes insulin in the blood, that is not looking at the insulin index from a realistic perspective. How many of us have just one type of food for a meal?

In fact, the insulin response can actually be diminished by consuming fats with protein at the start of a meal as they elicit a lower insulin response than consuming carbohydrates at the start. When you consume carbohydrates at the end of a meal, the effect they have on insulin is lowered. In addition, by saving carbohydrates for the end of a meal you can help to lower the blood sugar spike that tends to occur by having them!

To get you a better idea of which foods are more insulinogenic than others, here is a graph from Marty Kendal of that demonstrates clearly the effects of different types of foods on insulin levels.

The effects of different foods on insulin

On the x-axis, you can get a rough idea of how protein and fibre affect the food insulin index. The effect of protein on the insulin response is just about half of that of carbohydrates, with fibre helping to reduce the insulinogenic response.

How to use the Food Insulin Index

Use the food insulin index to choose foods which won’t spike your insulin as high since high insulin levels wreak havoc on our bodies. Insulin is necessary for our cells to get the nutrients and energy they need, but most people eat foods that put their insulin levels in a chronically high state (along with chronically high blood sugar). Keeping insulin levels low, will help your cells to be insulin sensitive so that when you do eat foods that trigger an insulin response, they will be receptive to obtaining the nutrients and energy from food.

Chronically high insulin levels will cause cells not to respond to the insulin signals and thus they won’t let glucose and other nutrients into the cell. Keeping insulin levels low, will help your cells to be insulin sensitive so they listen to the signals released by the hormone insulin.

High insulin levels are linked with:

To help avoid the potential risks of high insulin levels, try to be mindful about what foods you eat and their effect on insulin, and if possible save the carbohydrates for last to minimise the insulin spike! If anything, just try to ensure that your insulin levels are not high all the time.

Had you heard of the food insulin index? Let me know down below!