Harnessing the power of the food insulin index
You’ve probably heard of insulin, the vitally important but often misunderstood hormone.
Insulin helps to regulate the production of ketones from fat in the liver. If you want to increase the ketones in your blood, you need to reduce the components in your diet that require insulin. The Food Insulin Index testing helps us to understand which foods trigger the most insulin. 
The chart below shows the results of the insulin index testing (from An Insulin Index of Foods: the insulin demand generated by 1000 kJ portions of common foods, Holt et al., 1997).
Jelly beans are the most insulinogenic, while foods like eggs, butter, bacon and olive oil require less insulin (over the three hours of that insulin was measured).
Bonus: No time to read now? Get this post in PDF to save, reference, email to friends. Click here to get it free.
Which foods raise insulin the most?
As you might expect carbohydrate foods tend to raise insulin the most. However, foods with more protein (e.g. fish, steak and cheese shown to the far left of the chart below) also raise insulin significantly.
Accounting for fat, fibre and fructose
Our recent refinement of the food insulin index data has also identified that:
- both fibre and fructose require less insulin than starch and sugar, and
- fat requires some insulin during the first three hours after a meal (note: the glycerol backbone in fat can be converted to glucose if the body doesn’t have any other glucose coming in).
The chart below shows that we get an even better prediction of the insulin response to the food we eat once we also consider the insulinogenic effects of fat, fructose and fibre (i.e. the R2 correlation coefficient increased significantly from 0.49 to 0.6).
This refined understanding of our insulin response to food is powerful and enables us to:
- rank foods based on their % insulinogenic calories (i.e. foods that are more or less ketogenic),
- quantify the insulin load of your diet (to help you stabilise your blood sugars and/or achieve ketosis), and
- more accurately calculate insulin dosing for people managing diabetes.
Does protein increase insulin?
Foods with more protein tend to require less insulin because they contain less carbohydrates. However, high protein foods like fish, tuna, prawns and steak still elicit a significant insulin response (as shown to the right in the chart below).
Part of the reason that high protein foods require insulin is that most of the amino acids (other than lysine and leucine which are essential and strictly ketogenic) can be converted to glucose (via gluconeogenesis) if there is not a lot of carbohydrates available in your diet. The table below shows the amino acids that are ketogenic vs glucogenic. The ones in the middle can go either way depending on the requirement.
While there is some concern about gluconeogenesis, keep in mind that it is an energy-intensive process. The body would much rather get its energy from fat or carbs than protein.
We lose about 25% of the energy from protein in the conversion to ATP to be used in our cells. By comparison, we only lose about 8% of the energy from carbohydrates and 3% of the energy from fat.  
What does insulin actually do?
While we often think of insulin as an anabolic hormone (to build things up), it can be much more helpful to think of insulin as anti-catabolic (to stop your body from breaking down and falling apart). 
The body uses insulin as a brake to control the flow of energy from storage (via the liver) when there is plenty of food coming in from our diet.
When there is less energy available food, glucagon stimulates the release of stored energy and balances the effects of insulin.
When you consume excess protein beyond what you need for essential bodily functions (muscle and program repose, neurotransmitters etc.), your pancreas will raise insulin to shut off the release of stored fuel from your body while we use up the food coming in from our diet.
Although fat doesn’t require as much insulin hold in storage, all foods require some insulin over the longer term (keep in mind that the food insulin index testing was only over three hours, so it may underestimate the full insulin release from fat and protein).
The bottom line of all this is that if you want to see your abs, manage your blood sugars, lower your insulin levels or reduce your chance of getting one of the modern metabolic diseases, you need to find a way to stack up less fuel (i.e. alcohol, protein, carbs and fat) in front of your body fat.
Does protein raise blood sugar?
As shown in the chart below, consuming a higher percentage of protein will tend to lower your blood glucose.
When you eat protein, you release both glucagon and insulin. In most people, insulin and glucagon are balanced, so your blood sugars remain stable after a high protein meal.
If you are insulin resistant, this signal becomes imbalanced and leads to a more dominant glucogen response from the liver and some elevation of blood sugars. If you are injecting insulin, you may need to top up with some extra so you can metabolise the protein to repair your muscles while also keeping your blood sugars stable.
It is a challenge for most people to overeat high protein foods because they are so satiating. Increasing the protein content of your diet will likely have a net lowering of your insulin and blood sugars. Increasing your % protein intake tends to lower your overall energy intake and hence reduce your body fat levels. This, in turn, lower your basal insulin levels because you have less body fat to try to keep in storage.
A nutrient dense diet tends to contain plenty of protein. Unless you require a therapeutic ketogenic diet (for the management of Alzheimer’s, dementia, Parkinsons or epilepsy), there is no need for most people to worry about “too much protein”.
For people with a functioning pancreas (i.e. you are not injecting insulin), focusing on reducing carbohydrates should be adequate to stabilise blood sugar levels. 
Insulin response to fat
Higher fat foods tend to cause a smaller insulin response. However, there is still some insulin response, even over the first three hours.
Fat is the last macronutrient to be burned (after alcohol, ketones, excess protein and carbohydrate). Fat is easily converted to energy or stored, so only a small amount of insulin is required to store the fat not burned on your body.
Some people believe that they can lower the insulin load of their diet to lose weight, a bit like someone with uncontrolled type 1 diabetes. The photo below shows the same child who has type 1 before and after starting insulin therapy.
However, the reality is that insulin is not only released in response to the food we eat (bolus insulin), but basal insulin is also required to keep the energy stored in our fat and muscles from leaching into the bloodstream.
If you are making your own insulin, your pancreas will not produce any more insulin than is required to hold your fat in storage while you use up the energy coming in from your mouth.
The more body fat you have, the more insulin will be required to keep our body fat locked away in storage. This is why many people who are obese also have high fasting insulin levels. It is not that insulin is causing them to be fat but rather that the high levels of insulin are working overtime to hold their fat in storage. 
If your goal is fat loss, then you need to find a way of eating that allows you to be satisfied with less energy (see Systematising satiety: How to optimise your diet to manage hunger for some practical ideas and the Never Hungry Diet app to check the satiety score of your favourite foods).
The good news is, your fasting insulin levels will come down as your body fat levels decrease.
The ultimate keto calculator
“Is it keto?” is a question frequently asked by keto newbs and a common source of confusion on keto forums and Facebook groups.
So, to answer the question definitively, we created the free “Is it Keto?” web app that you can use to check if a particular food or meal is ketogenic.
The tool is designed to help people who:
- require a therapeutic ketogenic diet (i.e. for the management of Alzheimer’s, dementia, epilepsy, Parkinson’s etc.),
- are managing diabetes and want to stabilise their blood sugars,
- are chasing nutritional ketosis (for a performance or cognitive boost), or
- people who just want a nutritious lower carb diet.
[You can easily set up “Is it keto?” to run from the home screen of your phone like an app for easy reference. For instructions on how to add a webpage to your smartphone home screen click here for Apple and here for Android.]
The Is it Keto? app will tell you if a food or meal is suitable for different goals based on its percentage of insulinogenic calories (see below for details) for that food or meal:
- therapeutic ketosis – less than 15% insulinogenic calories
- nutritional ketosis – less than 25% insulinogenic calories
- low carb – less than 40% insulinogenic calories
- not keto – greater than 40% insulinogenic.
Benefits of the keto calculator
Many people with Alzheimer’s, epilepsy, dementia or Parkinson’s do well on a therapeutic ketogenic diet.
Ketones can supply much-needed fuel to the brain when glucose can no longer be used effectively due to insulin resistance that can develop after years of a poor diet.
Titrating down the insulin load of your diet to low levels can help to provide fuel to the brain for people who have become insulin resistant.
Understanding how much insulin is required for different foods is essential for people who are injecting insulin or taking diabetes medications (i.e. people with Type 1 or Type 2 diabetes). It is impossible to match injected insulin with food perfectly.
The larger the dose of exogenous insulin, the larger the errors you make due to a wide range of factors such as insulin absorption, inaccurate food labelling and measurement.
A highly insulinogenic diet will leave you on a blood sugar roller coaster all day and feeling hangry. It can also leave you feeling very fatigued and wreak havoc on your moods/emotions, among other side effects that make it hard to function in everyday life.
Foods that require less insulin help stabilise blood sugars. Less variation in blood sugars allows better control and lower blood sugars overall. Dr Richard Bernstein calls this “The Law of Small Numbers”.
People injecting insulin will benefit from considering the insulin required for protein when calculating their insulin dose.
Improved blood sugar control can be achieved by titrating down the insulin load of your diet. Many people find that they can reduce or eliminate their diabetes medications once they lower the insulin demand of their food to the point that their pancreas can keep up.
Many people think that ketosis is synonymous with fat burning and hence weight loss, but it not quite that simple.
Our modern food environment is set up to encourage us to buy and eat more food. Meanwhile, whole foods are mainly carbs or fat+protein depending on the season and latitude.
Given the opportunity, we gravitate towards foods that are a mix of fat and carbs that enable us to fill up our glucose and fat stores at the same time and, in turn, leads us to consume a lot more energy and gives us a massive dopamine hit that drives us to keep eating these foods.
Removing processed carbs from your diet and not fearing fat will often lead to improved appetite control, at least compared to a diet heavy in processed foods.
The chart below shows satiety versus carbohydrates, indicating that it’s the foods that are a mix of fat and carbs in the middle that tend to be the easiest to overeat, while less processed foods that are lower or higher carb tend to be harder to overconsume (see Systematising Satiety more details).
There seems to be a “sweet spot” when we consume less than about 30% carbs. However, very low carb diets can involve high levels of added refined fat which can have an adverse effect on satiety.
Unfortunately, some people end up fatter and more insulin resistant after pursuing high blood ketone levels with lots of added fat and ketogenic foods. “Fat to satiety” doesn’t seem to work when we consume refined fat with minimal protein.
If your goal is fat loss, then there is no need to go out of your way to consume high-fat foods. You will produce plenty of ketones as you burn your stored body fat!
The vast majority of the benefits of a ketogenic diet occur when ketones are coming from burning your body fat (endogenous ketosis) rather than from your dietary fat (exogenous ketosis).
Once you have stabilised your blood glucose levels with a reduced carbohydrate intake, the next step on the weight loss journey is to focus on foods that maximise satiety (i.e. less starch+fat and more protein+fibre).
The chart below shows a plot of the satiety score vs insulin load. While high-fat ketogenic foods are more satiating than highly processed junk food, if your goal is fat loss you will benefit from progressing to more satiating whole foods towards the right on this chart.
We don’t really know how much insulin we need in the long-term
One of the most significant limitations of the insulin index is that it only considers the short term insulin and blood sugar response to food (over the first three hours after eating).
The reality is that a large meal can digest for much longer than this. So it is likely that the Food Insulin Index data does not fully account for the long-term effect of protein and fat.
While carbs raise insulin more in the short term, we don’t have any long-term data to help us understand how much insulin each of the macronutrients requires over the long run.
Reducing carbs and moving away from a highly processed diet will improve satiety and reduce hunger. However, in time, you may also need to focus on reducing dietary fat to enhance satiety even more. A high satiety diet will produce plenty of ketones as you burn your body fat.
A high satiety diet also tends to be nutrient dense diet, meaning you will be able to get the nutrients you need with fewer calories which will, in turn, lead to lower levels of body fat and insulin.
Don’t worry if your blood ketones decrease as you approach your goal weight. Metabolically healthy people tend to have lower levels of energy floating around in their blood (i.e. blood sugar, blood ketones and free fatty acids) as well as lower body fat levels.
A ketogenic diet with an emphasis on dietary fat can limit the amount of vitamins and minerals per calorie (aka nutrient density) in your food.
If you require a therapeutic ketogenic diet, you should also make sure your food contains enough of the harder-to-find nutrients.
The chart below shows that a highly ketogenic diet will also contain lower levels of vitamin D, vitamin A, choline, folate, potassium, calcium and omega 3.
By contrast, the chart below shows the micronutrient contained in the most nutrient dense selection of foods.
Nutritious keto foods tailored to your goals
To help you out all this theory into practice, we have assembled a range of nutrient dense food lists tailored to different goals. The right-hand column shows the nutrient profile of each food list. Click on the ‘food list’ links below to get a free printable pdf food list delivered to your inbox.
|the most ketogenic foods|
|optimal foods for therapeutic ketosis|
|well formulated ketogenic diet|
|nutritious low carb foods|
|fat loss & blood sugar management|
|aggressive fat loss|
|the least ketogenic|
Keto macro calculator
If you are tracking your food and want to know what your target macros are, then we recommend running the Nutrient Optimiser Free Report to get your personalised carbohydrate, fat and protein targets.