A New Model To Explain Weight Gain?

The common advice given to solve the overweight, obesity, and metabolic health problems much of the world is suffering from has been to “eat less, and move more”. This advice is derived from what is called the energy balance model (EBM) of metabolism. This model is based around the theory that weight gain and loss are dictated by the relationship between the calories you consume and the calories you expend.

The equation is very simple, eat more calories than you burn and you will gain weight. Burn more calories than you eat and you will lose weight. Hence when someone has weight to lose, if you eat less (consume less calories) and move more (burn more calories) you should lose weight.

Despite this simple, straightforward solution for weight loss, it does not appear to work very well.

The average person goes to their doctor for their once a year check up and year after year the scale goes up. One study showed that men will gain 3.4% and women 5.2% over the course of 10 years. Some people in this study actually gained more. 6.5% of the women in the study gained 25% or more of their initial body weight over the course of 10 years[1].

Lets put this in perspective. I weigh 150 lbs, a 3.4% weight gain would put me at 155.1 lbs.

That’s not bad right?

No, not terrible, but context is important. I am starting at a very healthy weight for someone who is approximately 70 inches (5ft 10in) tall. We also need to take into account my body composition. I am roughly 10% body fat, that means I have about 15lbs of body fat on me, the rest is lean mass (muscle, bone, water, etc). So if I added 5lbs of pure fat on my body it’s not a huge deal.

The average body fat for someone my age is 20%, if that was me I would have 30lbs of fat on me [2]. Adding 5lbs more would not be so good. Worse still is that this compounds each decade meaning this decade I would add 5lbs but the next decade it would be more, and so one and so on.

And this is why we see rising rates of obesity and metabolic health issues in western societies…


Back to our fictional example…

If I am the average guy my age and my doctor sees this rising trend in my weight and maybe also signs of poor metabolic health like high fasting glucose and elevated triglycerides, he will give me the advice “Ryan you need to eat less and move more. Come back in a year and we will see how you are doing.”

This advice seems simple enough. Most people walk out of the office not thinking much of it until it comes time to make the change.

Maybe they start reducing how much they are eating. Less chips, less cookies, less soda, and unfortunately less animal protein (because they heard that’s bad for you as well). Maybe they even skip trying to skip a meal because that’s a sure fire way to eat less.

Where does this leave them?


They continue to white knuckle it until finally they give in, hitting the first drive through they see followed by a whole pint of Ben and Jerrys. Now they feel bad about themselves and give up on this whole eating less thing.

What about the move more part of, advice? What exactly does that mean?

Most people end up doing whatever “fad” exercise that is popular at the moment, which most likely is 6 days a week of some kind of extreme high intensity exercise. Initially it might feel good, but after a few weeks, they are sore, tired, and completely burn out because it was too much too fast. Not to mention all this extra intense moving makes them MORE hungry!

Again, their will power wanes and they are back to “Netflix and chill”.

Telling people to move more and eat less certainly seems like it’s not working, so could the whole energy balance model be wrong? Could there be something else going on that might be the cause of the excessive weight gain and metabolic health problems we are seeing today?

Enter the carbohydrate-insulin model (CIM).

The CIM says that hormonal issues driven by eating high glycemic load foods cause an excess energy balance in the body and lead to fat gain.

To understand CIM better we need to understand what glycemic load is.

You may have heard of a similar metric called the glycemic index. The glycemic index describes the potential of a food to raise your blood sugar. However there is a problem with the glycemic index. Here is a good example.

The glycemic index of watermelon and a donut are the same. Does that mean eating watermelon is just as bad as a donut? No! Just because watermelon and a donut have the same potential to raise your blood sugar, you would have to eat an unrealistic amount of watermelon to do so. This is because a serving of watermelon only has 11g of carbohydrates while one donut has 23g (on average).

This is where glycemic load comes in. Glycemic load is calculated by multiplying the glycemic index by the number of grams of carbohydrates in a serving of the food and then dividing that by 100.

GLFood = (GIFood x amount (g) of available carbohydrateFood per serving)/100

If we go back to our watermelon and donut example, the glycemic load of watermelon is 8.36 while the glycemic load of a donut is 17.4. For a typical serving of a food, glycemic load would be considered high with a glycemic load greater than or equal to 20, intermediate with a glycemic load of 11-19, and low with a glycemic load of less than or equal to10.

Now that we have a better understanding of what glycemic load is, let’s see the role it plays in weight gain according to the CIM.

The CIM asserts that high glycemic load foods will raise your blood sugar causing the body to release a hormone called insulin to take the sugar in your blood and store it in your muscle, liver, and turn it into fat in your body. However, since the glycemic load is so high insulin remains elevated for an extended period of time after eating, preventing the body from accessing its stored energy (fat) in the hours after the meal. The body needs energy to keep functioning so it starts to send signals to your brain to cause you to eat again so it can get more fuel. You reach for more high glycemic load foods and the vicious cycle continues causing you to overeat and gain fat.

As you can probably guess, the CIM dictates that in order to solve the obesity epidemic and stop people from increasing their body fat they eat a low-carbohydrate diet. By removing most of the carbohydrates from the diet there will be no need for excess insulin to be released allowing the body to utilize its stored energy (fat) for fuel when you are not eating. The CIM advocates people eat healthy fats (avocado, olive oil, animal fats), protein, and low glycemic load vegetables and fruits such as above ground vegetables, berries, and legumes. (Sounds a lot like an ancestral diet to me.) Fat and protein have virtually 0 effect on your insulin and above ground veggies, fruits like berries, and legumes would require you to eat a lot of them in order to get a huge carbohydrate load from them.

The key difference between the CIM diet and the EBM is that the CIM focuses on insulin while the EBM focuses on calories. Because nearly all processed foods have a high glycemic load if you follow the CIM it forces you to eliminate most of those foods. However this is not without side effects that can influence weight loss.

Processed foods are not only high in carbohydrates but they are also high in calories and very easy to overeat. If you eliminate processed foods and tell someone to replace them with whole foods as the CIM advocates you are almost certainly not only lowering insulin, you are lowering calories and eating foods that will fill you up more. For example, protein we know is the most satiating macronutrient around. In addition you are limiting food variety which keeps people from being able to override their fullness sensation.

So is it really that the CIM is lowering insulin or is it that you are lowering calories and keeping people from overeating?????

In a gold standard study done on males who were placed in a metabolic ward in a hospital researchers showed that there was no difference in fat loss after 4 weeks on a low carb diet and 4 weeks on a high carb diet while in a 300 calorie deficit on both diets. Since the participants spent the 8 weeks of the study in a metabolic ward all meals were provided and controlled for as was physical activity. The only difference between the two arms of the study was whether participants consumed a high carb or a low carb diet. Calories, protein, physical activity, and caloric deficit were all the same. When on the low carb diet, participants ate 31g of carbohydrates and had measurable levels of ketones indicating that insulin was kept low. When on the high carb diet participants ate 300g of carbohydrates meaning that insulin must have been high in order to store those carbohydrates. If the CIM was right you would predict that while participants are on the high carb diet they would lose less weight than when eating the low carb diet. However that was not the case, it appeared that because each diet maintained a 300 calorie deficit they lost the same amount of weight regardless of the number of carbohydrates they were eating [3].

One of the issues I have with the CIM of obesity is that it seems to discount the role of calories in fat loss and gain. For example, a the most recent paper on CIM [4] states the following:

“A practical strategy is to substitute high-GL foods (refined grains, potato products, concentrated sugars) with high-fat foods (e.g., nuts, seeds, avocado, olive oil), allowing for moderate intake of total carbohydrate from whole-kernel grains, whole fruits, and legumes and nonstarchy vegetables. For those with special susceptibility, such as high insulin secretion or severe insulin resistance, stricter reduction in total carbohydrate may be optimal.”

The problem I have with the above suggestion is the part where they suggest replacing high glycemic load foods with high fat foods. Calories matter! If you go hog wild on the nuts, seeds, avocado, and olive oil you will gain fat! Not to mention there are more and more high fat low carb processed foods coming to the market today that are just as easy to overeat as the high carb foods they are meant to replace. In practice I have seen plenty of people eat extremely low carb diets that still can’t lose fat or even gain fat because they are eating too many calories from nuts, seeds, oils, and low carb “treats”.

Now here is my biggest gripe with the CIM….


Even with all the flaws in the EBM, at least it takes into account physical activity and its role in weight loss and weight maintenance. Even more mind blowing to me is that the CIM is based around insulin being the main cause of fat gain. You know what also keeps insulin low?


When we exercise we burn the glucose from carbohydrates stored in the working muscles. In order to get more fuel into the muscle when it is being worked, the body has developed a way to get glucose into the muscle WITHOUT INSULIN! You heard that right! Glucose from carbohydrates can be moved into your muscles without insulin.

The other reason why the CIM model should be advocating exercise is that when we strength train we add muscle mass. As I mentioned above, muscle mass is one of the best storage sites for carbohydrates. The more muscle you have and the more you work that muscle the more places you have to store carbohydrates without having to turn them into fat. And again, if you are moving those muscles you can put that carbohydrate in the muscle without insulin.

It’s mind blowing to me that the advocates of the CIM completely ignore the role of physical activity on insulin levels.

Here is the real issue for the average person who has been frustrated by the advice from the EBM and has turned to the CIM.

They hear insulin is the enemy, they remove anything that raises insulin in the body, no fruit, no potatoes, no legumes, nevermind never having cakes, cookies, french fries again in their lives. They only eat protein and above ground veggies. They crave something else so they turn to snacking on high fat foods like nuts, seeds, and low carb processed foods and treats. The caloric load from these high fat foods slows any weight loss they might have seen at the start. This gets them frustrated, willpower wains, and they get frustrated and give up. This sounds a lot like the frustrations when following the EBM!

In addition, since there is no mention of physical activity in the CIM and they hear from all the influencers on the internet that exercise is pointless for weight loss, they are not even doing any physical activity!

So what is the answer?

I personally think a good starting point might be to combine both models! Shocker I know…

We want to eat less but also not be hungry. How can we do that?

Eliminate the processed high carb foods as the CIM advocates, and replace them with whole foods. That means protein, vegetables, and fruits, with a moderate amount of high fat foods like nuts, seeds, avocado, olive oil etc (use them as a condiment!). This means instead of having your Subway sandwich, bag of chips, and soda for lunch, have a salad with all the veggies you want, a big heaping portion of your favorite protein (grilled with spices on it), a side of fruit, and your favorite 0 calorie carbonated drink. Throw a reasonable amount of olive oil on your salad with a couple of nuts and seeds for some crunch.

This meal keeps insulin low, is very filling, has a little bit of sweetness with the side of fruit, and provides adequate protein.

Instead of saying “move more” as in the EBM or completely leaving out physical activity as the CIM does, in this model we are going to give some more detailed advice.

Each day you will strive to get 2-3 20 minutes of intentional low level activity. This could be going for a walk, a bike ride, a scooter ride, hike, gardening, moving the grass, playing with your kids/grandkids, whatever you like just keep it easy. Then 2-3 days a week you will strength train for 30 minutes or more. This doesn’t mean you need to go to the gym and use barbells and dumbbells. All it means is that you need to challenge your muscles in some way.

That might mean getting up and out of a chair and lifting some soup cans over your head for some. For others it might be using their own body weight and doing bodyweight squats, push ups and inverted rows on a table. Others might be fine using bands and a suspension trainer. More advanced people might be going to the gym and using the machines, barbells, and dumbbells there.

With the movement piece in place it adds more flexibility in the diet. Now when it’s your birthday and you want to have a burger, fries, and a piece of cake all that movement and muscle can buffer the carbohydrates and calories from that meal and it won’t be so detrimental. You can still have those days where you have some of those foods and avoid the all or nothing approach to your diet.

Even with this model, we are missing key pieces like sleep, stress management, and social connection, all those also play an important role. However the above model takes into account hormones, calories, and movement and provides a sustainable model for long term weight lose. Unsurprisingly, this also reflects an ancestral model to health and better matches what our bodies expect in terms of food intake and physical activity.

In my health coaching practice and all the content I produce I try my best to not take an extreme model to health, wellness, and physical performance. Everything in our body is very nuanced and there is no one way to accomplish your goals whatever they might be. To get more non-dogmatic, nuanced advice to achieve your goals and overcome your obstacles use the form below to sign up for my newsletter using the form below. It is the best way to keep tabs on everything I put out on a weekly basis.

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  1. (n.d.). The 10-year incidence of overweight and major weight gain in US …. Retrieved September 15, 2021, from https://pubmed.ncbi.nlm.nih.gov/2310286/
  2. (2020, October 30). DXA reference values and anthropometric screening for – Nature. Retrieved September 15, 2021, from https://www.nature.com/articles/s41598-020-73631-x
  3. (n.d.). Energy expenditure and body composition changes after an …. Retrieved September 17, 2021, from https://academic.oup.com/ajcn/article/104/2/324/4564649
  4. (n.d.). carbohydrate-insulin model: a physiological perspective on the …. Retrieved September 17, 2021, from https://academic.oup.com/ajcn/advance-article/doi/10.1093/ajcn/nqab270/6369073

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