Do Calories Matter on Ketosis? Thermodynamics vs Insulin

A quick google search of ketosis may leave you thinking that carbohydrates the only reason you are overweight, and that if you are in ketosis that calories don’t matter. But what does the science actually say? Let’s dive in!

Today we are going to be discussing something at the heart of the obesity epidemic. There are 2 schools of thought when it comes to weight gain. One is simple thermodynamics. Calories In Calories Out. If you take in more calories then you expend then you will gain weight. If you take in fewer calories then you expend, you will lose weight. This has been the standard model for obesity for decades.

Recently this model has been called into question, and a more sinister explanation has been put forward. This is the Carbohydrate-Insulin model of obesity. This model has been put into the spotlight by authors like Gary Taubes writing best-selling books on the topic, and by the multiple ketogenic proponents out there.

The carbohydrate-insulin model goes as follows. You eat carbohydrates and so your body secretes insulin. This insulin opens up your fat cells and makes the calories you ingest turn into fat. Because the calories went into your fat cells and were not used to create energy this increases your hunger levels thereby promoting weight gain and eventually obesity.

The only problem is that when you do really well-controlled studies where the food that the participants eat is carefully monitored and patients are not simply writing down what foods they eat the results just do not back up this theory.

If you take 2 individuals and have them live in a metabolic ward where all calories are carefully measured out, and participants are not allowed to eat any extra snacks or skip meals. One individual eats a high carbohydrate diet and the other eats a high-fat diet of the same number of calories both participants will either gain or lose the same exact amount of weight depending on the total daily calories.

Now trust me, I understand how attractive this model can be. I myself believed it 100% even as recent as 3-4 years ago. I can remember having arguments with my fiancé who is a registered clinical dietitian about how fat doesn’t make you fat and carbs are what make you fat. But luckily I continued to do research and kept an open mind and realized that this idea has more to do with dogma than actual science.

So do calories matter?

Yes, they 100% matter. Your total daily calorie intake will dictate whether you gain or lose weight.

Now that being said it can be very easy to overeat simple carbohydrates especially when they are combined with fat and salt. Think Pringles. You know the phrase “Once You Pop You Can’t Stop.” This is really true. Processed foods such as these hijack your body’s natural feeding mechanisms and trick you to consuming more than you would if you were eating a single macronutrient whether that be carbohydrate, fat, or protein.

So different types of foods can have an effect on how much you eat which would either increase or decrease your total calories.

I hope that this has been helpful. Make sure you are subscribing and following so you don’t miss out on any more great content. Again this is Floyd Meyer reminding you to Eat Better so you can Do More!




Hall, K. D. (2017). A review of the carbohydrate–insulin model of obesity. European Journal of Clinical Nutrition, 71(5), 679–679. doi: 10.1038/ejcn.2017.21

Kirkpatrick, C.f., et al. “Review of Current Evidence and Clinical Recommendations on the Effects of Low-Carbohydrate and Very-Low-Carbohydrate (Including Ketogenic) Diets for the Management of Body Weight and Other Cardiometabolic Risk Factors: A Scientific Statement from the National Lipid Association Nutrition and Lifestyle Task Force.” Journal of Clinical Lipidology, 2019, doi:10.1016/j.jacl.2019.08.003.


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