If you have ever tried to diet, you might be familiar with the concept of low-carbohydrate or ketogenic diets. Depending on how far down the rabbit hole you have gone, you might even have heard of the carbohydrate-insulin model (CIM). This is the mechanism that, in contrast to the conventional energy balance model (EBM), is proposed by low-carb and keto advocates as the true explanation for the obesity crisis in society today. The latest version of the CIM says that eating carbs results in various signals that ultimately lead to increased energy intake and decreased energy expenditure, which, ironically, seems to align with the EBM. The trouble begins when followers of these diets use the CIM in a Motte and Bailey fashion. The model as described in the literature acts as the Motte – uncontroversial and easy to defend. Whereas, what most people see is the information shared on social media – the controversial claims that spark debates and outrage; this is the Bailey. When the Bailey is attacked, defenders retreat to the Motte. Likewise, when the controversial claims are debunked, low-carb advocates retreat to the less controversial version of the CIM. We won’t be delving into the nuances of the CIM or the EBM – that’s a post for another day. We will, however, go through some of the claims you have probably seen on social media.
“Current guidelines don’t work, therefore the EBM must be wrong”
The criticism here is aimed at guidelines and public health initiatives to eat less and exercise more. The fact that the obesity pandemic continues to worsen is used as evidence that the EBM is flawed. What this reasoning fails to consider is the easily accessible, inexpensive, energy-dense, hyperpalatable foods and drinks of increasing portion sizes consumed by people leading increasingly sedentary lives, so it should come as no surprise that most people do not follow these guidelines.
“Carbohydrate intake is the primary cause of obesity, and insulin its primary effector”
There are a few simple rebuttals to this claim. Vegans typically have diets higher in carbohydrate than non-vegans, and yet are, on average, significantly leaner. Similarly, carbohydrate makes up a massive part of the diet for endurance athletes, and they also are very lean. Both type 1 diabetics and some enhanced bodybuilders inject exogenous insulin directly, but don’t become obese. The drug Semaglutide increases the post-prandial insulin response yet has been shown to be very effective for weight loss.
“Sugar is as addictive as heroin”
Respectfully, I’ve never seen someone go into debt or lose their house or ruin relationships to suck on a sugar cube.
“You can eat as much fat as you like, and you won’t gain weight”
While it is true that insulin is a key signaller in nutrient storage into fat cells, and eating fat has effectively no impact on insulin, fat storage can occur without either carbohydrate or insulin. There are various other mechanisms at work that do the same thing. So, over-eating either carbohydrate or fat will lead to excess fat storage and weight gain.
“You can’t lose weight while eating carbs”
We have so many studies now showing this claim to be false. 50 years ago, a study was published showing a very-low-calorie diet made up of 95% carbohydrate from rice and fruit led to huge weight loss. More recently, the DiRECT study has shown weight loss and diabetes remission from a very-low-calorie diet made up of 60% carbohydrate. So, clearly, it is possible to lose weight while eating carbs. But could there be more weight loss from a low-carb or keto diet? No. If we look to Dr Kevin Hall and his massively well-controlled studies comparing low-carb to low-fat (ie. higher carb) diets for weight loss, there is no significant difference. For all intents and purposes, a calorie is a calorie, whether it comes from carbohydrate or fat.
Summary
Okay, but how do low-carb or keto diets work, then? Well, it turns out completely cutting out an entire macronutrient generally leads to an energy deficit. Here’s the bottom line: it doesn’t matter. If you like your keto diet, and it’s working for you, you carry on. But carbs are nice. And also very useful for athletes, but I’ll save that rabbit hole for another post.
If you still don’t believe me that calories are king and that your body definitely doesn’t break the laws of physics, I invite you to work with me. We can track your carbs and calories over a period of time and then manipulate them both to see which one causes you to gain or lose weight.
