For decades now, I have believed that polyunsaturated fat from sources such as corn oil, soybean oil, safflower oil, and canola oil is a very bad idea. They are highly prone to oxidation and associated with all kinds of diseases. But the more I researched, I was coming to the inevitable conclusion that monounsaturated fat could also contribute to obesity.  That was the beginning of the croissant diet.

Monounsaturated fat has always been a kind of happy middle ground for traditional nutritionists who have moved away from promoting soybean oil and Weston A. Price people who promote butter. No one ever really has anything bad to say about olive oil. But everything I learned suggested that olive oil could cause weight gain.

How the Diet Works

Here is my nutshell version of how this works (once again, a shout out to Hyperlipid for figuring this out, I didn’t): The primary mechanism by which the body stops the flow of energy into fat cells is the production of free radicals, aka Reactive Oxygen Species (ROS), at the conserved molecular bottleneck in the electron transport chain of the mitochondrial inner membrane. The ROS block the activity of several proteins involved in insulin signaling, leading the fat cells to become physiologically and reversibly insulin resistant. The job of Insulin is to send a signal to tell fat cells to store energy. If the fat cells are (temporarily) insulin resistant, they won’t take in any more energy. Fat loss will occur. Long-chain saturated fats create lots of ROS. Unsaturated fats don’t.

All of this suggests that obesity isn’t about carbohydrates per se, it’s about insulin signaling. Carbohydrate consumption causes insulin release and so keto diets presumably work by minimizing the release of insulin. But protein consumption ALSO causes insulin to be released. Fat consumption, especially saturated fat, enhances the insulin response to carbs and protein. So, you can manage to release a lot of insulin on keto. In the mice fed the high stearic acid diet, the saturated fat was producing ROS in the mitochondria, which directly shut down insulin signaling, and they lost abdominal fat. All of which is to say that maybe a diet of croissants is a more direct way of shutting down insulin than a keto diet?

Why I Worried It Wouldn’t Work

I had three primary concerns that changing the ratio of my dietary fat wouldn’t work or would work very slowly.

What if my fat stores were already loaded with polyunsaturated fats and that my body would blend my body fat and my dietary fat into a mixture that wouldn’t produce enough ROS to generate insulin resistance in my fat cells? My understanding is that when you consume fat it is transported as a triglyceride (3 fats hooked together) from your intestine to your fat cells in a chylomicron. Only once the fats are absorbed into the fat cell lipases in the fat cells convert the triglycerides into free fatty acids which are then used by the fat cell for fuel or released into the bloodstream for other cells to use as fuel. Do fat cells have some type of LIFO (last in, first out) mechanism for using fat, so that dietary fat is prioritized over stored fat?

I still don’t know the answer to this question.

My second concern was that if I’ve largely, although certainly not entirely, been avoiding high sources of PUFA all these years, was the thing that was causing me to be fat my own overproduction of the SCD1 protein? SCD1 is a gene that converts saturated fat into monounsaturated fat. If I were making a lot of it, maybe my fat cells would sabotage me by converting all the precious dietary saturated fats into unsaturated fats before sending them to the mitochondria.

My final concern was that maybe I was wrong and weight loss is all about carbs and by eating croissants I’d eat too many carbs, produce too much insulin and I wouldn’t lose weight, or I’d gain weight.

I was planning on using myself as a guinea pig, but I had my concerns and I wanted to stack the deck in my favor. I ordered some stearic acid so I could feed myself just how the mice were fed.

Enter the Croissants

Let’s take a brief aside to talk about WHY croissants. As I’ve already stated, I haven’t been much of a white flour fan for a very long time now. But I also put a lot of faith in French food traditions, and the French eat a lot of white flour. Also, I know that white flour is very good at absorbing fat and saturated fat is the thing that makes this whole diet work. Lastly, white flour is a nutrient-poor food, but croissants are great at holding nutrient-dense foods like liverwurst! I won’t eat sautéed liver, but I’ll eat a liverwurst croissant sandwich.

More importantly, I was trying to prove my point that “A primary regulator of whole-body energy balance is the ratio of saturated to unsaturated fat.” If I was going to make myself into a guinea pig, I didn’t want anyone to accuse me of creating a diet that worked because of some other mechanism. Such as that it was secretly a keto diet or that it was a gluten-free diet or a grain-free diet or a low food reward diet etc. Nope, I wanted to demonstrate that I, a person who had managed to approach morbid obesity, could lose weight by eating tasty croissant sandwiches.

Also, yes, it’s a hilarious stunt. Fine, I admitted it, are you happy now?

Fast forward two weeks from the day I began the carnivore diet, and I’m in my kitchen with a five-pound bag of stearic acid, a pound of butter, a bag of flour, and an image of a recipe my friend sent me out of the Culinary Institute of America cookbook for making “laminated dough,” the secret to making croissants. Of course, I had made croissants twenty years earlier at the French Culinary Institute. It was time to revisit my roots.

Stearic acid is a strange ingredient to cook with. It has a melting point of over 150 degrees Fahrenheit, which means that at room temperature it has a texture like candle wax. If you sauté something in stearic acid and put it in your mouth while the stearic acid is still molten, it will immediately turn to wax in your mouth. It comes in a beaded form, like little grains of rice.

I didn’t really know how to proceed with this, so I just mixed a bunch of stearic acid granules into the flour to substitute for one-third of the butter and made the croissant recipe. The result was… dense. The stearic acid absorbed into the flour but not in an appealing way. It was kind of like a wax impregnated croissant. If you toasted the croissants, the result was edible. I started making pizza croissants. I would cut the croissant in half, toast it, then layer it with marinara, mozzarella, and pepperoni.

My plan was to completely stop drinking when I went on the croissant diet.

Except that the stearic acid came on a Wednesday, and I was excited to try it so I made croissants Thursday night – specifically this was Thursday, August 8th, 2019 – and I had fun weekend plans so I ate croissants all weekend and continued to drink red wine. I was going to legit start the diet on Monday, meaning no more red wine. But the scale dropped by about five pounds between Thursday morning and Sunday morning. Wow! So, I figured if it ain’t broke don’t fix it and I continued to drink red wine and eat croissants. And that was how things went for two weeks.

This is Part Two of a six-part series. Find Part One here.

Brad Marshall

Brad Marshall is the author of the Blog Fire In A Bottle, the author of The SCD1 Theory of Obesity and the creator of The Croissant Diet.  Mildly obsessed with food and its history, his work focuses on trying to place current ideas about diet, including keto and carnivore diets into the framework of traditional Dietary patterns.  For instance, the French diet before 1970 combined flour, sugar, butter and wine and the population was lean. Brad Marshall is the author of the Blog Fire In A Bottle, the author of The SCD1 Theory of Obesity and the creator of The Croissant Diet.  Mildly obsessed with food and its history, his work focuses on trying to place current ideas about diet, including keto and carnivore diets into the framework of traditional Dietary patterns.  For instance, the French diet before 1970 combined flour, sugar, butter and wine and the population was lean. Brad wrote The ROS Theory of Obesity which posits that ROS generation in the mitochondria of fat cells could provide the mechanism that explains why a traditional chinese peasant diet - low fat with 85% of calories from starch; a French diet combining butter, wine and flour and a modern keto diet could all be expected to produce leanness but combining flour with polyunsaturated fats is a recipe for obesity.  The core idea comes from the Protons thread of Peter Dobromylskyj’s blog Hyperlipid.  Brad tested this hypothesis with his dietary experiment The Croissant Diet.  The SCD1 Theory of Obesity is the second part of the theory.  It deals with the composition of stored body fat, which gets blended with dietary fat before being burned in the mitochondria

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