The Super Sexy Metabolism of Macronutrients (1 of 2)

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Jonathan: Hey everyone, Jonathan Bailor here with Carrie Brown back with another Living the Smarter Science of Slim podcast. Carrie, what’s going on?

Carrie: Hello Jonathan.

Jonathan: It is cold in the studio today.

Carrie: Yes it is, and…

Jonathan: And…

Carrie: I was just wondering if I should share our little secret.

Jonathan: I think you should.

Carrie: We’re wearing matching socks.

Jonathan: Matching socks.

Carrie: The studio is freezing and I had extremely cold feet and I wore sandals because I’m a smart girl and Jonathan thank goodness had a spare pair of socks in his bag so we are sitting here podcasting in matching socks. How cute is that?

Jonathan: We know the listeners love to get helpful tips and these socks were actually a gift from my dear father-in-law who purchased them I believe from Costco. You know we love Costco. They’re these kind of wool socks but they’re not itchy and they’re like slipper socks. They’re super, super comfortable so if you have a Costco around your house and you see their little wool-type socks they are delightful so you may want to give them a try.

Carrie: They are fantastic podcasting socks.

Jonathan: They are the official podcasting socks for this podcast. Like the official sponsor of the NFL, these are the official socks of the Smarter Science of Slim podcast.

Carrie: Yay!

Jonathan: Carrie, besides socks what are we talking about today?

Carrie: Well I have a question.

Jonathan: Yes.

Carrie: I want to know what happens to proteins when you eat them and what happens to fats when you eat them and what happens to carbohydrates when you eat them. Go.

Jonathan: Ahhhhhhhhhh! Well just before I dig into the science Carrie, can you talk a little bit about why you want to know those things because maybe it will help folks to…

Carrie: When I first started being introduced to the Smarter Science of Slim it made a huge difference to me when I understood the different way our bodies deal with the different types of nutrients that we ate. I thought that if we shared that very simply with our listeners it would also help them to focus on the ones that are better for us because they understand what happens physiologically within our bodies.

Jonathan: Love it, love it, love it. So this really boils down to the – well one of the calorie myths, most everything boils down to one of the calorie myths but the calorie myth about a calorie is a calorie is a calorie is a calorie. Once we free ourselves from that calorie myth it becomes very clear why the quality of what we consume is so important because a calorie is not a calorie is not a calorie. As Carrie was alluding to, when you get a calorie from fat versus when you get a calorie from carbohydrate versus when you get a calorie from protein… much different things happen in your body.

So, what actually happens? First and foremost when you eat fat – well let’s talk about an even higher level Carrie. When we eat let’s say one of your delicious SANE ice creams, we don’t have ice cream floating around in our bloodstream.

Carrie: Duh.

Jonathan: I know that sounds stupid but we don’t actually run – our bodies when we eat food, we eat food because there are essential vitamins and minerals and fatty acids and amino acids that we have to have for our body to function. If we don’t have them our body cannot run. It’s like trying to drive a car without gas in the gas tank.

Carrie: I’ve done that.

Jonathan: Yes.

Carrie: It didn’t go so well.

Jonathan: Yes, yes and that analogy actually kind of breaks down a little bit. The gas in the gas tank is probably more analogous to energy or glucose and fatty acids which are the two sources of energy our body can run on. Whereas putting oil, like having your oil changed might be more like vitamins, minerals, essential things like that. So, stepping away from the car analogy for a second…

When we eat any kind of food be it SANE ice cream, be it non-starchy vegetables and nutrient dense proteins, whole food fats or low fructose fruits, those aren’t what our body actually uses for energy and the body has to break it down. So the first step when any food goes into our body obviously we mash it up in our mouth, goes down, ends up in our stomach. But then our stomach does something very, very important it breaks these respective macronutrients.

So there’s macronutrients, protein, carbohydrate, and fat. Then there are micronutrients, vitamins and minerals. It takes these foods and it breaks them down into the next step for lack of better terms because there is no official term. The next step for example, fat is when fat goes into your stomach. It comes in as fat it leaves as triglyceride.

Carrie: Okay.

Jonathan: Okay? Excuse me that is wrong it leaves as fatty acids. Fat comes into your stomach and it leaves as fatty acids. Then when carbohydrate comes into your stomach it gets broken down and it leaves as glucose. Then when protein comes into your stomach it gets broken down and leaves as amino acids.

Carrie: Okay.

Jonathan: So right there, three different things protein, fat, and carbohydrate ending up as fatty acids, amino acids and glucose. One quick side note… if it’s a carbohydrate, it leaves your stomach as glucose. Glucose is a sugar so people say simple carbohydrate, complex carbohydrate, blah, blah, blah, blah, blah. Complex carbohydrate means lots of sugars strung together.

Again this doesn’t mean that carbohydrate is bad for us, it just means that the only difference between a simple carbohydrate and a complex carbohydrate is how long it takes your body to turn it into glucose.

Carrie: Okay.

Jonathan: But it’s still all glucose, right?

Carrie: Got it. That’s an important distinction.

Jonathan: It’s a very important distinction. That process in your stomach takes — each one of these stages burns calories because something is happening your body is doing something. Anytime your body does anything in order for that to happen there has to be energy, right? For anything to change, anything to move we need energy to do that.

That’s important because just like chewing we understand that that burns calories, it takes energy you’re moving your mouth. Digesting food takes energy in fact for the average person about ten percent of the total calories we burn in a day, comes just from the digestive process. So fascinating, right? You burn 2000 calories in a day, 200 calories or the amount of calories you would burn say jogging at a normal rate for about 40 minutes is spent just digesting food.

Carrie: Awesome.

Jonathan: Anyway…

Carrie: You don’t even know it.

Jonathan: You don’t even know it. So you’ve got—

Carrie: I like that kind of exercising.

Jonathan: So protein leaves your stomach its amino acids. Carbohydrate leaves its glucose. Fat leaves it is fatty acids. Now fatty acids are one step away, so fatty acids can be used for energy. Our body’s primary sources of energy are fatty acids or glucose. So, for example if you ate absolutely no glucose. Say you went on an extremely low carbohydrate diet, you weren’t eating any carbohydrate your body would be in a state known as ketosis.

Ketosis just means your body’s running on ketones which is the by-product of fatty acids. Just like we have electric cars and we have gas powered cars you can have a body that is running on glucose, a by-product of carbohydrate digestion or you can have a body that’s running that ketones a by-product of fat metabolism. Make sense?

Carrie: Okay.

Jonathan: Fatty acids are the result of fat going into the stomach. If you have more fatty acids circulating around than you need for energy purposes it is going to get stored as fat because anytime we have more energy than we need our body stores as fat. This is an important thing to note. It might seem obvious but it’s worth calling out. You’re like, “Oh, my god. We’re storing fat. That’s bad.” To be clear, anytime you eat anything unless it’s a tiny, tiny fraction of food.

If you eat a 500 calorie say… lunch you’re going to store fat. Not all 500 of those calories are going to be used immediately. Your body is always storing or burning fat. It’s never not doing one of those two things. That’s okay it’s a balancing act, right? Like the more fat we store our lepton levels change, we’re not hungry then we burn the fat off and our lepton level changes and we get hungry.

It’s a balancing act but keep in mind it’s not like, “Oh, my god. Jonathan said store fat.” That’s not the same as becoming fat. You need to be storing fat short term. Think about it like putting a money…

Carrie: You don’t mean gaining weight fat.

Jonathan: Exactly. It’s like putting money in your checking account that you’re just going to use later in the week versus locking it away in your 401(k).

Carrie: The same thing as accounting, got it.

Jonathan: Fatty acids in the bloodstream, if you have more fatty acids than you need right now that just gets converted through a process where another substance called glycerol-3-phosphate comes into play and now you have triglyceride. The actual fat that sits on your body is a substance known as triglyceride and once you eat fat it turns into fatty acids. If there’s more fatty acids than you need it’s converted into triglyceride.

Part of the reason people think fat is fattening – the following statement is unarguably true. Fat that you eat is very easy for your body to store as triglyceride because it is chemically…

Carrie: Made up of triglyceride.

Jonathan: It is very similar in structure, very, very similar in structure. That doesn’t mean that eating fat will make you gain fat it just means that fat is efficient, the E in SANE. It is the most efficient of the macronutrients. You burn the least calories taking fat and converting it into triglyceride. That is a fact but that doesn’t mean eating fat makes you chronically fat.

Next on the list, carbohydrates. You eat carbohydrate it doesn’t matter where it’s coming from, it doesn’t matter if it’s simple or complex eventually it ends up as glucose. Now the conversion of carbohydrate into glucose is relatively metabolically expensive. It burns quite a few calories, I mean not too many but a decent amount. A decent amount probably like… I think it’s somewhere around the ten percent mark of the calories you eat from carbohydrate may get burnt up in that conversion process.

Maybe a little bit lower but it kind of depends on where they’re coming from. Once you have that glucose floating around in your bloodstream, again it will be used for energy but if you eat more glucose than you need right now it’s going to be stored as body fat. The big difference is that while fatty acids can just go, “Oh, hey, I’m a fatty acid and I find glycerol-3-phosphate, I come together, we make triglyceride we store on your hips.”

Glucose cannot work that way. Glucose, this is why you hear about the hormone insulin so much. Glucose can only get into our fat cells, can only turn into triglyceride if it has insulin to help it out. It needs an escort. Think about insulin as the key that unlocks a fat cell that allows glucose to go in then the glucose needs to be converted into fatty acid, then it is stored as triglyceride, right?

There’s a couple more steps in that process. You can see a carbohydrate is less efficient at being stored as body fat aka triglyceride than fat is because there’s a couple of steps. If you eat carbohydrate it gets converted into glucose, glucose requires insulin to get into the fat cell, it gets in the fat cell gets converted into fatty acids. Then once it’s converted into fatty acids, joins up with glycerol-3-phosphate becomes triglyceride and we’ve got body fat.

You’re going to burn more calories if you ate a 2000 calorie diet and 100 percent of them came from carbohydrate and you didn’t move at all – this is obviously a fictional scenario. You would end up storing less body fat on 100 percent carbohydrate diet that had the same number of calories as 100 percent fat diet.

Carrie: Okay.

Jonathan: Simply because you would be burning more converting carbohydrate into fat, right? It just makes sense that that’s going to happen. Now the reason protein is so effective in fat loss diets or eating styles or studies of whatever you want to do… almost every study that’s ever been done around protein in diet shows that if you swap fat or carbohydrate for protein fat loss ensues.

The reason for that is that protein is extremely inefficient at being stored as body fat. After you eat protein it’s really not a fuel source. Protein is a structural component of your body. Fat is to some extent too, actually a big extent. But protein is really designed to help you build and maintain tissue, not to fuel you. You’ve got fatty acids and you’ve got glucose serving as your primary fuel source. Then you eat protein, protein goes into your stomach, leaves as amino acids.

But just that process right there just going into your stomach and taking protein and turning it into those components, amino acids, is hugely metabolically expensive. You’re talking about 30 percent of the calories you consume from protein are figuratively burnt up in your stomach.

Carrie: Converting it to…

Jonathan: Just converting it into amino acids.

Carrie: Got it.

Jonathan: So the same step for carbohydrates. Again you eat a piece of bread, hopefully not if you’re eating a SANE lifestyle. Then anywhere from five to ten percent of those bread calories are burnt off converting that into glucose. If you just ate pure fat, very little of it would be burnt off because it’s already fats. Protein up to 30 percent of it is getting burnt off in that process.

Carrie: So the net is you have less calories left after you digested protein than if you digested fat or…

Jonathan: Significantly less.

Carrie: Or carbohydrate.

Jonathan: Yes. Significant – like compared to fat anywhere in the… you have ten times more calories getting burnt just in your stomach when you eat protein versus when you eat fat. For carbohydrate it’s probably more like the five to… three to five times more calories being burnt. So just in your stomach there’s a 30 percent sale on protein calories.

Carrie: Got it.

Jonathan: Okay? After that happens, remember protein is not an energy source for the body, it’s a structural building block. You’ve got these amino acids, these amino acids are like, “I want to help you build tissue. I want to repair tissue.” Most people don’t realize this but we are consciously [indiscernible 16:10] cells die, we need to generate new cell, we need to rebuild muscle tissue especially if we’re doing e-centric exercise.

The reason you get sore is you’re literally breaking your muscles down and then we need to build them back up. So that’s what amino acids do. If you eat amino acids ideally they’re going and they’re doing their metabolic duties and they get used for that and that’s it there’s nothing else. They go and they heal you, they repair you, they trigger muscle protein synthesis. All that kind of fun stuff happens.

Now if there is an abundance of amino acids. Let’s say you ate five chicken breasts because you’ve made a bet that you can eat five chicken breasts back to back. It’s very difficult to overeat protein. But let’s say you did, you ate more protein than your body needs. At that point your body’s got to do something with it. It can’t just store protein. Your body really can’t even store glucose. It can store a little bit of glucose like in your muscle cells but for all intents and purposes it can’t really store glucose. Your body stores energy as body fat generally speaking.

So what do you do if you have excess amino acids? Well your body says, “Okay. I’m going to convert it into glucose.” So, those amino acids go into your liver, there’s a process called gluconeogenesis or neo (new), genesis (creation), glucose (glucose), the creation of new glucose. Gluconeogenesis so a bunch more calories are burnt during that chemical change.

Carrie: Good.

Jonathan: Which makes sense, right? Just like it took calories and energy to take chicken breasts and turn it into amino acids, it takes energy to take amino acids and to turn them into sugar which is glucose. That’s kind of just profound for a second. Your body is literally taking water and turning it into wine, right? Not literally but it’s cool.

Carrie: Our bodies are amazing.

Jonathan: It’s metabolic alchemy. It’s taking one substance and turning it into another substance. So it makes sense that you’re going to spend energy doing that. Well now we just have glucose so at this point we follow the same pathway that we would of a carbohydrate but we burn a bunch more calories in our stomach and then we burn a bunch of calories “in our liver.”

So all of that happened and then we still have to go through all the steps that we did with carbohydrate, right? We’ve got the glucose, the glucose needs to meet up with insulin and get into the fat cells, it needs to be converted again, blah, blah, blah, blah, blah. So you have fat which is very efficient, you have carbohydrate which is approximately three times less efficient at being stored as body fat. Then you have protein which is 30 times less efficient at being stored as body fat because it has all those additional steps to go through.

Why does all this seemingly complex science matter? Well the reason it matters — let’s use a very concrete example. Let’s say you ate a 300 calorie snack. If one snack was starch based and another snack was protein based let’s track that through our body.

You’ve got 300 calories of starch. Those go into your stomach. About, let’s say 20 or so, a little less than 20 calories get burnt converting it into sugar or glucose. Now you have 282… conceptually, calories worth of glucose hanging out in your body. Let’s say your body doesn’t need any of that glucose, it’s got enough energy so then it converts that glucose into triglyceride so that it can be stored as body fat, so it ends up being body fat.

You’ve got about 211 calories at the end of the day from carbohydrate that could be stored as body fat. You’re burning about a third approximately, just making those chemical conversions. If you follow that same path for protein you start with 300 calories of protein only 210 leave your stomach versus 282 because about 30 percent of them are going to be lost during digestion. Then we have to convert them into glucose so we lose another approximately 30 percent of that remaining 210 so we’re down to 140.

Then we need to do the same thing we did for carbohydrate to convert that glucose into a substance that can be stored as body fat. That burns another a quarter to a third of those calories so at the end of the day after eating 300 calories of protein, if our body didn’t need it we would have burnt off about 200 of those calories just converting it into a substance that we can store as body fat.

We could store about 200 of the 300 carbohydrate calories as body fat, we can only store about 100 of the protein calories as body fat. Of course if we ate 300 calories of pure fat we could store 290 plus of those calories as body fat. So clearly a calorie isn’t a calorie.

Carrie: So that’s why when I switched to a very high protein diet my muffin top disappeared.

Jonathan: Yes. Just a quick semantic note about very high protein diet, high protein diet.

Carrie: Relative to what I was eating.

Jonathan: Exactly. So what Carrie just described and to get scientific for a second, the term is isocaloric. Meaning if you take diet A and diet B and they both have 1600 calories. Let’s say diet A has twice as many of those calories coming from protein, those are isocaloric diets, and they’re the same. But one has a different macronutrient profile. If everything else is the same in terms of carbohydrate and fat and you just swap fat for protein or you swap carbohydrate for protein, it is metabolically impossible for you to not burn more.

Carrie: Burn fat. Yup.

Jonathan: You have to because your body — don’t do this what I’m going to say is very unhealthy. But if you were to get 100 percent of your calories from protein you’re essentially not giving your body any fuel because remember protein isn’t a fuel it’s a structural component. If your body has to try to use protein as fuel it’s got to go through all this work to be like, “Oh, my god. There’s no fuel. I’ve got to… I’ve got to convert protein.”

That’s actually what happens when we starve ourselves. Our body actually cannibalizes protein we have stored in the form of muscle tissue and it breaks it down into amino acids. Then it converts — so that’s a really painful process. So anyway…

Carrie: That doesn’t sound like a whole bunch of fun.

Jonathan: So Carrie I’m sorry this was more of an academic podcast but hopefully it…

Carrie: It really helped me when I first understood the difference between eating – you know what happened if I ate a Danish pastry versus what happened if I ate a chicken breast. It made it really easy for me to eat more chicken than Danish pastries. It just did. Understanding that scientific why changed everything for me.

Jonathan: There’s no need to argue about a lot of these nutrition related things because biology isn’t a matter of opinion it’s a matter of fact. What we just described here try if possible, not to read too much into it. Just take it for the scientific truth that it is.

For example, fat is efficient, it is. No one can argue with the fact that if you eat fat it’s going to be more easily stored as fat on your body. Okay that makes sense. That doesn’t mean eating fat makes you fat because it’s a much more complicated picture than that. Eating fat also satisfies you. It’s also disgusting to eat fat but no one eats a stick of butter by itself, right? That’s just not how you work but knowing that…

Carrie: We live in such different worlds, such different worlds.

Jonathan: But when you know definitively it is non-debatable that the more of your calories you get from protein, the more calories you will burn just digesting food. That is not a debatable point. That doesn’t mean you should eat 100 percent protein but it does explain why when you start going SANE and when you start getting approximately a third or so of your daily calories from protein versus five percent like some diets recommend you will lose weight while eating more because you’re actually burning more.

Carrie: So… why is it that a SANE lifestyle does not have fat as the enemy? Because it sounds to me, from what you’ve described that fat is the easiest to turn into body fat. So why is sugar the enemy and starch is the enemy and not fat?

Jonathan: Carrie I’m going to have to postpone that because people are like, “Oh, man. That is a great question.” But we’re going to make the listeners have to wait to next week for that one because I want to leave them hanging here because we’ve already gone a little bit over our time and that is an excellent question. So next week folks we will show how despite the fact, despite — this is crazy talk, here, right?

Despite the fact that fat is the least desirable in terms of efficiency, remember SANEity is about all four elements. So not just efficiency. While fat may be the most efficient macronutrient being stored as body fat it’s still a key and important and healthy component of a SANE lifestyle. If that seems like a paradox, tune in next week and we’ll explain why it is not.

Carrie: Well I cannot wait to hear you explain yourself out of that one.

Jonathan: Explain yourself Jonathan. Carrie thank you for the awesome question this week. Listeners, I hope I didn’t get too geeky for you.

Carrie: Thank you for the matching socks.

Jonathan: Well listeners, remember this week and every week after, eat smarter, exercise smarter and live better. We’ll chat with you soon.

Carrie: See ya.

Jonathan: Wait, wait! Don’t stop listening yet.

Carrie: You can get fabulous free SANE recipes over at

Jonathan: And don’t forget, your 100% free Eating and Exercise Quick Start Program as well as free fun daily tips delivered right into your inbox at