Where Does the Fat Go? (And Other Concerns)
If you've ever wondered where fat goes when you lose weight, what exactly a calorie is, and what on earth physics has to do with all of it, this is the episode for you. Today, we talk to Ruben Meerman about the physiology and physics of our bodies. What do atoms have to do with calories? What does carbon dioxide have to do with your waistline? Find out today.
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Guest
Ruben Meerman is a surfer, physicist, and biochemist who has studied weight loss and metabolism through the lens of carbon exhalation.
Checkout his videos and resources on the physics of weight loss on https://rubenmeerman.com/his website.
Ruben’s CO2 Calculator | Food Carbon Calculator | Where Does Fat Go? The Science of Losing Weight.
Takeaways
2:32 - What happens to fat on the body when we are losing weight? Where does the fat go?
When you “burn” anything, it doesn’t just vanish into the ether, it turns into water and carbon dioxide. A similar thing happens to fat as we release it from our fat cells.
Thus, when we are in a calorie deficit, fat gets turned into water and carbon dioxide which gets exhaled.
Energy is neither created nor destroyed. It can only be transformed. When we eat food, the energy is either stored or used.
6:10 - What is a calorie?
First discovered by scientist Antoine Lavoisier putting a guinea pig into a bucket of ice water. A calorie is a measure of energy.
Calorie is the amount of heat that it takes to raise the temperature of a cubic centimeter of water by one degree Celsius, AKA how much energy it takes to raise the temperature of water.
6:53 - How do calories relate to food?
Calories are stored in the bonds between atoms that are holding the food together.
8:23 - Micronutrients include vitamins and minerals. They make up very little of our daily calories
Macronutrients–carbohydrates, protein, fat, alcohol–make up the majority of our daily caloric intake.
Weight loss occurs when. you exhale more carbon atoms than. you are intaking.
When you eat carbohydrates,
Body breaks it down into individual sugar molecules.
Once broken down it travels from the intestine into the bloodstream where it can be broken down into CO2 and water inside the cell. It returns to your blood as CO2 which travels to your lungs and is exhaled.
See graphic from Ruben’s website.
12:04 - If there's more carbon atoms going into your digestive system than you are exhaling from your lungs, you will gain weight that day.
The number of fat cells in your body is the same for your whole life. When you gain weight, your fat cells expand, or ‘inflate” like balloons (AKA they store lipids). When you lose weight and the fat cells release the lipids, the cells shrink, or “deflate.”
Carbohydrates first get stored as glycogen in your muscles and liver. This is what your muscles use for fuel.
Your weight will fluctuate every day due to water weight and that’s okay and normal!
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Juna Okay, Eddie. So we focus a lot on behaviors, right? Yeah.
Eddie I mean, it's kind of the whole premise of the show.
Juna Right. So making better food choices, exercising in the way that makes you feel good, sleeping better, so on and so on.
Eddie Right.
Juna Well, today we're taking a bit of a different tactic. We are going to be talking a little bit more about science.
Eddie What do you mean? We always talk about science. This is, after all, this science based, human laced approach to health and fitness. It's our tagline.
Juna Well, here's the thing. We use scientific terms a lot in the health and fitness spaces, but I think a lot of the time we don't really know what they mean. So today we're going to slow down and define some of what we're talking about.
Eddie Ooh, ah. We're going to do some math and physics. I just need to find my high school Texas Instruments calculator. You know, I probably still have it somewhere.
Juna We're going to be doing just a little bit. Maybe you can leave the calculator out of it this time, but you know, next time maybe we'll use it. Today we are answering the most basic of questions like what is a calorie? What happens to fat on our body when we lose weight? And why do we even need to know this stuff or do we not need to know? I'm not sure. High School Bio Teacher I'm Juna Gjata.
Eddie And I'm Dr. Eddie Phillips, associate professor at Harvard Medical School.
Juna And you're listening to Food, We Need to Talk, the only podcast that has been scientifically proven to burn excess calories just by listening. Let's meet today's guest.
Ruben Meerman I'm Ruben Meerman and I am a physicist by training, but I have become infatuated with biochemistry.
Eddie Oh. We've moved to Australia, mate.
Juna He not only is Ruben Australian, but his nickname is actually the surfing scientist. How Australian is that?
Ruben Meerman When I first started visiting schools, I needed a title and I happened to be a surfer. And because science had a bad reputation, when I 25 years ago, like we were all nerds and dorks, which is still true, but it's a badge of honor now. Whereas when I started it was like, Oh, scientist, yeah, you need to do something about your reputation. Now I recall.
Eddie I go to Harvard. Professors need a cool nickname to make us seem less nerdy.
Juna Eddie, I think you're already so cool. You don't need a nickname. But maybe if you did, we could do, like, the marathon MD or.
Eddie Oh, I love it. Instead of the marathon man. The Marathon Doctor.
Juna Today we're starting with one of the most basic questions on the planet and something that I had truly no idea the answer to before we did this podcast. What happens to fat when we're losing weight? Where does the fat actually go? Ruben got interested in this question from a bit of personal experience.
Ruben Meerman When I was 42 years old, I was a little bit overweight and I just simply decided to lose weight. And I knew absolutely nothing about diets, the diet industry. All I did was do some calorie counting, but it really worked a treat for me. And then as soon as I started losing weight, that's when the question dawned on me, Hey, what's happening to all this mass that I'm losing?
Juna So for a fun little social experiment, the surfing scientist hit the sands, as they say, of Bondi Beach, and asked people where they thought that went. And the answers he got were pretty out there. People said things like into the ether, into the toilet, it turns into sweat moisture, it turns into heat, or it just disappears altogether.
Eddie So basically, nobody has any idea.
Ruben Meerman Yeah, it's the most common misconception that I have heard is that people think fat turns into energy or hating when you're losing weight because we say I'm burning my fat. So for some reason, it's crept into our psyche that when you burn something, it just vanishes and becomes nothing. But actually, when you burn anything organic, whether it's fat in your body or fat in a fire, like if you set olive oil on fire or if you burn anything organic paper wood, it turns into carbon dioxide and water. But those products are invisible. So we just, you know, you think they vanished. They're not part of the universe anymore.
Juna Eddie So I wanted to talk a little bit now about what a calorie is and how it relates to all this stuff, because I'm sure a lot of us are sitting here thinking, what does weight and calories and food have to do with gases in the universe?
Eddie Oh, okay. I think that sounds like a great idea.
Juna But first, it is time.
Eddie It's time for what?
Juna Your most favorite part of the episode, please?
Eddie Oh, yes.
Juna Do the honors.
Eddie And now a brief historical note. Cue the music.
Ruben Meerman In the year 1770. In Australia, Captain Cook sailed into Botany Bay. And so that's a big year for us Australians. And at that point in time humans did not know what a fire is and what happens to the mass that vanishes. And then in 1774, a guy called Joseph Priestley discovered oxygen and there were lots of gases being discovered. But Antoine Lavoisier, who was a French scientist, he put it all together. And by 1788, he had figured it all out and discovered that when you burn anything, the mass that's going missing is turning into carbon dioxide, gas and water vapor.
Eddie And Lavoisier is the man who discovered how to measure calorie. He did this by. Are you ready?
Juna Ready?
Eddie Putting a guinea pig in a bucket of ice.
Juna Whoa. That sounds cold.
Eddie Insulated by snow.
Juna Whoa. That sounds super cold.
Eddie And he would measure how much water was melting in this bucket by measuring the water runoff and using some fancy equations using the water and the guinea pigs' body heat, also known as energy. He defined a calorie. Oh.
Ruben Meerman A calorie. It's such a simple idea, but it confuses people to bits. Lavoisier figured out a really great, clever way to measure what a calorie is, the amount of heat that it takes to raise the temperature of a cubic centimeter of water by one degree Celsius so that it's it's literally just how much energy does it take for me to to raise the temperature of water?
Juna So I think partially why calories in food can be a little bit confusing is because it's hard to understand how something like energy has to do with food, because energy is this really abstract thing and food is this really tangible thing that we can feel in the world, you know?
Eddie So here's something that's crucial to understand. Energy can never be created nor destroyed. It can only be transformed. So when we perceive something is disappearing, it's not really disappearing. It's just changing form. When we eat food, that energy in the food gets transformed in our body into the energy that we then use or we can store. It doesn't just disappear into thin air.
Juna Okay. Well, Eddie, I know you try and help me out, but I have to say, this is the reason I stopped taking physics in college. Like, this is just. This is not my gym I don't like it.
Eddie Okay, let me try to make it a little bit more concrete and bring it back to how we usually talk about calories. And that is in the context of food.
Ruben Meerman In food, the calories are stored in the bonds that hold the atoms all together so they don't fly apart and just float off into the universe. They're all stuck to each other by electromagnetic bonds, and that's where these calories live. My favorite thing to say about this, if you're counting calories, you're by proxy counting atoms because you can't have a calorie in food if there's no atoms there.
Juna Okay. So to recap, calories are a measure of energy, and the energy in food comes from breaking the bonds of the atoms that are holding that food together.
Eddie Sounds easy, right?
Juna Super, super, super simple.
Eddie So now let's talk about what happens when we do our favorite thing. Put food in our mouth.
Juna Yo.
Eddie And actually start eating it.
Ruben Meerman Food has got macro nutrients and micronutrients. If you add up all the micronutrients you need to eat in one day, it adds up to about the same weight as a teaspoon of sugar.
Eddie Micronutrients are things like vitamins and minerals, and they don't contain any calories by macronutrients.
Ruben Meerman So there's hardly any micro nutrients. All of the action for weight loss is in the macronutrients, which is carbohydrates, protein and fat as well as alcohol.
Eddie Remember, weight loss happens when you burn more calories than you consume and macronutrients the carbohydrates, fat and protein, these things do contain calories.
Ruben Meerman Now, if we start with carbohydrates, the clue is in the name. The word carbohydrate stands for the fact that it's made of carbon atoms which have been hydrated by water, which has H2O.
Eddie When you eat a food that's mostly carbohydrate, let's say like a sweet potato or rice or bread or sugar. What happens is that the food goes into your stomach, gets broken down into the individual sugar molecules. And you may have heard of some of these glucose, fructose, lactose.
Juna Okay, but you lost me because I was with you. But then I thought we were talking about carbons. And now I'm confused again.
Eddie We're getting there.
Ruben Meerman Once you've broken them apart, they can travel through the skin of your intestine and go into your bloodstream. And then once they're in there, the only way for those carbon atoms to get back out of your body again is you have to break it all down, turn it into carbon dioxide and water, which happens inside your cells. And once it's carbon dioxide and water, it goes back into your blood. The carbon dioxide comes to your lungs and you breathe it out.
Eddie Do you love it? The elegance of our metabolism. This is why the human body is so incredible. You get something like an apple, which is only solid because it's being held together by the energy and the chemical bonds.
Juna Right through.
Eddie It. Well. Then it goes into your stomach where It's broken down into smaller building blocks. We've been talking about them. The sugar molecules and the sugar molecules get broken down into carbon and water in your cells. Is that not amazing?
Juna Sure. That's that's one word for it. So anyways, to save us all some time and brain space because my head's about to explode, we're not going to go through the other two macronutrients in a lot of detail. But more or less, the important thing to know is that the same thing happens with protein and fats with slight modifications because they come with a few extra atoms.
Eddie Now we hear about calories all the time when we talk about weight loss. It's calories in, calories out calorie balance. But here's another way to think about it.
Ruben Meerman In a day, if you could breathe into a bag and save all of your exhaled breath, you could then figure out precisely how much carbon you have breathed out.
Juna No prob easy peasy. So basically carbon's in carbon's out carbon balance.
Eddie Now if you've eaten more carbon than you've breathed out.
Ruben Meerman So you can turn carbohydrates that you eat the glucose molecules, you can turn those into glycogen, which is a storage form of sugar, and your body has the capacity to hold a few hundred grams of that stuff.
Eddie Juna do you know do you know where your glycogen is stored?
Juna I do know it is in your muscles.
Eddie And your liver. And when we work out, that's where our muscles get their fuel.
Ruben Meerman Once your glycogen stores are chock a block full, then the remaining additional macronutrients that you've eaten, you can you will store those as fat. The point is, if there's more carbon atoms going into your digestive system than you are exhaling from your lungs, you will gain weight that day.
Eddie juna It's this exact process that we're talking about that allow scientists to measure your metabolism in the lab. Have you ever seen those things? We can go into the lab or pay for a service where you wear a mask for a little while and they calculate your resting metabolic rate. Well, the way they're doing it is by measuring the oxygen you're breathing in and the carbon dioxide you're breathing out. And from those two things, they can calculate roughly how many calories you're burning.
Juna Wow. I get it, guys. The stuff is somewhat useful, I suppose sometimes. So if we're breathing all day long, though, I guess that technically means that we're losing weight all day long. In fact, I'm losing weight right now, so I don't even know why we're wasting our time with, like, stupid diets and stuff. How long we should just all breathe harder.
Eddie Okay, okay. Hold on. It doesn't work quite like that.
Ruben Meerman When I talk to audience of people, I'll usually see someone nudging their neighbor and hyperventilating. And then I whisper into their neighbors, Here, look at me, look at me. I'm losing weight and they are losing weight. That's true. But if you keep hyperventilating, you will be breathing out more carbon dioxide than your body is producing. And so slowly, the total carbon dioxide in your body goes lower than it should be. And it's called hypocapnia. And you can faint if you keep doing that, because carbon dioxide actually plays a really fundamental role in your acid base balance.
Juna Okay, so not the best idea to hyperventilate yourself into fainting?
Eddie Probably not. Now look, hyperventilating is not going to increase your metabolic rate, but you want to hear a really easy thing that does.
Juna Sure.
Eddie Standing.
Ruben Meerman The moment you stand up and go and stand in front of a mirror and comb your hair or do anything that way you're standing and just moving your arms. You've now doubled how much carbon dioxide you're producing like 100% on top of what it was while you were lying down, because your leg muscles, a gigantic muscles that need a heck of a lot of energy just to stand you up and move you around.
Eddie And what are we doing right now?
Juna Oh, my gosh. Is this why you always force me to stand in the studio? Because every time I come in here, Eddie guilts me into standing because he's always standing at his podium. And then I feel like a lazy bum if I'm sitting, even though I'm very, very tired. And then I get guilted into standing the whole time.
Eddie Hey, listen, I didn't make you do anything. I just think we sound better when we're on our feet. But, Juna, how about this? You can have, like, 30 seconds of sitting because we're about to take a short break. And then when we come back, you can decide what you want to do. Woo!
Juna I'm going to take a break.
Eddie And we're back and still standing.
Juna Damn it. Anyways, we've talked about the process of weight loss and weight gain and how it actually happens. So now let's talk a little bit more about the cells in our body that actually store that weight, a.k.a. the Faso. So, Edie, what is one of the most common phrases that you hear people who are trying to sell you stuff online say about fat.
Eddie Or the one I love the most is it melts your fat away.
Juna Exactly. Well, this turns out to be a complete myth.
Ruben Meerman Actually, the fat inside our body is always in its liquid state. It never freezes and turns solid. So a fat cell is 80% of its volume is just this blob of fat. And the rest of it is a nucleus with DNA and a few organelles. But the vast majority of the volume of a fat cell is occupied by this blob of fat. And when you're gaining weight, those little blobs of fat get bigger. And when you're losing weight, they're getting smaller.
Eddie In other words, in general, we actually have the same number of fat cells for our entire lives. But when we gain weight, these little cells inflate like balloons filling with lipids. And when we lose weight, they deflate. And that fat turns into carbon dioxide and water like we talked about earlier.
Juna Now, I think a lot of people may be listening and wondering, why do I need to know this? Who cares about the physics of what's happening? And the reason is because when you know the science of how this stuff works, it makes a lot of the lies in the health and fitness industry a lot more obvious.
Eddie One thing that we hear a lot now is calories don't matter. Well, regardless of whether or not you think they matter, at the end of the day, the human body is ruled by the laws of physics, just like everything else in the universe.
Juna Dammit.
Ruben Meerman I can't lose weight is another thing that I've heard many people say. Think about this for a second. If you want to say words, you have to make airflow over your vocal cords so that they vibrate. And so in the process of saying, I can't lose weight, you're losing weight.
Juna For a lot of us on the topics of calories and weight are a little sore. Let's say.
Eddie It is a subject I address gently when talking to patients.
Juna So one thing that talking about these topics more scientifically and really understanding what's going on is that I think it loses some of its emotional charge. Like these processes we've been talking about breaking down molecules, getting extra energy stored in cells, getting some exhale through our lungs. They're not good or bad. They're just biological processes that are happening in the body.
Ruben Meerman In fact, one of the schools I visit is an all girls school, and I speak to girls who are 14 years old. So, you know, here comes a middle aged man who's going to speak to teenage girls about the world's touchiest topic. Their weight, but I don't talk about their weight. I don't mention weight loss for a second. I just talk about, look, when you eat this, there's this many carbon atoms, there's hydrogen atoms. They go in and then they come back out as carbon dioxide. And I do say in there, you know, when people have more carbon atoms than they exhale, their body weight goes up. And that can be a good thing if you're trying to become a bit more muscly.
Juna I can't believe I'm saying this, guys, but even the scale doesn't have to be this massive psychological ordeal if you look at it more like a scientist collecting data. So obviously for a lot of people, weight loss is not a goal. And for a lot of people, weighing themselves is just not a good idea. It always puts them into a mental spiral, you know? Mm hmm. Like, for me, I just remember that it would completely dictate my mood. If the scale went up, then I would have a great day. The scale went down, and I'd have a horrible day. But for other people, weight loss might actually be a goal. And for them, maybe like you don't have to let the scale completely determine your life, you know what I mean?
Eddie But it sounds like treating the scale more like a neutral data stream rather than a dictator of your day might have been better for your mental health.
Juna For sure.
Ruben Meerman I remember doing it myself and I was losing weight. I would also have a really good day if my weight was down and then I'd go, Oh, what happened there if it went up? But you soon figure out what's actually going on with your weight. Every day is it's the amount of water in your body goes up and down quite a bit.
Eddie And if you understand why your weight fluctuates so much from day to day, I don't think you might be quite as upset if you see the scale going up or down a pound or two.
Juna For example, we're always saying on the show to eat more whole foods. And what do whole foods have? A lot of fiber.
Ruben Meerman Look, most of your body weight is water, 60% of it. Some days if you have a meal with a lot of plant fiber in it, then that plant fiber, particularly the soluble kind, which becomes a gel in your intestines. If you've got all this water jelly in your intestines, then the extra. Right that you're seeing on the scales is just that water associated with that gel. And tomorrow, when you have a big trip to the toilet, you'll lose a fair bit of that weight.
Juna Or let's say that you went out with some friends day before and you got some ramen.
Ruben Meerman If you have a very salty meal, then your body's going to retain some water because what you've done is put more salt into your body. And your body only wants to be a very specific kind of saltiness. So if I, you know, I put too much salt in, I need to keep more water so that the concentration of that salt is not too high. And until my kidneys can excrete that water, I'll have put on a little bit of water weight.
Eddie The point is, your weight is going to fluctuate basically every day. And a day to day increase or decrease is not something to draw conclusions from and definitely not something to get emotional about.
Juna Which is easier said than done, but hey, something to strive for.
Ruben Meerman I actually have a very strong suspicion that if we talk about atoms and get away from the potential dangerous psychological territory of body image and just stick with the facts of atoms, then yeah, I think maybe we could save a lot of particularly young women a heck of a lot of anxiety around what's going on inside their body.
Juna So I hope this episode has convinced everyone to not be quite so emotional. Yes, I'm talking to myself about what is going on in our bodies, because at the end of the day, it's all just a bunch of carbon atoms.
Eddie And water.
Juna And jelly in your intestines and water in between your cells from around you.
Eddie And probably not something that we should be getting so upset about.
Juna Exactly. Thank you so much for listening to today's episode. We'll put all links to Ruben Merman's TEDx Talk and his carbon calculator on our website foodweneedtotalk.com. You can find us on Instagram at food. We need to talk. You can find me on Instagram @theofficialjuna and Juna Gjata on YouTube and Tik-Tok. You can find Eddie breathing into a paper bag to measure the carbon atoms he is emitting. Food We Need to talk is a production of PRX.
Eddie Our producers are Morgan Flannery and Rebecca Seidel.
Juna Tommy Bazarian is our mix engineer with production assistance from Isabel Kirby McGowan.
Eddie Jocelyn Gonzalez is executive producer for PRX Productions.
Juna Food We Need to Talk was co-created by Carrie Goldberg, George Hicks, Eddie Phillips and me.
Eddie For any personal health questions, please consult your personal health provider to find out more, go to foodweneedtotalk.com Thanks for listening.
