Nearly all the stored fat we use as energy is expelled primarily through our lungs when we exhale carbon dioxide and water vapour.
No, really. All of the food you eat can be accounted for by measuring everything that goes in and out of our bodies. There are no mystery calories, and there is no mystery fat gain or fat loss.
If we eat too much, the extra food is stored as fat. If we eat less food than the total energy we burn off in a day, we use our fat stores. We can measure the process of using food for energy in the carbon dioxide we exhale.
This is a normal measurement and is done daily in exercise labs all around the world. I've been looking at this data for decades as a coach, and have had the testing done on myself many times.
It's all about accounting for mass. We know the mass of molecules of carbs, fats, and proteins, and we know how we use the components of those molecules for energy, and we know how much energy is needed to move the mass of our bodies and keep our cells functioning.
It's an energy equation where we are able to accurately account for the mass of what we eat, and the by products of metabolism. It's physics. Don't be misled by corny non-evidence based ideas that don't account for the mass of molecules.
I realize all this molecule stuff doesn't sound as promising or as exciting as the latest "fat loss breakthrough" claims, but it is reality. All the fat loss claims out there are always proven to be fake anyway, so why not cut to the chase?
Learn this reality so you can't be fooled by weight loss gimmicks. And more importantly, if you're trying to lose fat and are feeling frustrated about the process, learn how your body works (for real), so you can lose fat while by-passing the phoney promises, the hype, and all the crooks telling you what you want to hear.
Via a fairly complex chemical pathway, we breakdown fat molecules to make energy, and have some waste products left over, namely water and carbon.
|The fat molecule: a triglyceride (right) is made up of atoms of carbon (black), hydrogen (grey), and oxygen (red). Lot's of these are stuffed into fat cells in our "love handles", and aroud the rest of the body.|
Water and carbon mass, formerly fat in fat cells, former (too much) food on a plate, leaves our bodies through three primary paths.
A very tiny amount of the water is lost in sweat and through the bowel, some is recycled, and a fair amount is also exhaled as water vapour. The vast majority of the mass lost in fat loss goes out, a little bit at a time, in the carbon dioxide we exhale, save for the less than 1% that goes into urine.
Fat doesn't "melt" off, is not converted to muscle, can't be spot reduced with abdominal exercises (or triceps exercises or whatever), and isn't increased or decreased due to different genetics.
You also won't lose fat by exercising in a "fat burning zone", unless you have a calorie deficit, in which case it doesn't matter if you burn fat during exercise or not. Only a calorie deficit, considering all calories consumed VS expended, will result in fat loss. Consider this. If you burn off 500 calories exercising in a fat burning zone, but the total calories you eat is the same as the total calories you expend during the day, no fat loss will occur because you have replaced everything you burned off.
The reasons why this is, are explained here.
We eat food, which has molecules of fat, carbs, and protein, which are made of mostly - you guessed it - carbon, hydrogen, and oxygen atoms. When we eat too much we store the extra as fat (carbon, hydrogen, and oxygen atoms). When we don't use the food molecules we eat as energy, we're literally left holding the bag. We have left over molecules of food with nowhere to go, except our fat cells. That's where we put the overflow.
We don't have anywhere else to put the fat. We can't store it in our heads, though some might argue that some are capable of this feat. There's no room in our bones for lot's of excess fat from chronic overeating. Our blood lipids can increase, but this is really a temporary thing as it takes time to shuttle excess fat to our fat cells. Our blood can't handle all the extra food we overeat - it would simply become too dense and would't be able to be circulated. We have adipocytes (fat cells) in our organs and do store some extra fat there, which is really bad for our health, but the storage capacity in our organs fat cells is very limited compared to the virtually unlimited capacity of our fat cells in our large adipose sites between our muscles and skin. If we fill up our existing fat cells and keep over eating, our bodies just make more fat cells.
We don't poop it out - if we did we would have very oily stool every time we overate fat. Sorry for the detail, just eliminating some of the common guesses out there. When we do the drill down, all extra food we eat can be accounted for in the storage of fat in our fat cells. It simply isn't biologically possible to put it anywhere else. If it were, we'd see obvious evidence of this.
When we use up the stored fat, that mass has to go somewhere, it can't just disappear into nothing, that's not realistic.
Are you breathing? Some of what you are exhaling used to be excess fat. Some of that carbon comes from using carbohydrates and protein as a fuel as well, so not all the carbon we exhale comes exclusively from fat. If you have a calorie deficit, the molecules of fat used to make up for what you didn't eat come from your fat stores and are lost through exhaling carbon dioxide.
Without a caloric deficit or surplus, what you exhale matches what you ate. There is no net gain or loss of fat mass.
Visualize your foods in their microscopic form; a bunch of molecules. Follow the journey of these molecules through your digestive tract and into your body. The molecules will be used for energy by every cell in your body. If you ate more molecules than your cells need for energy that day, the unused molecules are shuttled to your fat cells.
Your living cells use energy 24/7 even if you don't eat enough for the day. Your cells still use molecules of carbohydrate and fat for energy, but when what you eat isn't enough to supply energy needs for the day, your body uses fat stores, and every gram of fat used can be accounted for. You exhale it as carbon dioxide and some water vapour.
Actually, fat is continually shuttled in and out of our fat cells. Kind of like a storage depot that receives and ships out product every day. When our energy consumption matches our energy use, fat cells have no extra fat stored or lost. Like a storage depot receiving 10 boxes but also shipping out 10 boxes. Eat too much, and more fat is stored than used (you receive 10 boxes but your customers only need 6 boxes from you), leaving you with extra inventory. Have a calorie deficit, and more fat leaves the fat cells than is put in, and you lose weight, a few grams at a time. You're always breathing, and when you have a calorie deficit, some of the CO2 you're exhaling comes from fat in your fat cells, even when you're sleeping. You're still burning molecules of sugar, fat, and protein to make energy (measured in calories) when you sleep.
Through being a little more active and eating a little less anyone can create a calorie deficit, and reduce their extra fat inventory. A calorie deficit can't fail at producing fat loss, but we can fail to accurately account for how much we eat and exercise, obscuring the truth of us eating too much.
In case you were curious about how much carbon dioxide mass we exhale- (and I know you are), here are the stats:
About 2.45 grams (0.005 lb) per hour at rest
Between 50 and 90 grams (0.11 - 0.2 lb) per day for the average sedentary person
350 - 400 grams for a moderately active person
600 or 700 grams per day for a very active person exercising 1 - 2 hours per day.
In an hour of moderate to hard exercise the average exerciser will exhale about 350 grams of carbon dioxide (0.8 pounds).
A very active person will blow out about 700 grams of CO2 on the days they exercise for about 90 minutes. That's nearly 2 pounds! This accounts for the equivalent mass of food energy consumed for the day, if there is no weight loss or gain. Despite nearly 2 pounds of CO2 being exhaled, if you eat more than you burn off, the extra goes to fat cells. Kind of like going for a run or going to the gym and justifying eating more because you worked out. Sure, you burned off energy, but if you still eat more than you burn off- fat gain occurs. The gains can be accounted for, as can the losses if you burned off more than you ate.
You don't have to exercise 90 minutes a day to lose fat, I only used that example because it exaggerates the values making it easier to see the difference. 150 minutes of moderate exercise per week and being mindful of reducing food intake is enough.
This exhaling carbon thing has been butchered and abused by diet "gurus" who invent crazy diets that involve, yes, "special" breathing techniques to breathe your fat away. Impossible, of course, but because we can become desperate to lose fat, we can become susceptible to believing these false claims. When you look at the calories recommended in these corny methods, they all use a low calorie diet. They don't address this fact, and use misdirections to convince you "special" foods or food combinations have a magic influence on fat loss. It's eating less, not the "special" claims, that is causing fat loss. The crackpots who push this stuff are gladly being paid by their customers whom they are lying to.
Changing how you breathe has no effect on fat loss. You have to eat fewer calories than you burn off in order for some of the carbon you exhale to result in fat loss.
If we eat as much carbon (from food) as we exhale, our weight will stay the same, no matter how much we breathe or how we breathe.
If we consume less carbon (from food; this is all about eating food, and what happens to it) than we exhale, we lose weight. For many people, weight loss is difficult. People make different claims or assumptions about why this is. When investigated it's always found that people who make such claims or believe in common weight loss fallacies, don't realize they over-report their exercise, and under-report their food consumption. This is easy to do in our overeating culture, and also easy to do when food is habitually used as a reward. You're less likely to want to acknowledge overeating, because that would mean having to deal with eating less, which can feel like getting less reward.
Calories in, calories out. All accountable by adding up the carbon. Sure, it's complicated science to do the measuring to figure all this out, but that's what scientists do. For us, the science is already done, and to benefit from the research, we need to eat less and move more, to achieve a calorie deficit.
While calories in, calories out is the sole equation for fat gain and loss, we also have to be mindful of meeting our energy needs without eating too little or exercising too much in desperation to lose fat. We need a certain amount of food to supply important nutrients, and to meet our healthy minimum energy needs.
Did you know that gas powered cars also use energy stored in hydrocarbons? That's what we're blowing up in the cylinders of our automobile engines; hydrocarbon bonds are in the molecules of gasoline.
Let's say you have 65kg (29.5lb) of gas in your tank when full. Fill your tank, and your car weighs 65kg more. Use half a tank, and you lose 32.5kg of mass. As you burn gas driving, the gas level in the tank goes down, and the car weighs less. Where does the mass go? Out the tail pipe in the form of exhaust. Every kilogram of fuel that goes into your engine can be accounted for in the exhaust.
Lets say you plan on a long road trip, taking a route where there aren't any gas stations for part of the trip. You'll need to fill some gas containers and keep them in the trunk. Kind of like eating too much food and storing extra fat. When the gas tank is near empty, you start using your stored gas, and now you have less gas in the trunk, and your car weighs less. This is analogous to fat loss in people.
What if you had those extra gas containers in the trunk, but then came across a new gas station where you expected none to be? Might as well take advantage and top up the tank right? This might be like someone surprising you with a box of donuts (or whatever unplanned eating). You "take advantage" and add to your fuel stores when you do that. If you don't have extra energy expenditure to burn off the extra, you retain the excess fat stores. If you don't drive off the extra stored gas, It doesn't go anywhere.
Most of us manage our gas use in cars reasonably well, rarely running out of gas. We pay attention to the gas gauge and have a fair idea of how much driving we get out of a tank. Pretty much all of us drive our cars in this way. We're already good at managing the daily energy needs of our cars. If we incorporated this skill into how we eat and exercise, seeing food as energy supply, it makes it easier to understand our food intake/ energy needs. But we can still be find it frustrating to overcome the temptation to overeat.
To lose fat we have to fill up less when we eat so we can use the extra energy we already have stored in our "tank". We still need to replenish our supply of carbohydrates, proteins, essential fats, and vitamins and minerals daily, so cutting back too much deprives us of essential nutrients we need every day. Remember the storage depot analogy, it's a continuous cycle. If we cut off too much of the supply to the storage depot, the depot can't perform it's function because it won't be able to supply its daily baseline customer demands. If we eat too little we can get tired and sick.
The only way to deplete the stored fat is to eat less than we burn off.
Gas mass in, exhaust mass out. Storage depot boxes of product in and out. A couple of analogies that very closely reflect our calories in - out balancing needs.
Carbon-hydrogen bonds, calories, food. Just different words to describe the same thing in greater or lesser technical detail. Calories refer to the energy potential of food.
A lot of the mass of food we eat is not extracted into our bodies through our digestive system. Much of it remains as the bulk that we - leave in the toilet. A lot of the food mass we eat is actually water, so a pound of food doesn't have a pound of carbon in it. For instance, a 70 calorie, 28 gram slice of bread has about 2 grams of fiber and about 11 grams of water. About 40% of a slice of bread has no calories in it, and most of that portion has no carbon in it (the water).
Of the 70ish calories in that slice of bread (mostly from sugars, a tiny bit of fat, and small amount of protein), about 15% of the energy is used for digestion. We're left with about 60 calories worth of energy stored mostly in the carbon-hydrogen bonds of the sugars, fats, and proteins.
Fats, carbs, and protein are each different combinations of carbon, hydrogen, oxygen, and in the case of proteins; nitrogen as well. Fat is the most densely packed.
Like a shrewd accountant, your body can reconcile every molecule of food you eat with every molecule you use for energy and store as fat. There is no metabolism mystery that causes unexplained fat gain, no genetic trait that causes people to gain fat without over eating, no verified accounts of people having a calorie deficit and gaining fat (impossible), and no verified accounts of people having a calorie deficit and not losing fat (also impossible).
The reason I wrote about fat loss from this perspective was to show that fat has a known value. There is no mystery as to what fat is, and where body fat comes from and where it goes. My hope is that I can put a small dent in all the contrived, misleading, misunderstood, and urban myth idea's that are so popular.
I'm not suggesting we focus conceptually carbon atoms to control body fat. That's impractical.
In day to day practical application we’re thinking about portion sizes, number of servings, and matching that up with our activity level. We also need to be mindful of how some foods that fire up our reward centres can cause us to feel really compelled to eat too much. Noting the difference between feeling hungry because you need the energy and feeling a craving because you want the reward of a favoured food is important.
Healthy fat loss is about burning off more than we eat and to do so we need to be mindful of how many calories (food energy) we're consuming. What I offer here is proof of the fact that we know what a "fat roll" is made out of, where it comes from, and where it goes. Creating a caloric deficit works to lose fat, and it works because it can't not work; it works because of physics and chemistry that is real and measurable.
No tricks, no gimmicks, no mystery. We know how this works. Fat loss is explainable. Don't let anyone fool you with weird ideas, alternative facts, or fake news. Be wary; the gimmick pushers are practiced at seeming sincere, know about peoples vulnerability, and know how easy it can be to manipulate a person feeling frustrated and desperate. They make themselves appear as though they are empathetic and are on your side. They know how appealing this can seem. But really they are scammers.
Eat less, move more, and address where your eating motivation comes from.
Mayo Clinic says what I just said here, but they do it in two paragraphs click here
What are you eating? Use eatracker to find out, and Cronometer
Update! Apparently I made a scientific breakthrough without knowing it... - sort of.
A recent study in the British Medical Journal has published a study on this topic, but interestingly, they state that this is a novel perspective on how fat loss works.
Not really, since I posted this article a year before the study was published., - and also... yeah... um... -everything I've written here is standard, basic science- that has been known for several decades.
Study: When somebody loses weight, where does the fat go?
So how do we figure out how much carbon dioxide (CO2) a person is exhaling?
Why, in an exercise lab, of course..
Below is a picture of me in the University of Manitoba's exercise lab having my VO2 max assessed.
The tube in my mouth delivers the gases I breathe in and captures the gasses I breathe out.
In the print out below there is a VCO2 column that shows how much carbon dioxide I was exhaling in liters per minute. At my moderate pace I was exhaling about 330 grams of CO2 per hour, some of the carbon in the CO2 from fat, a lot from carbs, and a little bit from protein.
For you calculating types out there, the density of CO2 is 0.001977 g/mL
This carbon thing isn't my idea, it's proven through science, and we've been measuring this for many decades. It's no secret.
The most challenging part of successful weight loss isn't the mechanics of eating less; it's changing our habits, our thoughts, and our sense of reward with food and exercise. Studies show that the single reason why many people regain fat after losing it- is because they stop the new healthy habits and return to previous overeating habits. The return is made because, as many will be able to concede, it's very difficult to get past the strong internal drive to overeat. I have a lot of posts on how to do this though, so read my blog articles and learn how to lose weight and get fit.
Calorie denial... why we can't face the truth of overeating. Click here for article