How Your Metabolism & Calories Work & How to Lose or Gain Weight
Every once in a while it’s good to go deep into a topic to really understand what’s going on. Today is one of those days.
It will be a practical discussion and hopefully by the end you have a great understanding of what calories really are, why you need them, how to know how many you need, and why it’s important to take losing or gaining weight seriously (and how to do it right).
Metabolism, Calories and Energy Balance is a fairly complicated topic with a lot of terminology, intertwined pieces and a decent amount of science. Unless you are “into it” there’s really no reason why you’d know the nitty gritty ins and outs. When you see TV segments on health and fitness on morning TV or in headlines on magazines they certainly can’t spend the time to thoroughly explain things. Most of the time when I see these segments I’m not convinced that the “special guest” even knows the things that you’re about to learn today.
Speaking of what you’re going to learn today, let’s lay that out.
We’re going to talk about:
What Calories Are And How They Are Measured
The Caloric Content of The Three Macronutrients
Why We Eat & How We Turn Food Into Energy
How Our Body Uses The Calories That We Eat (TDEE)
How To Determine Your TDEE
What Happens When You Eat More Calories Than You Need
What Happens When You Eat Less Calories Than You Need
How The Body Adapts to Increases & Decreases In Calories (Metabolic Adaptation)
How to Use This Knowledge To Your Advantage
Buckle up buttercup and let’s go!
What Calories Are And How They Are Measured
You can’t talk about food, metabolism and nutrition without discussing calories. Some people think calories don’t matter at all and some people think they’re all that matters. Spoiler alert: They matter, but they’re not all that matters.
No matter where you fall on the spectrum of calorie belief, let’s define what they are. If you had a microscope and could zoom in realllllly close on a cookie you’d see these little calorie soldiers walking around just waiting to get into your belly and make you fat.
Just kidding. A calorie is just a unit of measurement (energy in this case). A way to assign a value just like a gallon, a mile or a teaspoon.
More specifically, a calorie (small c) is the amount of energy it takes to raise a gram of water 1 degree celsius (from 14.5 to 15.5).
When we reference this in terms of nutrition, one Calorie (capital C) contains 1,000 of these calories (small c). That’s why nutritional Calories are often referred to as Kilocalories or Kcals (Kilo = 1000)
Yeah, but how do we know how many of these units of energy are in the foods that we eat? Luckily, food companies are required to divulge this information to us on food packaging because of the Nutrition & Food Labeling act of 1990. But maybe you’re wondering how the food companies and scientists come to learn how many Calories are actually in those foods.
Wonder no more. Now this part might sound like a joke but it’s true. Nutrition scientists use a tool called a Bomb Calorimeter (yes that’s a real thing) to measure the caloric content of foods.
Within the calorimeter are two chambers, one inside the other. Food is weighed and then placed in the inner chamber, along with oxygen (which is combustible) and then sealed. The outer chamber is then filled with water. The oxygen is ignited and the food in the inner chamber is burned. As the food burns, the scientist monitors the rise in water temperature in the outer chamber. If the water temperature rises 1 degree per kilogram of food weight, that = 1 Calorie in the food. 2 degree rise per kilo = 2 calories and so on. So foods that are higher in Calories will raise the water temperature in the outer chamber as they burn more than lower calorie foods. How freakin’ cool is that?
The Caloric Content of The Three Macronutrients
So now we know what a Calorie is, and how the caloric content of food is measured. I’m sure in reading food labels and just from plain ol’ common sense you’ve noticed that certain foods are much higher than others in calories. The reason that’s the case is because different foods contain different amounts of the 3 Macronutrients (Protein, Carbohydrates and Fat) and each of those macronutrients has different amounts of calories per gram of weight. (Remember back to the Bomb Calorimeter).
Luckily for food manufacturers, researchers and the USDA have developed tables based on measuring thousands of individual ingredients breaking down their macronutrient and thus Calorie content. This keeps companies from having to use a bomb calorimeter for each food item.
The current widely accepted caloric content of the 3 Macronutriets are:
1 Gram of Protein contains 4 Calories
1 Gram of Carbohydrates contains 4 Calories
1 Gram of Fat contains 9 Calories
So obviously, two foods that weigh the same might have totally different amounts of Calories depending on what Macronutrients are in the food.
In case you’ve forgotten… Protein is mainly contained in mainly in animal products, Carbohydrates come mostly from sugars, fruits, vegetables, grains, and legumes and fats are mainly contained in oils, non-lean meats and dairy.
Let’s look at an easy real life example using a can of black beans.
The label says that a serving of beans weighs 125g. According to the label, that 125g contains 7g of protein, 20g of carbohydrates and no fat. Since we know that both protein and carbohydrates contain 4 calories per gram, we can add 20+7 (27) and multiply by 4 to find out how many calories are in the serving. 108 Calories. If you’ve ever tracked your food intake in an app like MyFitnessPal you have noticed that this calculation doesn’t always exactly match the label. The reason that happens is because labels are not required to use decimal points which causes some rounding discrepancies from time to time. Don’t get too hung up on that. Your health does not swing in the balance of 2 or 3 calories per food.
Alright we better keep moving or this is going to end up being longer than Gone With The Wind.
Why We Eat & How We Turn Food Into Energy
Other than the fact that food is delicious, why do we need to eat it? Well quite simply, because it contains those energy containing macronutrients that we just finished learning about. Just like a 747 runs on jet fuel, our bodies run on Calories. EVERY process within our body from digestion to doing a burpee derives it’s energy from calories. Pretty wild that we get to choose from an endless list of foods to provide ourselves with energy right? But even with that variety, all our bodies care about at the end of the day is that it gets that energy (Calories) from somewhere.
Since you can’t drop by 5 Guys and order a “Calorie Burger w/ Fries” our bodies have to take the food that we eat and convert the macronutrients in it into energy that our body knows how to use. We call this whole umbrella of food to energy conversion our Metabolism.
There are 4 major methods our bodies use to convert food to energy. The final product of these conversions is called ATP (Adenosine Triphosphate). ATP is required for all cellular functions and has many roles in the body, but for our purposes today we’re going to focus on the big one. ATP is used to power all of the mechanical functions of our bodies. You know moving around and doing stuff! But before we get into that let’s back up and look at those conversion processes.
When we eat, our bodies immediately start digesting our food. Even in our mouths. Through cellular respiration, the sugars (glucose) that naturally occur in foods are converted into ATP. It’s a much more complicated process than that involving oxygen, carbon dioxide and water, but it’s important to note that glucose plays a vital role in this process. Foods containing carbohydrates are our main sources of glucose. As ATP is generated it’s stored in our muscles to be drawn up on for energy demands. We don’t store a whole lot of it, so our bodies are always synthesizing new ATP to keep us fueled (If we’re eating food).
Ok, let’s regroup. We’ve learned what a Calorie is and how they’re measured. We’ve talked about how food contains different amounts of each of the 3 macronutrients and how that affects how many Calories are in the food we eat. We talked about the fact that our body needs to convert food into energy and how that’s done.
How Our Body Uses The Calories That We Eat (TDEE)
We talked at the very beginning about how our bodies need calories to perform alllllll of the many functions that we ask of them, so let’s dig into that and get specific. One fascinating thing about nutrition is how much variability there is from person to person. There is no way to say that every person’s nutrition should look the same, because we are all so different. We have different jobs. We have different habits. We have different activity levels. We have different weights and heights. We have different genetics. We have different experiences with “diets” that have affected the way our bodies use energy. All of this adds up the fact that we all have a different amount of energy that our body needs to exist at our current size and activity level.
We have a name for this idea. It’s called our Total Daily Energy Expenditure (TDEE). This is the total energy, measured in Calories that you need to maintain your current body size, at your current activity level. Remember how we talked earlier about how our bodies use energy for the different things we do from sleeping to digesting to running a marathon? All of those activities, whether they are voluntary or involuntary use calories. When you add up all of the calories each day that are burned to accomplish these things, that equals our TDEE. If food is “calories in” to our body, TDEE is “calories out” of our body. This relationship between “in and out” is called energy balance. We’ll talk more about that later.
All of those calories burned in our TDEE can be broken up into 4 basic categories:
Basal Metabolic Rate (BMR)
Non Exercise Activity Thermogenesis (NEAT) & Non Exercise Physical Activity (NEPA)
Exercise Activity (EA)
Thermic Effect of Food (TEF)
Let’s talk about the big boy first, BMR. It’s the big boy because it devours about 60% of daily energy.
Think of your BMR as all of the things your body has to to do just keep you alive even if you just laid in bed all day. It’s the bare minimum number of calories you’re going to burn even doing nothing.
Some of the elements of your BMR include:
Breathing
Circulating Blood
Regulating Body Temperature
Cell Growth
Brain & Nerve Function
Moving on to the next “biggest” part of your TDEE we have NEAT/NEPA. These account for about 15% of your TDEE or your total daily calorie burn. These NON-EXERCISE calories are burned doing things like blinking, fidgeting, using your phone and computer, and other non-exercise movement like standing or walking from task to task. The #1 thing we want you to remember about NEAT is that it is highly adaptable. What we mean is that since so much of NEAT is involuntary, your body will auto regulate how much NEAT you “do” based on how much energy you’re putting into your body. We’ll go into this more later when we talk about what happens when you eat more or less than your body needs. Remember, your NEAT is NOT set in stone.
Alrighty, let’s move on to what is undoubtedly the most OVER estimated category when it comes to calorie burn. Exercise activity (EA). This one is highly variable from person to person because well, some people exercise a lot and some people are more into sleeping in and chillin’ on the couch with the Netflix. But even if you are the exercising type it’s easy to overestimate how many calories you’re burning through exercise. This is especially true if you’re counting on the reading from an activity tracker like an Apple Watch, FitBit, Garmin or Whoop Band. Unfortunately these devices are notoriously inaccurate despite recent improvements. Exercising is generally NOT a reason to eat more because of the Calories burned doing it. Here’s why.
Estimated calories burned for a 150-lb person:
One Hour Brisk Walk - 260 Calories
Thirty Minute Jog - 280 Calories
Thirty Minutes of Aerobics - 225 Calories
Thirty Minutes of Circuit Training - 280 Calories
Of course we aren’t telling you that exercising is a bad idea or that you shouldn’t be doing it multiple times per week. You should be! But you should be doing so with the intent of improving your health, fitness, strength, confidence and longevity, not to count how many calories you’re burning. You’d be hard pressed to find a protein bar that contains less than 200 calories, and that’s considered a “healthy” snack.
Since it’s Girl Scout Cookie season…
There are 160 calories in just 4 Thin Mints.
Has anyone actually ever eaten only 4 of those little things?
It would take me exactly 67 seconds to eat 8 of those little devils.
That would mean I’d have to walk for well over an hour to burn off those calories.
Can you see why you cannot “out exercise” a high calorie diet? There aren’t enough hours in the day when you start talking about foods like pizza and chicken wings. For the average person, Exercise Activity accounts for about 15% of their TDEE.
Ok, let’s talk about the last, and most often unknown about element of TDEE. The Thermic Effect of Food (TEF). Before becoming a nutrition coach and dedicating time to learning about the science of nutrition I had no clue about this one. TEF is the energy used by your body while extracting the energy from your food. Sounds like some Inception stuff right? Think about it like this: Your car runs on gas to make power. The goal is to make the wheels turn, but there’s a lot of wasted energy in the many processes between the gas tank and the tires. In the same way, your body producing energy (ATP) costs calories during that process. The interesting thing to know is that the 3 Macronutrients don’t have the same “cost” to digest and obtain energy from. For our purposes here, you should know that protein and fiber “cost” the most when it comes to extracting their nutrients. What that means to us in practice is that we will burn more calories eating protein and fiber than carbohydrates (other than fiber) and fat. Overall, TEF makes up about 10-15% of our TDEE. So even though the impact of TEF is not huge in the grand scheme of our TDEE, paying attention to our protein and fiber intake can often move the needle in situations when we’ve hit a weight loss plateau.
How To Determine Your TDEE
By now maybe you’re wondering “How the heck am I supposed to know what my TDEE is?” Great question! Before we tell you how to find your TDEE we need to establish that your TDEE isn’t a set in stone number. It’s not set in stone from day to day and it’s not set in stone from year to year. Oh yeah, everyone’s is different too! I’m sure that makes sense if you remember all of those variables that make up TDEE. Also, us humans are adaptable animals. Our bodies adapt the stresses we expose them too. They also adapt to the amount of energy that we put into them. This is another reason that your TDEE is a number that can change over time. Our bodies crave homeostasis. We use our adaptable ability to achieve energy homeostasis through our ever evolving TDEE. More on that later too!
Ok, so here’s how to figure out (or at least get close to figuring out) your TDEE. The fastest way is to use you fingers. Google “Mifflin-St Jeor Formula” calculator. This is a widely accepted formula to determine your BMR based on your Sex, Age, Height and Weight. From there we need to add in some calories to account for our activity (remember NEAT and EA?). We do that through an activity multiplier. Take your BMR and multiply it by one of these that fits best:
Are you sedentary? BMR x 1.2
Do you do light exercise 1-3 times a week? BMR x 1.375
Do you do moderate exercise 3-5 times a week? BMR x 1.55
Are you very active 6-7 times a week? BMR x 1.725
Are an athlete who exercises 2 times per day? BMR x 1.9
WARNING: Most people over estimate how active they are and how intensely they exercise. When in doubt, be conservative in your estimation. You are not Michael Phelps.
So that number you came up with after you used your activity multiplier is your estimated TDEE based on the calculations. Easy enough right? For some people this number is “good enough”. It’s certainly a starting point. But there are drawbacks and limitations to this method. It doesn’t know much about “you”. It doesn’t know your previous experience with diets. It doesn’t take into account how many calories you’re eating now. It doesn’t take into account your body fat percentage and your habits. All of these things have an impact on your TDEE. So while calculators are a convenient shortcut, they don’t always tell the truth. We’ve learned from working with many clients over the years that these calculators can routinely be off by 10-25%.
Here’s the other way that find your TDEE that doesn’t use a calculator, but does require more effort on your part. The benefit of that extra effort is that it’s based more on YOU, therefore the results can be trusted. Here’s what you need to do, step by step.
Get a cheap digital food scale like THIS.
Get a smart phone or a computer and download MyFitnessPal or go to www.myfitnesspal.com and set up an account.
Read THIS article we wrote about to use MyFitnessPal without screwing it up.
Weigh yourself and record your body weight in MyFitnessPal.
WITHOUT CHANGING YOUR DIET, log EVERYTHING you eat and drink in the app for 5-7 days. The point is to see where your energy needs are currently, so if you are feeling guilty about your choices and choose not to log a few handfuls of candy that you normally eat each afternoon you’re not going to get an accurate estimate of your TDEE.
Maintain your “normal” physical activity and exercise during these days also. Don’t do this when you’re sick or when you decide that you’re goi=‘\ng to start running 5 miles per day when you’ve not been doing it previously.
After your 5-7 days of logging your food, take your body weight again and record it. Add up the total number of calories that you ate and divide by number of days that you logged. For example if you logged for 5 days and ate a total of 10,000 calories, your average daily calorie intake was 2,000 Calories.
Assuming that your body weight stayed about the same (plus or minus a pound) and you did a good job logging your food, you now have an accurate estimate of your TDEE. Since this is based on an average, the more days you log, the better your estimate will be.
If you weigh yourself at the end of your food logging and you’ve gained a large amount of weight (2-5lbs) I would recommend trying again. What else ya got to do? I mean, you’re going to be eating anyway right? 🙂
We have covered a lot of ground already. If you need to go use the restroom or refill your coffee I’ll wait here. Ok welcome back.
YOU AND YOUR TDEE
Now that we know our TDEE, let’s talk about how that relates to how much we’re eating. We already discussed that our TDEE changes over time. It’s also important to know that we’re talking in terms of time longer than one single day. It’s difficult to gain or lose a significant amount of weight in 1 day regardless of your TDEE unless you’re eating hot dogs in the Nathan’s Hot Dog Eating Contest. We’re talking about what happens when you eat different amounts as an average over longer periods of time like weeks, months and years.
Ok, let’s move on and talk about 3 different scenarios:
WHAT HAPPENS WHEN YOU EAT AT YOUR TDEE - Calories in = Calories Out - Maintenance
This one’s easy. When you eat (in calories) at your TDEE, your body weight remains unchanged (besides daily fluctuations) and there is little to no effect on hormones in the big picture. Again, this is based on your average intake, not 1 day. Eating at your TDEE can be a good “break” for your body if you’ve been chronically dieting. It’s a way to restore hormonal balance, minimize metabolic adaptation and give your mind a break too. We’ll get into that later.
WHAT HAPPENS WHEN YOU EAT MORE THAN YOUR TDEE - Calories in > Calories Out - Caloric Surplus
On the surface this one is simple. When you eat more calories on average than your TDEE you gain weight. But there’s more to the story. I’m sure you know that over eating causes fat gain. Ever wonder why that is? Remember how we discussed that fat is more calorically dense than carbohydrates or protein? That makes fat (lipids) an extremely efficient storage medium. Throughout our evolution, food has not always been as readily accessible as it is now and our biological processes reflect that. We have the ability to store extra energy that we eat so that we have a backup in times of low energy intake. If we routinely eat more than we need our body converts that surplus of energy into body fat. Here’s how it happens.
Eat Food
Insulin is secreted by the pancreas
Insulin signals the cells in our muscles, liver and fat cells (others too) to start building proteins (muscle) from the amino acids, convert the sugar (carbohydrates) to glucose/glycogen and convert dietary fat to triglycerides.
If we’re eating AT our TDEE, it all comes out in the wash and these processes don’t result in fat storage for later use. When we are eating more than our TDEE, our bodies store the extra energy in our fat cells. But there’s some nuance that you should know about.
Our bodies aren’t great at storing excess protein and carbohydrates as fat. We can absolutely do it, but not nearly as well as we can store excess fat as body fat. It can require up to 10x more energy for our body to store carbohydrate and protein as fat excess dietary fat. What does that mean on a practical level? Well if you know you’re going to be eating more than your TDEE, and you’re not keen on storing the extra energy in your waist and thighs, try to skew your extra intake toward protein and carbs vs. fat. Please notice that I did not say a calories made up of protein and carbs CANNOT be stored as fat, rather it’s just a less efficient process. If you chronically over eat ANY of the 3 macronutrients you will gain weight and fat. Are we clear? :)
Eating more than your TDEE is a necessity if your goal is to build muscle. Our bodies require the energy from calories to build new tissue. If we aren’t eating more than our TDEE we will lack the surplus of energy beyond our minimum needs to build new muscle. Since protein contains the amino acids that are the building blocks of muscle it’s important to consume enough protein when eating in a surplus to build muscle. We recommend ~ .8-1.2g of protein per day per lb of body weight. The exception to that would be rank novice trainee or someone that has not trained appropriately before. These subjects are able to build muscle while eating at, or slightly less than their TDEE. We wrote an article about that HERE. The other critical element to building muscle in a caloric surplus is resistance training. If you’re over eating and not lifting weights, you’re doing it wrong.
We’ve talked about 2 things that happen on the outside of your body when you eat more than your TDEE, how about what happens on the inside?
Remember NEAT? That non-exercise activity that burns up a lot of the calories you use during the day? NEAT is the most adaptable element of our metabolism and TDEE. The biggest thing that makes it go up and down over the course of days, weeks and months is the energy available to power all that activity. When energy is abundant, expect a sharp incline in NEAT. This usually manifests as generally feeling more “energetic”. Walking out the get the trash can is no big deal. Sinking deep into the couch and going comatose doesn’t sound as appealing. The effects on NEAT from a caloric surplus are noticeable.
A caloric surplus also acts on the 2 main hormones that affect our hunger and satiety. They are Leptin and Ghrelin. Leptin tells us “you’re not hungry” and Ghrelin sends signals of hunger to our brains. These two hormones work in opposition to each other. We secrete more Leptin when we over eat which suppresses hunger in an effort to help us maintain our current weight. So as you eat more than your TDEE your body tries to bring you back to homeostasis by telling you “Hey, I’m full!”. As you might have experienced, it’s possible to power through those signals and keep eating. Happy Thanksgiving 🙂
Another thing that happens as we chronically eat more than our TDEE is that our bodies become LESS efficient at using energy. Think about it this way, if you had a magic wallet that seemed to never run out of cash, how efficient would you be in your spending? I’m guessing you wouldn’t think twice about dropping $5 for a fancy ass coffee or $25 for a hat that you may or may not wear. When resources are abundant, we’re less careful with them. We tend to waste more.
The same is true with the energy conversion in our bodies. If we get used to a bountiful energy supply, who cares if we waste a little in the process. What this means is that our TDEE can gradually creep higher and higher when we’re over eating.
That leads me to the next point. As you eat more than your TDEE you’re going to gain weight. If you take the smart approach and consume adequate protein and lift weights in the right way you’ll gain muscle in addition to fat, but either way you are becoming a bigger person. Guess what a bigger person needs? More calories. When you figured out your TDEE you were one weight. As you’ve eaten and grown, you’re a greater weight. That means it takes more energy to move around those extra pounds, more energy to digest and absorb that extra food you’re eating and more energy to do your workouts with those larger more powerful muscles. All of this means that whatever your TDEE was 6 months ago is NOT what it is today if you’ve been eating in a caloric surplus. You’re not the same person anymore. If you’ve gained significant weight and want to see where your TDEE is now, you can follow the same steps we outlined earlier.
What happens when…
You eat less than your TDEE - Calories In < Calories Out - Caloric Deficit
This situation is known as a “diet” in common nomenclature. Eating less than your TDEE (calorie deficit) is the reason that any successful “diet” makes you lose weight. Yes, I said ANY diet. Even that magic fad diet that you saw on The Today Show or on the cover of a magazine at the grocery store check out. Let’s talk about why that’s true. When we’re eating AT our TDEE our body uses the available energy from the food we’re eating to provide everything we need. There is no body fat storage or utilization. When we eat less than our TDEE our body can now tap into our reserve energy. Our body fat. Our reserve energy is stored in fat cells called adipocytes. Since we’re not eating all of the time, fatty acids are going in and out of our fat cells and blood to provide us energy all the time. This is largely dictated by when the last time we’ve eaten is and the subsequent release of insulin. When we run our body short on energy in the longer term (not just between meals) is when we really tap into our fat reserves. Through a series of processes, fat, in the form of fatty acids is shuttled from the adipocytes, through the blood stream and into our muscles to be burned for energy. This liberation of fatty acids from the adipocytes reduces their size. They shrink and give you visual benefit of “fat loss”.
But just like the internal processes that happen when you over consume calories, there are internal things that happen when you under consume calories.
Let’s go back to NEAT. The opposite effects of NEAT can be seen in a prolonged caloric deficit than the ones we discussed earlier. Remember, our bodies want homeostasis. They want to stay the same. If we’re giving our body less energy (Calories) than it needs it’s going to try to make up the difference. A reduction of calories burned through NEAT is arguably the most notable change you’ll experience when dieting. As with all things nutrition, there are individual differences from person to person but as you decrease your calorie intake and as a period of calorie deficit rolls on, you will likely feel less energetic. You may move less. The idea of getting off the couch to get the remote sounds less appealing than sitting through a commercial. Some of the declines in NEAT will be very noticeable and some not so much. The deeper you go into a caloric deficit and the longer you keep it up the “worse” it will get. I’ve heard tales of professional body builders that obtain dangerously low body fat percentages feeling like they were BLINKING slower than normal just before they got on stage for a show. Ouch.
In addition to a decline in NEAT, our body will also down regulate our BMR in an effort to consume energy. Everything. Slows. Down. Remember, our body wants homeostasis and will do it’s best to achieve it.
The same hormones that are in play in a caloric surplus are also at work in a caloric deficit. In an energy shortage, Ghrelin secretion is ramped up which increases our hunger. That makes your brain tell you “You need to eat something!”. During this time, Leptin secretion from the fat cells is reduced also. Remember, leptin tells you that you’re full. So you’ve got one hormone telling your brain that you need eat and another hormone telling your brain that you’re not full. Double ouch! These hormones are one of the reasons that losing weight gets so tough. Other hormones like testosterone and estrogen are shown to change in a caloric deficit also, although they have less overall affect on overall metabolism of energy. The stress hormone Cortisol has been shown to increase in times of prolonged caloric restriction. This typically manifest in higher irritability, fatigue and overall decreased mood.
Let’s talk about what happens to our energy needs as we lose weight/fat through a calorie deficit. If our TDEE increases over time as we GAIN weight through a caloric surplus, you can probably guess what happens as we LOSE weight. That’s right, we need LESS energy to maintain our current size. As a lighter person you no longer require the same number of calories to power your body. Combine that with the decreased energy demands from a decline in BMR and NEAT and over time you just need less food (energy) as you diet. This probably makes sense to you, but there’s an important connection that I want you to make in your brain regarding this. Over time as you eat less than your TDEE your TDEE gradually gets less and less THIS is what causes you to stop losing weight on a diet even though you’re still eating the same number of calories that you were when you started the diet. What used to be a caloric deficit for you is now your TDEE. This is what causes weight loss “plateaus”. When your caloric deficit is no longer an actual deficit, but rather it’s now your maintenance.
Another important thing to point out is that weight loss does not necessarily mean FAT loss. Yes, your body WILL tap into your fat reserves in a caloric deficit. but it can and will also tap into stored energy in the form of muscle also. That’s not good, as muscle is not easy to build and it’s our greatest fat burning engine. Minimizing muscle loss during a caloric deficit is important, but it’s not complicated. Consuming adequate dietary protein (.8-1.2g per day per lb that you weigh) and resistance training 3-5x per week is the not-so secret recipe to preserving as much muscle as possible during a diet. You should do both.
Summary, Metabolic Adaptation & How To Do This The Right Way
Although we discussed each of these within each section above I think we should summarize and bring up a few more things. Our bodies are VERY adaptable and because of that very individualized. There are universal elements of nutrition like energy balance (calories in vs. calories out), the science behind fat storage and hormone secretion and the roles of protein, carbohydrates, fat and fiber in our body. These hold true for everyone (unless their is an underlying condition or disease). Then there is individualization of all of these elements that are more specific from person to person. We rely up on the scientific basics as we guide “real people” through their own application of these facts.
The adaptable capabilities of our bodies provides us with amazing opportunities, but also places a responsibility on us to try and have as little impact on our natural systems as possible.
Unfortunately we live in a culture of quick fixes, shortcuts, fads and general misinformation that preys on people’s lack of knowledge and desire to get results with as little inconvenience as possible. This has contributed to the epidemic of yo-yo dieting, chronic disease, obesity and unnecessary metabolic adaptation.
You see, we have the ability through going on and off extreme diets to wreak a little big of havoc on our hormones and metabolism. Our bodies don’t like extremes and they’re prepared to deal with them in extremes. When we go from eating at or above our TDEE for a prolonged period straight into an extreme caloric deficit we’re effectively telling our body that we’re starving. Energy is NOT readily available. It uses those adaptable features we discussed earlier to try and regulate our weight and energy usage. Declining our BMR, NEAT, TDEE and using our hormones to try and get us to eat more are among the tools it has available. Those hormones also send a signal to our fat cells. The cells become prepared to store fat quickly and efficiently should energy become available again soon. Not only that, but in some cases studies have shown that we can generate NEW fat cells to store even more energy for future use.
What’s the big deal you ask? Think about this. If you rapidly change your diet (maybe remove an entire macronutrient from your diet or decide you’re only going to drink juice) which in turn helps you create a calorie deficit which makes you lose weight, how long can you keep that up? Is that sustainable? If you have an event on the horizon that you want to look your best for so you slash 800 calories per day out of your diet, putting you into a deep caloric deficit, what are you going to do after the event? In both cases you lost weight, but you’ve also set yourself up for rapid weight gain once your plan is no longer sustainable. How many times have you or someone you know lost 20 lbs, then regained 25. Then lost 15, and gained back 18. This is yo-yo dieting in an unsustainable way. It’s not good.
The really bad part of that approach is that triggering your body to adapt to decreased energy over and over again increases it’s efficiency to prevent you from losing weight. It just makes sense from an evolutionary stand point. Yo-Yo dieting is not healthy for your mind, or your metabolism and it’s setting you up for long term failure and frustration.
The term “metabolic damage” gets thrown around these days. I prefer to think of it not so much as “damage” but metabolic adaptation that needs a little love. It’s possible to reverse the negative adaptations we can do to our bodies if we are patient and use smart strategies. It’s also possible to lose and gain weight in a way that lessens the amount of metabolic adaption and “triggering” of your bodies built in self-defense mechanisms that prevent weight gain or loss.
If you’ve dieted with extremely low calories for a prolonged period you might find yourself unable to keep losing weight, despite still having quite a bit of weight to lose. In these cases, cutting more calories just isn’t practical. Your TDEE is already very low for your body weight and you’re likely feeling the other feelings like lack of energy from metabolic adaptation. If this sounds like you, you need to wrap your mind around the idea of gradually eating more food over time (slowly) in order to reset your hormonal balance and bring your TDEE back up into normal range. If you do this slowly over the course of months you can take advance of your increases in BMR and NEAT and not gain as much weight as you would if you were simply add several hundred calories per day all at once. Once you’ve adapted to a more normal caloric intake and your biofeedback is looking good, THEN you can start to work your way back into a caloric deficit to lose more fat. This process is called a “Reverse Diet”. We talk a bit more about THIS article.
If you’ve been eating at or about at your TDEE for a prolonged period you’re in a good spot to start a caloric deficit to lose fat. Remember, your overall goal should be to lose fat in a manner that minimizes the amount of adaptation that your body makes. We want to try not to give your body that “oh crap we’re starving moment”. Our preferred method for this is 2 fold. First, we want to set a moderate, but not overly aggressive calorie deficit. The actual number depends on where your TDEE is now and how much weight you have to lose. We know that there is roughly 3500 Calories of energy in a pound of body fat so we use that knowledge to subtract calories from their weekly TDEE and then average that out into a daily calorie goal. So if our goal is to lose 1lb per week, we need to create a 500 calorie per day deficit on average (3500/7 = 500). In general, a caloric deficit that produces a conservative rate of fat loss (.5-1% per week will be more sustainable and have less metabolic impact than a more aggressive approach that attempts great rates of fat loss.
The second thing we consider when helping a client lose weight is the short term and total period of time spent in a caloric deficit. Dieting is a stress on the body, which is why we routinely monitor our clients' stress, motivation, hunger and recovery levels. These subjective measures can be indicators of both when we are close to reaching a weight loss plateau and when those adaptive process of the body like reduction in NEAT are kicking in. If the only metric you’re tracking in your weight loss progress is the number on the scale you’re setting yourself up for failure. In order to prevent plateaus due to metabolic adaptation we can give our bodies a period of extra energy that in effect tells it “Ok cool, everything is copacetic. No need to get alarmed and make big changes to NEAT and hormone levels”. This can look a lot of different ways, but for most people it’s a period of 2-3 days of eating at your TDEE calories. Funny enough, since we work with regular people with social lives, families, holidays, vacations and regular weekend shenanigans, these periods of eating at or above their TDEE tend to happen naturally as part of regular life without us instructing them to do so. However, if you’ve been extremely consistent in your caloric deficit and notice your mood, energy and recovery taking a nose-dive, it might be time for a short break from that deficit.
In the longer term, setting a realistic goal as far as how long you’re giving yourself to lose weight is the best bet. If you’re looking at long term weight loss 6-24 months, plan to have periods of eating at TDEE mixed in throughout the process. This can be different lengths of time depending on how big your deficit is, how many pounds you’re trying to lose and how your body responds to being short on energy. Just like shorter term “diet breaks”, sometimes these happen as a part of life in the form of week long vacations, extended slip ups or just not being as careful for a week or two. Don’t get too hung up on the details of this. Monitor your biofeedback, or if you’re working with a coach, keep them up to date on how you’re feeling.
If your goal is muscle gain and you’re eating more than your TDEE to do so, you need to use the same process as we just discussed to set up your caloric surplus. We recommend a conservative approach to muscle gain (lean gaining) in order to skew as much of your weight gain toward muscle vs. fat. Aiming for around .5-1% of your body weight gained per week is the sweet spot for most people. If you’re severely under weight and/or don’t mind putting on some fluff you can be more aggressive. So if your TDEE is 2000 Calories per day and your goal is to gain 1lb per week, you need to be eating about 2500 calories per day on average to make that happen. Remember what we said about protein intake in a surplus. It’s important if your goal is to build muscle, and not just gain fat. When you get to your goal weight, you’ll need to reassess where your TDEE is now that you’re heavier before deciding to maintain your existing weight or look at cutting body fat.
I know that we covered a lot of ground in this article. Honestly we could have gone even deeper into the science, citing the most recent research. We have an open door policy. If you ever have a question or need clarification about anything you are free to email us or contact us through social media or the website.
If I had to summarize this whole thing I’d encourage you to take some time to learn about these topics if they interest you or if you’re interested in “dieting” or gaining muscle the “right” way. In the grand scheme of things, hiring a coach like us to help you do it right is also a wise investment in your health and knowledge.
Don’t get in a rush, and don’t look for quick fixes or fads. They can come at a cost (if they work at all) and it’s hard to imagine a scenario where that’s actually worth it.
Thanks for reading. We value each and every one of you.