The Essential Guide to Energy Balance and TDEE

Energy Balance: The Core Scientific Principle of Weight Loss and Gain

Here’s the regular dieting pattern – pick up a new diet based on seeing someone’s grand success with it, learn all about he rules of this new way of eating, drop a few pounds pretty quickly and then BAM! You hit the wall and you stop losing weight despite the fact that you’re “doing everything right.”

Sound familiar?

Here’s a fun fact: Every single mainstream diet has the potential to be successful, but most don’t because they attribute the cause of weight loss to the wrong things. Most commonly, there is the belief that there is a master list of foods that will put people into their ideal physiques by virtue of unlocking the true potential of the user. Example lists include: Anything without sugar, anything that doesn’t come from an animal, only foods that were available to our cavemen ancestors, and the list goes on and on. Believe it or not, it’s entirely possible to not only lose weight following these diets to the letter, but it’s also possible to pack on pounds of fat perfectly following them too. That’s because the ‘rules’ of these diets aren’t directly connected to the principle of energy balance, and Energy Balance is the core scientific principle of weight loss and weight gain.

Energy Balance Bullet Points

TDEE: Amount of Calories you use in a day.

Calculate your TDEE at

Consume less calories than your TDEE = Weight Loss.

Consume more calories than your TDEE = Weight Gain.

What is Energy Balance?

The term Energy Balance refers to the relationship of energy you have consumed”versus energy you have used. Energy, in this case, is measured in “calories.” Traditionally a calorie is the amount of energy it takes to heat up 1 gram of water by one degree Celsius. When we talk about the calories in food we’re actually referring to a kilocalorie – the amount of energy it takes to raise 1 kilogram of water’s temperature by 1 degree Celsius. But because “kilocalorie” is such a mouthful we tend to just say “calorie” when we talk about the amount of energy in food.

If you were to add up all the calories in the food you ate over the course of the day and add up all the calories you burned and compared to the two numbers your answer would be indicative of one of three possible situations. The first, is that you have eaten more calories than you have burned. This means that you have excess energy which the body will store for later use. The second, is that you have eaten less calories than you have burned. In this instance, your body will make up the difference by pulling energy from it’s energy storage. Lastly, you may have eaten just as many calories as you have burned. In this case, your bodies energy needs are perfectly in balance with your energy intake. This balance point is commonly referred to as “Total Daily Energy Expenditure.”

This principle isn’t just another dieting idea that works for some people. The principle of energy balance is rooted in the First Law of Thermodynamics. Research has shown that leveraging energy balance by decreasing caloric intake and increasing energy expenditure is effective in improving body composition, even if you don’t exercise, and when paired with a high protein intake much of the weight lost is fat and muscle is preserved. This is only a small snippet of the wealth of research that actively demonstrates that energy balance is the core principle driving changes in body weight. Despite the mountain of evidence, energy balance has it’s detractors and they can even be quite convincing of their point of view.

The most prominent of these views being “If you eat clean, you don’t have to worry about the calories.” This one gets a lot of attention because many people that try it often lose weight successfully, but it’s not because the calories don’t matter. It’s because they have eliminated things like sugary sodas, greasy fast food, and hyper-palatable snack food that are often quite calorie dense while not being filling and replaced them with less energy dense foods like spinach, broccoli, and chicken breast. So yes, you will probably lose weight eating a strictly clean diet but that weight loss is due to an energy deficit – your body does not care if the calories are “clean” or “dirty.”

Another argument that is currently gaining some momentum is that the purpose of gaining fat is to dilute toxins stored in the body and you can only lose fat effectively by detoxing. The sales pitch often goes like this “Have you ever lost weight only to have it come back, and then some? That’s because your body uses body fat as a way to dilute the toxins trapped inside. Our special detox product was specifically formulated by science to cleanse your body of these toxins and flush the fat along with them.” There’s absolutely no scientific evidence for any of these Detox products effectiveness, they’re often just laxatives with some mild stimulants being peddled by snake oil salesmen preying on a very common problem: weight rebound after a diet.

Then there’s the “oh I used to believe in calorie counting and energy balance but it just doesn’t work” person. There’s a handful of reasons counting calories may not have worked for this person; most likely they were not measuring accurately and eating more than they thought they were, having “cheat meals” a little too often, or were wrong about their basic calorie intake needs. People that claim that energy balance is wrong based on their experience were probably not 100% honest with themselves when things got uncomfortable. Saying “weekend calories don’t count” or “I need this extra cake, I did 23 minutes on an elliptical today” or thinking “I can totally eyeball a serving of peanut butter” are just attempts to make ourselves feel better by giving in to what we want right now rather than be a little uncomfortable and work towards that farther off goal.

Lastly, there’s my personal favorite. The “the human body is far more complex than a simple calories in – calories out equation could ever capture.” This an alluring objection to energy balance because it’s built on a small nugget of truth. Yes, measuring calorie intake and burn exactly is impossible with the current tech available today. To make matters worse, our metabolisms aren’t constant – they’re constantly changing based on our current health, how much sleep we’re getting, what we most recently ate – but given all that energy balance still holds true. That’s because none of that actually interferes with energy balance. Calories-in still refers to the amount we consume, regardless of whether or not we know number exactly, and calories-out still refers to the amount we use, even if it changes constantly, and we have an excellent barometer of our energy balance: weight gain/loss.

How to Calculate your TDEE

Total Daily Energy Expenditure (TDEE) is the amount of energy (calories) used in a day through activity and normal body functions. It is the sum of the energy you use over the course of the day as you walk to work, play fetch with your dog, crush it in the gym, Netflix & Chill, everything. Matching the amount of energy consumed to your TDEE is necessary to maintain your current body weight. Because of this you may hear people use the phrase “Maintenance Calories when referring to their TDEE, these terms are synonymous.

TDEE is measured in calories, which makes it a handy tool for dieting. This tool is the “balance” point of the Principle of Energy Balance. When you eat less than your TDEE the “balance” of your body shifts causing a decrease in weight and when you eat more your body weight increases. On a daily basis, this change in weight can be as small as a few grams, but over time these grams add up to pounds or kilograms, making noticeable differences in what we see in the mirror each day.


The upcoming paragraphs explain the math behind calculating your TDEE. You can skip a lot of this and use my free calculator to figure out your TDEE. However, it is extremely useful to understand HOW these calculators work when trying to understand the science of dieting and nutrition.


There are three main components to TDEE – Basal Metabolic Rate (BMR), Exercise Activity Thermogenesis (EAT), and Non-Exercise Activity Thermogenesis (NEAT). The most important of these three is BMR – The amount of energy we would use to keep blood flowing, organs functioning, and our bodies operating; you can think of this as the amount of calories you would need in a coma. In order to calculate an estimate of your TDEE you must calculate your BMR. Typically, a mathematical model is used to determine your BMR and then a multiplier value is used to estimate your activity level. There are three very popular equations/models that people like to use when calculating their BMR. The first equation is the updated Harris-Benedict Equation, which has been the standard for the past few decades but came under criticism in the 90s for consistently overestimating energy expenditure. I still really like this equation for beginners and recommend starting here if you’ve never calculated your BMR before.

Next is the popular Katch-McArdle Equation which takes into account body composition (Body fat %). This may seem small but this is actually really important – two 200lb individuals will have very different BMRs if one of them has 80lbs of fat and the other only has 18lbs of fat. The proportion of lean mass is of critical importance when accurately determining BMR. The glaring issue with this formula is trying to figure out your body fat percentage. There are lots of online calculators, bioimpedance devices at gyms, and other methods but these tend to be very unreliable. Unfortunately, no method for estimating body fat has been shown to be more effective than asking an experienced coach their opinion. Many coaches on social media are more than happy to give you an estimate if you message them and ask nicely.

Don’t worry if these formulas seem intimidating. You can also get a great estimate by multiplying your bodyweight by 10-11; 10 for women, 11 for men (Lyle McDonald; If you’re unsure as to which of these methods gives the best result, the answer is none of them. All of these methods merely give an estimation of what your BMR might be, so take any of these with a grain of salt. Personally, I tend to favor the Katch-McArdle equation for myself and more advanced clients, and the Harris-Benedict Equation for newer trainees. After you’ve calculated your BMR the next step is to estimate the amount of energy you burn through EAT and NEAT.

Exercise Activity Thermogenesis (EAT) – This is the amount of energy used during exercise. Research shows that increasing energy output through exercise is an effective way to achieve a negative energy balance and lose fat. Certain types of exercise can use more energy than others but there is typically a tradeoff. For example, running for an hour may burn more calories in that hour than lifting weights for the same amount of time, however lifting weights will cause muscle damage that will continue to require more energy to repair. That increased energy use will last up to 48 hours after the workout.

Non-Exercise Activity Thermogenesis (NEAT) – This is the amount of energy used during any activity that isn’t “exercise.” This includes walking, taking the stairs, fidgeting at your desk, etc. NEAT is often overlooked but can be a critical source of energy expenditure. When your dieting your body has some natural adaptations that decrease the amount of energy your use through NEAT. This is most noticeable in people that fidget, when you diet long enough you’ll stop feeling the urge to fidget as much as a result of decreased energy intake.

Estimating how much energy we burn through activity is a pretty straightforward process. We use “activity multipliers” to numerically describe how active we typically are in a day and multiply that by our BMR. This has the advantage of being very simple and easy to apply. However, there is the disadvantage of this rating system being very subjective. These are the Katch-McArdle multipliers:

  • 1.2 – Sedentary (Close to no exercise per week)
  • 1.36 – Lightly Active (Lightly Active 1-3 days per week)
  • 1.55 – Moderately Active (Lightly Active 3-5 days per week)
  • 1.72 – Vigorously Active (Very Active 6-7 days per week)
  • 1.9 – Intensely Active (Hard Exercise + Physical Labor 6-7 days per week)

Again, these numbers are not absolute and are somewhat arbitrarily chosen. In reality, you can pick your multiplier from a continuum of any number, typically between 1.0 and 2.0. When you look at it like a gradient it looks like this:

Go with whatever method you prefer to determine your activity multiplier. Once you have it, multiply it by your BMR and voila! you have an estimate of your TDEE. If you went through these paragraphs with a pencil and paper scribbling equations, I applaud you and assume you’re some sort of engineer. If you’re like the majority of the world and don’t want to revisit high school algebra for this then you can calculate your TDEE using my free calculator at

Lastly, we need to figure out just how accurate this number is. This last step isn’t for everyone, if you want to just plug in your numbers into the calculator and use that number – that’s fine. However, for the perfectionists reading this you’re going to need to test this calculated TDEE to see how close it is to the truth. This is a simple process, eat at the level of your TDEE for 7-14 days and record any weight change. If your weight goes up, your TDEE is too high, and if your weight goes down your TDEE is too low. Adjust it accordingly and try again for 7-14 days.

Energy Balance Highlights

Energy Balance is the functional relationship between energy consumed (calories in) and energy expended (calories out).

More energy consumed than expended leads to weight gain.

Less energy consumed than expended leads to weight loss.

The amount of energy expended on a daily basis is called Total Daily Energy Expenditure (TDEE) and it can be estimated using mathematical models. You can calculate your TDEE for free at

Any diet can be successful as long as it adheres to the principle of energy balance. Many diets result in a negative energy balance (weight loss) as a side effect of their main instructions.

Start Here

If you’re completely new to Flexible Dieting then you need to start by applying this chapter. First, calculate your TDEE. Next, download a food diary app and begin tracking your food intake for at least a week at the level of your TDEE. Consider this practice for when you want to get serious about dieting down. You’ll be happy you took the time to practice later on. After at least a week of tracking your food at your TDEE you can adjust your calories up or down to work towards your goal effectively.