Intro
You probably already know that if you want to manage your weight, you need to manage your calories. But how many calories do you actually need to eat to reach your goals?
There are several factors that go into this, but it’s pretty easy to learn and understand. Once you know how it works, it’s like riding a bike, and you’ll never forget. Almost everyone will have to manage their weight at some point in their life for any number of reasons. Even if you don’t have any fitness goals now, this is good to know. Keep it in your tool belt.
Your body burns calories for energy, and you get those calories from food. So, in order to know how many calories you need to eat, you need to know how many calories you burn.
How many calories do you burn?
Basal Metabolic Rate (BMR)
The majority of the calorie burn will be from something called your basal metabolic rate. It’s also known as base metabolic rate. You may have heard both. This is mostly determined by your biological sex, age, weight, height, and body fat percentage. This makes up most of the calories you burn throughout the day. It accounts for about 60% of TDEE in most people with a normal desk job. 1
Total Daily Energy Expenditure (TDEE)
To get the total calories that we burn in a day, we use our BMR combined with a few other factors. The general formula is:
TDEE = BMR + EAT + NEAT + TEF
Let’s break down some of these acronyms!
Physical Activity
Exercise Activity Thermogenesis (EAT)
This is any form of intentional exercise — running, weightlifting, yoga, a long walk, jumping jacks, etc. As a percentage of the TDEE, this will vary based on the frequency, intensity, and duration of your exercise sessions. If you only hit the gym a few hours a week, it can be as low as 1-2% of your total. If you have frequent, intense, structured sessions it can potentially top out around 30% of your total. 2
Non-exercise Activity Thermogenesis (NEAT)
At a high level, NEAT is basically all other physical activity you do in a day that is not exercise. This includes voluntary activity like walking from room to room, driving, cooking, taking a shower, cleaning, etc. It also includes involuntary activity like fidgeting and posture control. This will vary based on lifestyle. People with active jobs will have a higher percentage of this type of activity.
You can build new habits to naturally increase your NEAT. Here are some examples:
- Park further away so that you get some extra walking in.
- Cook your own meals more often so you are up and moving around and not sitting on the couch waiting for DoorDash.
- Try a standing desk or even a treadmill desk if you’re feeling adventurous.
- Do your own grocery shopping if you’re currently getting delivery (again, more walking).
You can see that the general theme here is “move more, sit around less”. Being more active in ways like this will quickly add up over time and burn many calories. In fact, for people with an active job, NEAT usually burns more calories than their exercise each week. This is true even if they exercise regularly. NEAT can be up to 50% of TDEE. 3
Thermic Effect of Food (TEF)
Your body burns calories during the process of digesting and processing food. This is referred to as the thermic effect of food. Typically, this will account for 10-15% of your TDEE. 4
Here is a breakdown of the TEF of the different macronutrients 5
- Fat 0-3%
- Carbs 5-10%
- Protein 20-30%
This means that for protein, as an example, digesting it can burn up to 30% of the calories it provides. So if you eat a gram of protein that provides you with 4 calories, you may burn 0.8-1.2 calories digesting that gram of protein. Larger meals can also have a higher TEF compared to equivalent multiple smaller meals. 6
This is probably not worth micromanaging, but it is another good reason to focus on protein.
Use a calculator
There is a lot going on here, but luckily, you don’t need to calculate this stuff yourself. If you do a Google search for “TDEE Calculator,” you will find many options. These calculators allow you to input your information to get your TDEE. There are minor differences between them, but I tend to use this TDEE calculator.
Let’s go through the information you will need for the calculator
- Biological Sex (Male or Female)
- Age
- Weight
- Height
- Body Fat Percentage (optional if you happen to know it)
- Activity Level (Be honest with yourself here)
- Sedentary (Office Job)
- Little to no exercise, moderate walking, desk job (at the office)
- Light Exercise (1-2 days/week)
- It could also be light walking 3-4 days/week
- Moderate Exercise (3-5 days/week)
- Physical occupation or sports, construction work
- Heavy Exercise (6-7 days/week)
- Heavy physical occupation or sports almost every day
- Hard labor jobs
- Athlete (2x workouts a day)
- Intended mostly for professional athletes
- Intended mostly for professional athletes
- Sedentary (Office Job)
Consider the result from the calculator as a ballpark estimate. It’s a good place to start out. In your personal TDEE, other factors like medications, genetics, and thyroid activity can make you an outlier. Many more factors can also affect your TDEE. This can cause the calculation to be more inaccurate for you. However, you can still use the result as a starting point without any issues.
What to do with this information
So why do we care about any of these numbers? The short answer is that controlling your calories will directly control your weight. Now let’s get into the long answer and how to implement this control.
Maintenance, Surplus, Deficit
Eating the same number of calories as your TDEE will put you at “maintenance” calories. This means you should not lose or gain weight.
If you eat FEWER calories than your TDEE, then you will be in a calorie “deficit”, and you will lose weight.
If you eat MORE calories than your TDEE, then you will be at a calorie “surplus”, and you will gain weight.
You may also hear this referred to as “calories in, calories out” (CICO). If you know how many calories you burn for your TDEE (the output), then you can control your weight by managing how many calories you eat (the input).
Decide your goal
The next step is to decide what your goal is for your body weight. Everybody has different goals. You may want to gain weight, lose weight, or maintain your current weight.
Once you know your weight goal, then you can define a daily calorie goal for yourself. For the first two to three weeks, eat this calorie goal daily. Use weigh-ins during this time to guide your long-term strategy. The information provided in the rest of this article will help you.
Maintain body weight
If you want to maintain your body weight, eat exactly the same daily calories as your TDEE calculator result.
Gain body weight
If you aim to gain body weight, you should add 500 to your TDEE and use that result as your daily calorie target.
Lose body weight
If you would like to lose body weight, you should subtract 500 from your TDEE. Use that result as your daily calorie target.
3500 calorie rule
A good general rule of thumb for planning is to consider a pound of body weight as worth about 3500 calories. You should know that this rule is not technically correct. There are several more modern, reliable ways to calculate this in a scientific setting.7
However, it is accurate enough to serve as guidance for a starting point, and a starting point is all we really need. 3500 calories divided by 7 days in a week is 500 calories per day. This means if you have a surplus or deficit of 500 calories a day, you should gain or lose roughly one pound a week. Much like the TDEE calculator, this will need to be adjusted for each individual over time. However, it is a good ballpark estimate to get you started.
Adjust over time
Something that frustrates plenty of people when they first get started with a weight management plan is that your TDEE will change as your body weight changes. For example, if your goal is weight loss, then your TDEE will slowly lower as your body weight lowers. That means if you lose 20 pounds (9.07 kg), the daily calorie number you started with will become less effective. You also won’t keep losing a pound per week. You may only lose half a pound per week.
This is normal and expected! You will just need to adjust your daily calorie intake or adjust your activity to account for your new TDEE. You can exercise more to make up the gap. However, in most cases, eating slightly fewer calories is easier. If you are planning a very long weight gain or weight loss phase, you will probably have to make adjustments like this every few months at least. It is a continuous process. Later in this article, I provide some adaptive TDEE strategies to manage this automatically for you.
Avoid extremes
We start with +/- 500 calories a day (+/- 1 pound a week). We do this to avoid any negative side effects of losing or gaining weight too quickly.
If you gain more than about a pound a week, you are usually just going to be gaining extra body fat and not extra muscle. Most males can only hope to gain about 0.5 pounds (0.23 kg) of muscle a week without using steroids. Females can gain up to 0.25 pounds (0.11 kg) per week. Any weight gain beyond this will almost certainly just be body fat. Genetics, age, hormone levels, and many other things can all factor into this potential value.
If you lose more than about a pound a week, you risk losing more muscle mass than necessary. A slow and steady weight loss plan with high protein is a better approach. You’ll retain as much lean muscle mass as possible when you reach your goal weight.
You also want to avoid going below 1500 calories a day if at all possible. Some people may get a value around 1500 from the TDEE calculator. So, even a modest 500 calorie deficit would put them below 1500 calories a day. In these cases, it is better to keep your calories at 1500 and increase your output via exercise like cardio, steps per day, and resistance training. If you go much below 1500 calories a day, you may run into nutrient deficiency issues. You will also struggle with recovering from workouts, and will generally be in a pretty bad mood.
Slow and steady is the way to go for either weight gain or weight loss for several reasons:
- It is more sustainable long-term.
- You can avoid yo-yo’ing your weight or going on an eating spree from being calorie deprived.
- You get a better end result
- When you get to your goal weight, you will have more muscle mass relative to body fat. This will make a large aesthetic difference if you are interested in that.
- Less loose skin
- In the case of weight loss, going slower helps to minimize loose skin if you have a lot of weight to lose.
- Better for your heart
- Extreme rates of weight gain or weight loss can be a risk factor for heart issues. Fluctuating between the two can especially be risky.8
How to adjust for your body
Traps to avoid
Fitness tracker caloric estimates
One of the first things that many people tend to look at in order to estimate their calories burned is the number they see on the cardio machine or on their fitness tracker wearable. Unfortunately, these “calories burned” values are not very accurate at all, even though the heart rate measurements are usually quite accurate.9 For this reason, these readings should not be used for any decisions related to what you are going to eat. At best, you can use them to trend effort between exercise sessions. For example, if you use it to track rowing sessions all month, the “calories burned” value for each session will probably give you a decent trend marker for the level of effort in each workout. But you could just as easily use the average heart rate for this purpose.
Eating back calories
“Eating back” your calories refers to adding extra calories to your day based on your estimate of how many calories you burned while exercising. You should avoid this. Our TDEE calculations already account for the level of exercise. It also makes it harder to adjust caloric goals if it is varying our total calories every day.
Some calorie tracking apps, like MyFitnessPal, will default to adding your exercise calories into your food journal. This encourages you to “eat them back”. This is a setting that can be, and should be, disabled in the app right away.
Adaptive TDEE calculators
To personalize the calculator estimate to yourself, you will need some sort of adaptive calculation. This allows you to find your real-world TDEE over time and stay up to date with how it is changing for your body. This will require you to weigh yourself regularly (ideally daily) and track your calories every day. With that information, an adaptive calculator can identify your personalized real-world TDEE.
If you’re a fan of free things or manual spreadsheets, you can use the nSuns Adaptive TDEE Spreadsheet. Alternatively, there is a nice mobile app called MacroFactor. It combines a calorie tracker with an adaptive TDEE calculator in an intuitive way. It will act as an automated “diet coach” that will continuously tell you exactly how many daily calories to eat to reach your goal at your desired rate. Furthermore, it uses your personal TDEE as a maintenance measure. The app is not free, but does offer a free trial at the time I am writing this.
Adjust based on weigh-ins
Weigh yourself regularly while pursuing a body weight goal. This helps you know when to adjust your calorie intake. For example, let’s say that your goal is to lose a pound a week, but over two or three weeks you only lose half a pound a week. Knowing this allows you to adjust and try lowering your daily calorie intake to get to your desired rate.
For a refinement like this, only make small adjustments. Typically, adjust about 100 daily calories at a time. Avoid reducing daily calories by several hundred at once. Adjust by 100 daily calories, give it a week, check weight again, and re-adjust as necessary.
You also want to make sure to follow some guidelines to ensure accurate weigh-ins:
- Weigh at a consistent time
- First thing in the morning after using the restroom is usually the most reliable over time.
- Weigh daily
- If you can’t do daily, at least try several days a week. Body weight fluctuates a lot throughout the week, so this will help prevent capturing only the extreme fluctuation days.
- Use averages
- Each week, average up all the daily weigh-ins for the week and use this number weekly to track progress.
- Helps to smooth out fluctuations
- If you use an Apple phone, there is a great app to do this automatically called HappyScale.
Conclusion
To recap, the general steps to manage your weight are:
- Decide on your goal — maintaining, losing or gaining weight
- Calculate your initial TDEE estimate
- Calculate your surplus, deficit, or maintenance calorie number
- Eat those calories every day for 2–3 weeks
- Do regular weigh-ins and refer to your weekly average
- If your rate of weight change after 2–3 weeks IS NOT what you expected, then adjust your daily calories by 100 in the appropriate direction depending on your goal.
- If the rate of weight change IS what you expected, then stick to that daily calorie number until the rate of change eventually slows down, after probably a couple of months.
- Rinse and repeat. Adjust your TDEE calculations and calorie intake as necessary. Continue until you reach your goal weight!
Depending on how much you have to gain or lose, this can be a long process. It can be tempting to go to the extremes to speed it up, but that will only set you back in the long run. Stick to the plan, get plenty of sleep, plenty of water, and hit the gym! You’ve got this!
- https://pubmed.ncbi.nlm.nih.gov/15387473/ ↩︎
- https://www.ncbi.nlm.nih.gov/books/NBK279077/ ↩︎
- https://journals.physiology.org/doi/full/10.1152/ajpendo.00562.2003 ↩︎
- https://pubmed.ncbi.nlm.nih.gov/2400767/ ↩︎
- https://pubmed.ncbi.nlm.nih.gov/8878356/ ↩︎
- https://pubmed.ncbi.nlm.nih.gov/31021710/ ↩︎
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3859816/ ↩︎
- https://www.reuters.com/article/us-health-yoyodieting-cardiovascular-idUKKCN1MC2F6/ ↩︎
- https://www.mdpi.com/2075-4426/7/2/3/htm ↩︎
