How to Calculate Your Calories and Macros

July 18, 2019

What Are Calories & Why Do You Need Them?

Calories are the energy currency your body uses to function. However, not everyone will have the same calories need as the total number you need per day are influenced by a number of factors;

Basal Metabolic Rate: Basal metabolic rate (BMR) is the number of calories you need at rest to allow your body to function at its most basic level. The term, BMR is often used interchangeably with resting metabolic rate (RMR) and makes up the largest part of your daily calorie needs.
The Thermic Effect of Food: In addition to your BMR, there is also the thermic effect of food, which is the technical way of saying, the calories your body uses to digest the food you eat. This process accounts for a small portion of your daily calorie expenditure.
Non-Exercise Activity Thermogenesis (NEAT): Next up is NEAT, which is all the activity you do which is not related to sleeping, eating or exercising and relates to the type of job you work, how much you move during the day, housework and how fidgety you are. (1) It can account for a large amount of additional calorie output daily and explains why some people can eat a lot and still lose weight, but others can’t.
Excess Post-Exercise Oxygen Consumption (EPOC): EPOC, also known as oxygen debt, is the amount of oxygen your body needs after exercise to restore itself to normal resting levels of metabolic function. Its effect is greatest with high-intensity exercise but in general, the overall impact on calorie burn is not significant.
Total Daily Energy Expenditure (TDEE): TDEE for short is the total amount of calories you expend each day, inclusive of the above and any exercise you do i.e. playing sports or resistance training.

As you can see whether you’re at rest, work or play your body is constantly using calories to provide itself with the energy it needs to not only perform but also survive.

Calories are used to keep your heart beating, lungs breathing and brain thinking. Without sufficient calories, your body would cease to function. When you exercise or workout your calorie (or energy) output is increased in order to allow your body to perform the tasks you require of it.

If your calorie input is higher than its output, you will gain weight and if your input is lower than your output you will lose weight. This change in energy is called the energy balance equation.

The energy balance equation, also known as the law of thermodynamics and commonly referred to as calories in vs. calories out and is the relationship between the number of calories we eat and the number of calories we use as energy.

It has 3 outcomes which obey the law of thermodynamics which states that energy cannot be created or destroyed. This means calories must be either used for energy or stored for future use, they can’t and won’t just disappear, (no matter how much we might want them to).

In case you’re wondering ‘calories in’ refers to everything you eat and drink that has calories in it. Whereas, ‘calories out’ is everything you do that uses energy, from simply being alive (heart beating, lungs breathing, digestion) to walking, talking and working out.

The relationship between the input and output of calories dictates whether you gain, lose or maintain weight. For example;

Calories In > Calories Out = Calorie Surplus & Weight Gain – If the number of calories you eat is greater than the amount of energy you use, you will have a surplus of calories and will gain weight.
Calories Out – Calories In = Calorie Balance & Weight Maintenance – If the number of calories you eat is the same as the amount of energy you use, you will achieve calorie balance and maintain your weight.
Calories In < Calories Out = Calorie Deficit & Weight Loss – If the number of calories you eat is less than the amount of energy you use, you will have a deficit of calories and will lose weight.

Day to day you will always be in one of these states, either gaining, maintaining or losing weight.

How Do You Calculate Your Daily Calorie Needs?

Considering all of the above the simplest way to calculate your calories need is to use the following calculations:

Fat Loss = Your bodyweight in lbs x 12
Maintenance = Your bodyweight in lbs x 14
Muscle Building = Your bodyweight in lbs x 16

These calculations will give you a good starting point, but you may find you’re not quite hitting your sweet spot for optimal weight gain or loss.

How Fast Should You Lose or Gain Weight?

Aim to lose weight at a rate of 1 – 2 lbs a week for optimal fat loss and muscle retention and aim to gain weight at a rate of 0.5 – 1 lbs a week for optimal muscle gain and minimal fat gain.

From here you can track your progress by weighing yourself daily and taking a weekly average. If you’re losing weight too quickly, not quickly enough or gaining weight too quickly or not quickly enough then you can either:

Add 100kcals (25g of carbs)
Remove 100kcals (25g of carbs)

Then track your weight again to see if it fixes the problem. Keep using this tactic until you hit your sweet spot.

What Are Macros, Why You Need Them & How to Calculate Them

Macronutrients, also known as macros for short, are the 3 primary sources of calories. Each macro plays a specific role in the body and provides a number of calories per gram;

Protein has 4 calories per gram
Fat has 9 calories per gram
Carbohydrate has 4 calories per gram

Knowing the number of calories provided by each macro allows you to effectively meet your daily calorie needs. To determine how much of each macro you need in your diet you first need to understand the roles they play in your body once they’ve been eaten.

Protein

Protein is important. It’s the building blocks of your body and is responsible for the growth and repair of all cells and tissues in your body and provides your body with essential amino acids it needs to function but cannot produce itself.

In total, there are 20 amino acids, 9 of these amino acids are called essential which means your body cannot produce enough of them and you must get them from food sources. The remaining 11 are called non-essential as the body can produce them in high enough quantities that it’s not essential that you get them in your diet.

Protein is important for its ability to help you build and/or preserve muscle mass, particularly when in a calorie deficit.

You see, protein breaks down muscle through a process called muscle protein breakdown and then rebuilds it through a process called muscle protein synthesis. It’s the trade-off between these 2 processes that will determine whether or not you maintain, lose or in some cases build muscle when losing weight.

Maintaining a sufficient protein intake, not only helps create a positive balance where muscle protein synthesis is greater than muscle protein breakdown, but it also assists with fat loss in another way.

Additionally, protein has been shown to be the most filling macro when compared to both carbs and fat. This means eat a protein-rich diet will not only make you feel fuller for longer but will help keep cravings at bay and make diet adherence much, much easier. (2, 3)

How Much Protein Do You Need?

In the same way, people mistakenly think faster weight loss is better. Most people often think more protein is better. However, this is a mistake as whilst protein is instrumental in helping you maintain muscle mass and feel satisfied after eating, there is a point at which more offers no additional benefit.

In fact, after a point, more protein can be detrimental as it will preventing you from eating a sufficient intake of carbs and fat and maintain a calorie deficit.

For this reason, there is a balance to consider. Eat too much and you don’t leave enough room for the other macros. Eat too little and hunger goes up, muscle mass goes down and things generally get harder and less worth doing. For this reason, you should aim for a protein intake of between 0.8 – 1.1g per lb of body weight. (4, 5, 6)

My recommendation is to aim for the top end of the bracket as much as possible, but if you have days where you’re only getting 0.8 g then don’t worry. The whole point of giving you a range is to allow for flexibility in your diet.

How to Calculate Your Protein Intake

To keep things super simple here I recommend starting out with a protein intake of 1 g per lb of body weight. This means if you weight 150 lbs you’ll want to eat 150 g of protein per day.

Now, remember that protein contains 4 calories per day so to work out how many calories you need from protein daily you simply multiply 150 by 4.
150 x 4 = 600
600 is how many calories you want from protein daily.

Fat

Fat is arguably the second most important macro when it comes to losing fat, due to the role it plays in maintaining hormone levels and providing satiety.

It is vital to maintaining proper function in the body and helps with the uptake of fat-soluble vitamins that your body needs. It’s also a possible source of energy for the body in the absence of carbohydrates.

Fat provides the body with essential fatty acids, which like protein’s essential amino acids cannot be produced by the body and need to be obtained from the diet. Additionally, fat intake has been shown to be correlated with testosterone levels with a lower fat intake leading to decreased testosterone levels. (7)

This important as testosterone plays a vital role in both muscle maintenance and growth and your libido both of which are naturally suppressed when in a calorie deficit. Like protein, fat is also very satiating you and can help control hunger whilst also making food taste good.

How Much Fat Do You Need?

Like with protein, setting your fat intake is all about balance. You want enough fat to sustain health and hormone levels without eating so much (remember it’s 9 calories per gram) that it cuts into your other macro intakes. (8)

With this in mind, you should aim for 20 – 30% of your total calorie intake. This will be enough to get all the benefits of eating fat without going overboard. Again, it’s a bracketed amount to give you some flexibility, if you like to eat more fat then aim for 30% if you prefer to leave more room for carbs then go for 20%.

Ultimately, provided you get at least 0.3 g of fat per lb of fat-free mass you’ll be eating enough to maintain health. (9)

How to Calculate Your Fat Intake

When starting out I recommend aiming for 25% of your daily calories as fat.

Going straight down the middle gives you a nice even place to start from whilst you adjust to your calorie deficit. You can then adjust this and experiment with a higher or lower intake further down the line.

For the purposes of showing you how to calculate it, let’s say your daily calories are 2,000.
To get 20% you do 2,000 x 0.25 = 500.
This means every day you want to get 500 calories from fat.
To get this in grams you divide 500 by 9 which is the number of calories per gram of fat.
500 / 9 = 55 g
55 is how many grams of fat you want daily.

Carbohydrate

Carbs whilst not essential in the same way protein and fats are, are important none the less.

They are your body’s preferred source of energy, increase performance in the gym, aid the function of your brain and assist with digestion.

When eaten carbs are broken down in glycogen which is then stored in your muscles and used as the primary energy source for moderate to intense exercise i.e. weight training. (10)

When compared to low carbohydrate intake (approx. 220 g per day) against a high carbohydrate intake (approx. 350 g per day) the lower intake resulted in more strength lost, slower recovery and lower levels of protein synthesis. (11)

If your aim is to lose fat and preserve muscle mass, you can see why a moderate to high carbohydrate intake is beneficial for you particularly when strength training regularly.

How Many Carbs Do You Need?

This answer is nice and simple. All calories after protein and fat go to carbs. This means once you’ve deducted your protein intake and fat intake from your daily calories the rest goes to carbs.

How to Calculate Your Carbohydrate Intake

Bear with me now, as this looks a little complicated but it’s actually very simple.

Let’s pretend you need to eat 2,000 calories a day to lose weight.
Then let’s say you weigh 160 lbs and are going to eat 1g protein per lb of body weight. This is 160 g of protein daily. If 1 g of protein is 4 calories, we multiply 160 x 4 and get 640 calories of your daily intake is protein.
If you’re then going to use 25% of your daily intake for fat, we know this is 500 calories and because 1 g of fat is 9 calories, we divide 500 / 9 and get 55. This means 500 of your daily calories will be for fat.
If now add your protein and fat calories together 640 + 500 we get 1,140 calories. This is the number of calories that have been allocated to fat and protein.
If we take your daily calories of and deduct what’s been used for fat and carbs 2,000 – 1,140 = 860. This is how many calories you have left for carbs.
We know that 1 g of carbs is 4 calories, so we take 860 and divide it by 4 which gives us 215.
215 is how many grams of carbs you want to eat daily.

Repeat these steps using your own calories, protein, and fat and you’ll be all set.

Are Calories or Macros More Important?

To finish up I thought I’d address the question of which is more important, calories or macros.

Now there’s no arguing that calories and macros are heavily intertwined but a good way to think of the difference is like this;

Calories are the main factor in weight change i.e. will you lose or gain weight
Macros as the main factor in body composition i.e. will you lose fat or muscle or gain fat or muscle

As for what’s more important, it really depends on your goal and what you want to achieve;

Weight change with not too much concern about body composition – if this describes your goal then aim to hit your total calorie goal within 100 kcals either side and you’ll be fine. You’ll change your weight at a steady pace and your daily calories will balance out over the week
Weight change with the primary purpose to improve body composition – if this describes your goal then aim to hit your macros within 5 – 10 g and this by default will keep you close to your calorie goal. Whilst also allowing you the benefits of a well-structured macro breakdown