Let’s be real, calories are the most important thing to track if you’re looking to lose weight or gain muscle. I would even go as far as to say that they’re more important than your training programme. If you want to know why, as well as how to track and optimize your calorie intake to get the results you want, then stick with me for the next few minutes.
What is a calorie?
A calorie is a unit of energy; specifically, a unit of heat energy. Scientifically speaking, it is the energy needed to raise the temperature of 1 gram of water by 1 degree Celsius.
Now, if you really want to impress (or bore) your friends, then here’s a sneaky bit of little-known information. When most people talk about calories in food, they’re referring to “kcal,” and a kcal is 1,000 calories. So when people say they’re eating 2,000 kcal per day, they are technically eating 20,000 calories per day.
However, in this article we’re dealing exclusively with kcal, as that’s what is written on the side of every food packet you’re ever going to read!
Calorie math & key terms
Since the calorie is a measure of energy, it obeys the laws of thermodynamics, including the first – and for us the most important – conservation of energy.
Since your body is an isolated system, this means that you aren’t going to lose weight or gain weight by magic. If you want to lose weight, you have to expend more calories or eat less, and if you want to gain weight, you have to expend fewer calories or eat more.
Here are some key terms to help you out:
- Basal Metabolic Rate (BMR) – the energy in kcal needed to maintain your current size if you are completely sedentary (i.e. you stay in bed all day, every day).
- Physical Activity Level (PAL) – a number that represents how active you are on an average day.
- Total Daily Expenditure (TDE) – your BMR multiplied by your PAL. This is the total number of calories required to maintain your present size as part of your current lifestyle and activity level.
To lose weight and reduce your body fat percentage, you need to consume around 500 kcal per day less than your total daily expenditure (TDE). Over a week, this will usually lead to the loss of between 1 and 2 pounds of fat.
To gain weight and build muscle, you need to eat around 500 kcal per day more than your TDE. Over a week, this will usually lead to a bodyweight increase of about 1%.
Being in a calorie surplus also results in raised testosterone levels, which can help hugely with muscle growth – assuming you’re training enough.
Remember, this process isn’t perfect. It’s hard to know exactly how demanding your training is, and it’s also hard to guess how demanding your work is. Use these figures as an estimate, but don’t be afraid to adjust up or down according to results.
For example, if you’ve been eating what you think is 500 kcal above your TDE, but you haven’t gained any weight in two weeks, then it’s time to increase your calorie intake even more.
Similarly, if you’ve been eating what you think is 500 kcal below your TDE, but you haven’t lost weight in two weeks, then it’s time to reduce your calories further.
How to track your calories
Tracking your calories used to take ages. You’d have to read every packet, write the calories down in a logbook, and add them up each day. Plus, some packets didn’t have calorie labels, so you’d have to make an educated guess.
Luckily, it’s much, much easier to track calories nowadays. There are a whole range of apps that you can download to your phone or use on your desktop. My favorite, and probably the most popular, is MyFitnessPal, which has loads of handy features.
- It includes a database of tens of thousands of foods with nutritional values that you can search.
- It has an awesome barcode scanner, so all you need to do is scan a food packet and it will bring up the information for you.
- Last but not least, the app has a profile memory, so it remembers the foods and meals you commonly eat and keeps them in a list for you to add really quickly.
All this means that it takes no more than five minutes per day to accurately track your calories and your macronutrients.
Personally, I recommend using a three-step process for tracking.
Step 1: Track everything you eat normally for a whole week, without making any changes to your diet. This will give you a baseline number that will probably be somewhere near your TDE.
Step 2: In weeks 2 and 3, either add or subtract 500 kcal per day depending on your goal. Make sure to weigh yourself regularly, and your weight should move in the right direction within two weeks.
Step 3: Adjust your calories over time according to your progress. Your body will adapt and its calorie requirements will change slightly. For example, if you eat more calories and train hard for a few months, you’ll gain muscle. In order to support this new muscle, you’ll need to eat slightly more calories. On the other hand, if eat fewer calories and lose weight for a few months, then your body will very likely need fewer calories to maintain a stable weight.
Final top tip
When tracking your progress, I recommend weighing yourself two or three times per week, in the morning before breakfast each time. This helps to reduce the number of variables.
Wrapping all this up
The internet is filled with so much conflicting information about weight loss and muscle-building, but the number one thing you need to remember is that calories are the biggest factor.
The types of food you eat and when you eat them also play a role, but that role is much smaller. Focus on tracking your calories and measuring your weight – that way you’ll have the best possible chance of seeing the results you want.
How many calories will you need every day?