What calories are and how to use them

It’s the thing inside your food you’ve heard about, but was too afraid to ask. Apparently a celery stick has practically none, and yet an apple has a ton? If you are confused by calories then read on as we answer the question How many calories you should eat, and more.

What Is a Calorie?

First things first, lets understand the basics of calories. A calorie is a unit of energy. In order for our internal machines to run, we need energy to burn – just like a fire. For humans the importance of calories is in our food, and what we are really looking for in foods is the kilocalorie as opposed to actual calories.

Without going too much into the details, a 100 kilocalories is 100,000 calories. Calories are the unit of energy, and when it pertains to food we are interested in the kilocalorie content of a food. This is more often shown on food products as kcal – it will often also show kJ (or kilojoules) which is the amount of energy the food is giving us, but we do not need to worry about this for the purposes of nutrition intake.

Quick recap: a calorie is actually 1/1000 of a kilocalorie (1000 calories = 1 kilocalorie), for nutritional intake we are interested in the amount of kilocalorie/kcal in a food.

For the remainder of this article a kilocalorie will likely be referred to as a calorie. This is common amongst most phrasing for simplicity, whereas the fact is quite different.

Understanding Nutrition Facts on Food

So with some practice we should be able to align ourselves with quickly understanding the important factors on a Nutrition Facts table on any food, and in doing so this can improve our food choices by knowing your caloric contents better.

When looking at the nutrition facts table on food, which is usually on the back of a product or somewhere otherwise not easily noticeable location, we are looking out for two main things. The first is serving size, and the second is energy.

Why do we care about the serving size? Because more often than not, products with high contents of salt, saturated fat, etc will more broadly advertise the nutritional content of smaller portion sizes. Apologies to go off track here, but it is relevant in understanding this fully, check out this food label example – common these days in UK supermarkets.

It is required that this shows on all food products, and that it shows the percentage of your guideline daily amounts of each category. Some foods show colour coding which helps, but not all.

However, the key thing to notice is the first thing on the label which in this example says “1/3 of a pie (oven cooked)”. This may also be called a “serving” and displayed as “per cooked serving” or similar. The size of this serving is entirely decided by the manufacturer, so you might buy a pie but they’re not expecting you to eat all of it – though we all know we’re going to.

So, back to the original nutrition facts image; it shows us that the facts are per a serving size of 100 grams. The product itself might be 300g. Most food products these days will show both the “serving size” nutrition facts as well as the facts of the entire product, this may be a requirement by law to do so but even so they have the recommended serving size in there to confuse people further and to disguise the fact that most foods are high in salt and other bad contents.

If the full product is actually 300g, and we eat the whole product (in most cases this is true), and all we have is the nutrition facts of 100g then we have some calculating to do. One of the many tactics used to confuse the public in what they are consuming.

As stated previously, we are interested in the kcal of the nutrition facts. Notice that the facts show both Kj (or kilojoules) and Kcal (or kilocalories), but for understanding the calories we are consuming we need only worry about kcal. So for the product from our first image, we can work out that if we were to consume the entire product (assuming it is 300g in weight) that we would consume a total of 1412.10 kcal.

Is There Not an Easier Way to Track?

Good question – yes there is. I highly recommend for those who wish to be calorie-aware, to use the app MyFitnessPal. It has a huge library of foods that you can search for to input at your leisure but better yet, it can scan barcodes of your food products making it even more simple.

So How Many Calories Should I Eat?

AKA will you answer the main question already?

Deciding how many calories you should consume each day requires that you clearly define your goals. Whereas knowing how many calories you should consume is easily calculable.

Let’s begin with the basic details of your current body, write down the following:

  • Your gender
  • Your age
  • Your weight (lbs preferably)
  • Your height
  • Your activity level
    • Sedentary: office job/no current exercise
    • Light exercise: exercise 1-2 days a week
    • Moderate exercise: exercise 3-5 days a week
    • Heavy exercise: 6/7 days a week
    • Extreme exercise: 2x a day

For the last multiple choice, you might have difficulty choosing between two. Lets say you go to the gym 3x a week, but other than that you don’t often do other exercise – you might fall somewhere between Light and Moderate exercise.

Depending on what your goal is would possibly change your choice because of the fact that we are going to be working out how many calories per day we should be eating. So in that circumstance if my goal was to lose weight then I would start off in the Light exercise choice. This is because my goal is to lose weight, and the greater option I choose here will mean I would need to consume more calories to fuel more workouts. If I chose too high then I might waste time eating too much and not getting anywhere with my goal of losing weight.

Even so, you should always re-evaluate your calorie consumption at least once a month dependant on your progress.

Calculate the Calories

With the details from above we are going to work out something known as your TDEE. This is short for your Total Daily Energy Expenditure. With just the details we have written down we can use an online calculator, which are based off scientific principle calculations, to work this out for us.

For beginners I’d recommend the simplistic TDEECalculator.net – as this is no frills clear concise explanation to TDEE.

Head on over to the calculator, and enter your details. For the purposes of demonstrating the details I’ll enter are:

  • Gender: Female
  • Age: 29
  • Weight: 140 lbs
  • Height: 5 ft 5 in
  • Activity: Moderate Exercise

Which after submitting presents us with the following results:

  • 2,109 calories per day
  • 14,763 calories per week

From the calculation, our TDEE to maintain weight is 2109 calories per day. Based on the information we entered, this is the amount of calories we would have to consume each day to maintain our current weight.

So it should make clear sense that if we were to go above or below this amount, something would change. The factor that would change is our weight.

How Do I Lose or Gain Weight?

Now that we have calculated our TDEE, we can now align this to our goals. If our goal is to lose weight, then we simply eat below this amount each day. If our goal is to increase our weight, we eat above this amount each day.

This is the most important factor in weight loss or gain, it is actually significantly less of a factor as to what you eat, or even necessarily how much, it’s all about the caloric content of our foods.

This message goes for those who wish to gain muscle mass too, you wont do this by eating in a caloric deficit (meaning eating less than your daily calories, or TDEE). To create muscle your body needs fuel to do so, and it’s already burning a bunch of fuel to keep your body running as normal, so it needs additional fuel to increase size.

When our bodies do not have enough fuel to run as normal, it will start looking to reserves for this fuel. This is why we store fat and is the primary reserve your body will start to take fuel from if it is in a caloric deficit. You also lose some muscle along with this, and even more so if you are low on body fat.

The Right Amounts

The general rule of losing or gaining weight is to off-set your TDEE by 500 kcal. This is generally a very good starting point and equates to the loss or gain of 1lb per week. It may come with some difficulties however such as low energy on a deficit, and/or trouble to consume the amount of calories needed.

You could change the offset to 2-300 calories per day, which may show closer results to loss or gain of 0.5lb per week.

Either way you should monitor your weight to identify whether your plan is working, and adjust accordingly – as said previously; at least once a month.

Is There a Cheat Sheet?

If you are looking to make changes to your body, whether it be lose weight, gain weight, gain muscle, lose fat, whatever – know this: it takes consistency and as they are beginning to say your body is made in the kitchen. But it isn’t necessarily about eating good healthy foods, it’s about the caloric content.

But in any case, here’s your cheat sheet of the main things to remember:

  1. Know how to read calories on foods (and know that calories means kcal, vice versa)
  2. Track your calories (e.g. with MyFitnessPal)
  3. Workout your TDEE to know how many calories you need per day
  4. Align your caloric intake with your goals; eat less calories for weight loss or eat more calories for weight gain
  5. Be consistent, and re-evaluate your calories at least once a month particularly if you have gained or lost weight