If you have a goal associated with your bodyweight, it’s either to lose, gain or maintain it, right? There are millions of different ways of achieving these goals, but they all revolve around the same scientific principles.



Everyone has uttered the word “calorie”, probably many times. But how many people actually know what it means? (And no, it’s not an elf that climbs into your wardrobe at night to make your clothes smaller!) A calorie is simply the amount of energy needed to raise the temperature of one gram of water in your body by one degree Celsius. How is that information useful? Because the best way to think about food is to consider it as energy (which it is, but you know what I mean). This post is all about energy balance and calories in vs calories out. Essentially that’s what every diet is about.

So now you know what calories really are to your body, in order to figure out how much it needs you have to know how much energy your body expends at rest. This varies from person to person and is otherwise known as your BMR (basal metabolic rate). The higher it is, the more energy you are going to burn. There are all sorts of calculators you can find online to work out your BMR, a couple of examples are here and here. After that, you can use a rough multiplier to take into account the amount of energy you burn in your day-to-day life through walking, talking, breathing, exercising, dancing etc. A couple of websites that do this are here and here. Now you should have a number! That number is more or less how many calories you can consume per day to maintain your bodyweight. Phew, broken a sweat yet?


Surpluses & deficits

If you want to gain weight, you will need to consume more calories (or intake more energy) than your body can burn in a day. That means you’ll need to add to your number of calories to achieve your goal. If your goal is weight loss, you simply need to eat less than your recommended calorie intake. Easier said than done, I know.

One pound of bodyweight is equivalent to 3,500 calories of energy, so if you want to gain a pound per week you’ll need to add 500 calories per day to your calorie number and vice versa. Beware that 500 calories is a lot to add or subtract, so take it slow, start with a few hundred and build up.



Any diet you read about or try is usually an attempt to make it easier to eat a little bit less, or a little bit more than your body needs. For example, cutting out a certain food or food group will probably work if you’re not replacing the calories with other foods. A diet that replaces high calorie foods with low calorie foods will work because that in itself will push you into a calorie deficit (or vice versa for a surplus).


Top tips from the Racefully team:


  • It’s not a race, (but if it were, slow and steady would win it). Don’t cut out or add too much too soon because you won’t be able to maintain it.
  • The best diet is the one that you’re happy following LONG TERM. The best way to find it is through trial and error, but always think of it more as a lifestyle change.
  • If something sounds too good to be true, it probably is. Don’t let yourself be fooled by the “easy routes”. Lots more plants and a lot less junk is generally the way to go.
  • Don’t believe anyone when they tell you that shuffling around what you eat at different times of day alone will enable you to reach your goal – you know the science now. A calorie surplus or deficit is what you need. How you decide to achieve that is up to you. Good luck!


In future blog posts I will go on to talk about good vs. ‘bad’ calories and their effect on body composition as well as performance. I will also write about different types of training and their different impacts on the body. If you have any requests for future posts, please feel free to leave a reply!