• Waite's Warehouse


Updated: Nov 4, 2018

This month’s top tip is by one of our personal trainers, Jonny McCrea and goes in-depth on calorie deficits and how to calculate your perfect calorie intake to maximise your goals.


“Calories in vs calories out” is a phrase most people have heard of, but what exactly does it mean you might ask? Basically, if you burn more calories than you consume you are going to be in a calorie deficit which is what we want if your goal is weight loss or fat loss.

As the diagram above shows you can be in 3 different types of energy balance

  1. Maintenance – The same number of calories going out as coming in resulting in staying the same weight

  2. Deficit – more calories going out than coming in resulting in weight loss

  3. Surplus – More calories coming in than going out resulting in weight gain


How to correctly be in a calorie deficit – How to lose weight correctly:

  • Set target energy (calorie) deficits at the appropriate levels.

  • Do a min of 3-6 hours exercise per week.

  • Use strength/weight training to create muscle damage.

  • Maximise cardio by using High-Intensity Interval Training (HIIT).

  • Use periodic exercise programme changes to compensate for adaptation.

  • Boost non-exercise general physical activity i.e. increase step count, take the stairs!

  • Get quality sleep of 7-9 hours per night.

  • Stay consistent with eating habits.

  • Avoid extreme diets


How to calculate your maintenance level calories – Energy Balance! So now you know the key to losing weight is being in a calorie deficit, but how do you know how many calories your body needs to be in a deficit? Well I am going to show you! Everyone is unique and has their own individual calorie needs. There are multiple formulas for calculating your calories (Katch McArdle, Harris-Benedict) and more. So as an example, I am going to use myself to calculate my daily calorie needs.

Firstly, I will work out my Basal metabolic rate (BMR) which is the total number of calories that your body needs to perform basic, life-sustaining functions. These basic functions include circulation, breathing, cell production, nutrient processing, protein synthesis and ion transport. So, use the formula below to work out your own BMR BMR Formula (Imperial) Women: BMR = 655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years) Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years) Using the formula above my BMR works out at 2182.53 calories. Once you know your BMR, you can calculate your Daily Calorie Needs based on your activity level using the Harris Benedict Equation.


To determine your total daily calorie needs, multiply your BMR by the appropriate activity factor, as follows:

  • If you are sedentary (little or no exercise): Calorie-Calculation = BMR x 1.2

  • If you are lightly active (light exercise/sports 1-3 days/week): Calorie-Calculation = BMR x 1.375

  • If you are moderately active (moderate exercise/sports 3-5 days/week): Calorie-Calculation = BMR x 1.55

  • If you are very active (hard exercise/sports 6-7 days a week): Calorie-Calculation = BMR x1.725

  • If you are extra active (very hard exercise/sports & physical job or 2x training): Calorie-Calculation = BMR x 1.9

So, using the formula of 2182.53 (BMR) x1.725 I would require 3765 calories per day to remain at the same weight. This gives a good starting point to allow monitoring of your daily calories and can be tuned based on performance.


A change in “Energy Balance” is required to create an overall change in body weight and or composition. The body naturally gravitates towards homeostasis where the natural order is maintenance.

One pound of body weight is roughly equivalent to 3500 calories, so eating 500 calories less per week will cause you to lose one pound a week. To lose weight you MUST burn more calories than you consume each day. To affect a gain in lean body mass (muscle) – you need to place yourself into a calorie surplus So, eating 500 calories more per week will cause you to gain one pound a week. To gain weight you MUST consume more calories than you burn each day. So below is a summary of my daily calorie needs if I want to either maintain, gain or lose weight;

  • Weight Maintenance 3765 calories per day

  • Weight Gain of 1lb per week 3765 + 500 = 4265 calories per day

  • Weight Loss of 1lb per week 3765 – 500 = 3265 calories per day

That’s it – it’s as simple as numbers in versus numbers out. Now you know how to work out how many calories you need, keep an eye out for our next article which will give you information on the three important Macronutrients Protein, Carbohydrates and Fats. It’s simple but a helping hand never goes amiss, with the extensive knowledge I can provide nutritional guidance and personal training programmes to line with your goals, get in contact if you want to find out about how my personal training programmes can help you.


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