We’ve said it before and we’ll say it again; Creating a calorie deficit for weight loss is an essential component for success – there’s just no way around it.
This article will explain everything you need to know about a calorie deficit, including what it is, how it plays a crucial role in weight loss and how to achieve it in a healthy yet sustainable way.
A calorie is a unit of energy, most foods and beverages we consume contain calories. Just how many calories are in a meal is a combination of the carbohydrates, fats and proteins it contains.
Creating a calorie deficit is all about calories in vs calories out – when we consume fewer calories than we burn, a calorie deficit is achieved
To create a calorie deficit, we need to find out our Basal Metabolic Rate (BMR) which is the number of calories required to keep our body functioning at rest. We can do this through following the Harris-benedict equation or a myriad of online calculators. BMR is then multiplied by our activity factor to obtain our Total Daily Energy Expenditure (TDEE), TDEE is the number of calories our body burns in a day when daily bodily functions and activity levels are taken into account.
On a side note, the main issue with using a random online calculator is that you’re unsure of what equation/s they’re using to generate your daily calorie allowance (this IS important because all calculation methods are not created equally and there are some that are more accurate than others). We’ve provided the full equations below so you can work it out accurately for yourself.
BMR (Men): (88.4 + 13.4 x weight (kg)) + (4.8 x height (cm)) – (5.68 x age (yrs))
BMR (Women): (447.6 + 9.25 x weight (kg)) + (3.10 x height(cm)) – (4.33 x age (yrs))
BMR is then multiplied by the individuals Activity Factor
Resting BMR x 1.1
Confined to bed BMR x 1.2
Light exercise 1-3 days a week BMR x 1.3
Moderate intensity exercise 3-5 days a week BMR x 1.4 – 1.5
High intensity exercise 6-7 days a week BMR x 1.75
Two a day high intensity workout or physically demanding job BMR x 1.9
If we consume our exact TDEE calorie amount each day, we would neither gain nor lose weight – this is called energy balance or more commonly, maintenance calories. From this point, we can then decide how much of a calorie deficit (how far under our TDEE requirements) we would like to aim for.
The amount of calorie deficit you apply is important because it directly relates to how much restriction is required and therefore your likelihood of being consistent!
E.g. Jill is a 60 year old female who weighs 68kg, is 170cm tall and participates in light exercise up to 3 times per week
Following the equation shown above:
BMR = (447.6 + 9.25 x 68kg) + (3.10 x 170cm) – (4.33 x 60yrs) = 1344
1344 x activity factor of 1.3 – Jill’s daily maintenance calories are 1747.
In the example above, a calorie deficit for Jill is any intake of food during the day that adds up to less than her maintenance calories of 1747Cal. In order to make up the extra calories she needs for the day, her body liberates the energy or fuel from stored fat. Overtime, a regular calorie deficit will continue to require energy from our fat stores to top up our daily energy requirements which means continued conversion of body-fat to useable energy!
Keep in mind that in order to lose 1kg of bodyfat, we need to create a total deficit of around 7,700 Cal. That means that in order to burn a kg of fat in one week, we need to create a deficit of over 1000Cal per day – a tall ask indeed and certainly not something we’re going to be able to consistently achieve for any prolonged period of time.
Ideally we want to aim for smaller weekly weight loss goals – to promote longevity and ensure that we are receiving enough quality nutrition to allow us to continue to effectively participate in work and play.
If we want to lose 0.5kg per week we need to create a 3850-calorie deficit over our 7-day period (550 calorie deficit per day). Food wise, 550 calories is equivalent to 2 donuts from Donut King, a cheeseburger and small pack of chips from McDonalds or 2 slices of pizza from Dominos.
Exercise wise, to burn off 550 calories we need to swim or run for 60 minutes, hike for 120 minutes or mow the lawn for 120 minutes. As you can see, burning what we eat via increased exercise and activity is no easy task. For this reason, a combination of caloric restriction AND increased exercise/activity creates a more manageable approach.
- Portion size. If you reduce your portion size, consider starting with foods that have lesser nutritional value (think junk food) and at main meals try to consume less of the calorie dense foods eg deep fried foods, takeaway and desserts. If we can pay close attention to our portion sizes, we’ll be able to create a calorie deficit that’s efficient for weight loss.
- Be active. The number of calories our body needs is affected by our activity levels as mentioned above with our TDEE. If we have a sedentary job it is important for us to be active so we can consume more food while still being within our calorie deficit. A simple method would be trying to aim for at least 10,000 steps per day
- Drink plenty of water. Ensuring we are consuming at least 2L of water, that’s equivalent to 8 glasses of water. Try to have a water bottle on the go and aim to consume a glass of water before your main meals as this will increase your satiety and help to curb overeating.