• Science Fueling Fitness

Calories 101


All foods are comprised of calories! The number of calories in each food differs dependent on the type of food, the macronutrients (protein, carbohydrate, fat, fibre) in that food and the quantity of food. Our overall total calorie intake will ultimately be the biggest influence on whether be gain, maintain or lose weight. Calorie ‘maintenance’ is basically the number of calories you need to maintain your body weight – with considerations for daily exercise levels – but essentially if you eat at calorie maintenance, you will maintain the same bodyweight. If you eat in a calorie surplus, you will gain weight. If you eat in a calorie deficit, you will lose weight. It really can be as simple as that. So, how do you determine your individual calorie maintenance, surplus and deficit? Afterall, we all have different caloric needs!


Macronutrients – Protein, Carbohydrate, Fat

There are three main macronutrients – protein, carbohydrate and fat. Each of these differ in their calorie content and so varying amounts of each macronutrient are required. Protein and carbohydrate are low in calorie content, with 1g of either equating to 4kcal, whereas 1g of fat equates to 9kcal!


How to determine your Calorie Maintenance

The most accurate way to determine your calorie maintenance is to track your calorie intake (using an app such as MyFitnessPal is both handy and accurate) whilst also tracking your bodyweight. Bodyweight should ideally be tracked by weighing yourself every morning after you urinate, in as little clothes as possible. Tracking daily bodyweight along with daily calorie intake will allow you to soon realise what your calorie maintenance is. If the scales is staying the same, and calorie intake is the same, then you have found your calorie maintenance. This may take a week or two as establishing a consistent calorie intake can be difficult at first. The impact of exercise can also alter daily body weight, as some intense training sessions require more energy and so on. However, once you have determined your calorie maintenance, it is very easy to then alter your intake to put you in either a calorie deficit (for reducing bodyweight) or a calorie surplus (for increasing bodyweight).


Calorie Deficit (reducing bodyweight)

Once you have established your maintenance calories, all you need to do to create a calorie deficit is reduce your calorie intake by 200kcal. This is a sufficient deficit to get your weight loss started. Reducing too drastically will likely lead to very poor adherence and ultimately a negative association with your nutrition plan. After all, the goal should be to lose weight whilst eating as much food as possible. A simple 200kcal deficit is all that is need. You will need to be consistent and patient with your deficit, but this approach is always better than reducing too much too soon! Learn more about a calorie deficit here!


Calorie Surplus (increasing bodyweight)

Similar to a calorie deficit, when looking to create a surplus, a slight increase of 200kcal is all that is needed to start with. Increasing by too much will likely lead to unwanted fat gain, as an increase in muscle can take significant time – a muscle mass increase of roughly 1kg per month would be considered very good, especially for experienced lifters! Beginners could see progress at a higher rate.



From a caloric perspective, one gram of protein provides 4kcal. From a health perspective, protein is an essential macronutrient and is responsible for muscle retention, muscle growth and muscle function. Therefore, it plays a large role is muscle recovery and a very important role when looking to alter your body composition. Whether you are trying to create a calorie deficit or calorie surplus, protein intake should remain high either way. The standard recommended intake is 2 grams per kg of bodyweight – for example this equates to 150g of protein for an 75kg person. Ideally, your protein intake should be consumed in regular portions of approximately 30g each to stimulate muscle protein synthesis (responsible for muscle growth) as often as possible! Read all about protein in more detail here!



Fat is an essential macronutrient as it is responsible for cell and hormone function. However, fat is the most calorie-dense of all macronutrients, as 1g of fat equates to 9kcal (1g of protein or carbohydrate only equates to 4kcal). There are three different types of fat – saturated, polyunsaturated and monounsaturated fats. Polyunsaturated and monounsaturated fats are the healthier fats to consume, so foods such an oily fish, avocado, nuts and seeds are some of the better options.



Carbohydrates are our energy providing macronutrient. We store carbohydrates in our body in the liver and muscles, in the form of glycogen. The amount of carbohydrates we store in our body can be manipulated to increase the amount of energy we have available to us when we exercise or compete in sporting events. Strategies such as carbohydrate loading aim to increase the amount of energy we have when we exercise, especially exercise of long duration. In fact, carbohydrates should be the macronutrient that varies the most within our diet, with our intake changing based on our exercise schedule (energy expenditure). Many athletes adopt a high-carb/low-carb approach to their training week, which entails a higher carbohydrate intake on training days and a lower carbohydrate intake on non-training days.


Fibre – the forgotten macronutrient?

Fibre is associated with a wide variety of health benefits! There are many forms of fibre, but in short it mainly comes from plant sources and in the form of carbohydrate. There is much debate about its caloric effect, but out of convenience it is probably best to track it as a standard carbohydrate, at 4kcal per gram, although you will probably be overestimating its caloric weight (which isn’t a bad thing). General guidelines are to aim for 10g-15g of fibre for every 1000kcal you consume, or simply approximately 30g fibre each day (as a broad recommendation). In general, consuming a wide variety of fruit and vegetables in your diet is always a good idea and will bring a wide range of health benefits. For tips on how to increase your vegetable intake, you can read more here!


Take Home Messages

· Altering your body composition is largely dependent on your calorie intake.

· Maintenance calories can be determined by monitoring your calorie intake and your morning bodyweight consistently.

· A consistent calorie deficit will result in a decrease in bodyweight. A deficit of 200kcal is a good starting place.

· A consistent calorie surplus will result in an increase in bodyweight. A 200kcal surplus is a good starting place.

· 1g of protein equates to 4kcal. Aiming for 2g protein/kg of bodyweight is a good starting point.

· 1g of carbohydrate equates to 4kcal. Alter your carbohydrate intake based on your exercise schedule.

· 1g of fat equates to 9kcal. Your fat intake should be much lower than protein and carbohydrate, with the majority of your fat intake comprising of polyunsaturated and monounsaturated fats.

· Aim for approximately 30g of fibre each day, or 10g-15g of fibre per every 1000kcal you consume.


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