How many calories should I be eating?
What is a calorie?
The energy we get from food to fuel our body, is measured in calories (kcal) or kilojoules (kJ).
1 calorie (kcal) = 4.18 kilojoules (kJ)
Food and drinks are made up of different amounts of protein, fat, and carbohydrate (and sometimes alcohol).
The amount of each in the food or drink will determine its energy content. You’ll see energy listed on the back of all packaged food products and you’ll also see the ‘energy per serve’ on all of our Fresh Start meals.
Roughly speaking, it goes like this:
- 1 gram of carbohydrate provides 4 calories
- 1 gram of protein provides 4 calories
- 1 gram of fat provides 9 calories
- 1 gram of alcohol provides 7 calories
What affects the amount of food we need?
Everyone's body is unique. The amount of food and number of calories you need depends on many factors, including your:
- Sex
- Age
- Body size
- Whether you’re pregnant or breastfeeding
Other factors impacting your hunger levels and the amount of food your body may need include:
- Activity levels
- Hormonal health
- Health conditions that may affect the way you digest food
- Any medications you’re taking especially those that affect your appetite or metabolism
- Your personal health goals
How many calories do you need?
For a rough estimate of your daily energy requirements you can use this online calculator here.
It estimates your daily kilojoule requirement for good health based on what your body needs for breathing, circulating blood, digesting food and being active. You can convert this to calories by dividing it by 4.18.
If you want to maintain your current weight, use your current (actual) body weight in the calculator. If you are aiming to lose weight, use your ideal body weight in the calculator. This will give you a lower energy requirement and may help you to start losing weight.
Important note: Calculating your daily calorie requirements should only be used as a rough guide and should never replace any advice from your health professional.
Your individual food and calorie needs will differ day to day and week to week, based on many factors. This is completely normal!
If you notice any unplanned or unexplained weight changes (loss or gain) by how your clothes are fitting, it is important to discuss this with your doctor.
Calories and Weight Loss
We can easily become fixated on a specific number of calories or a specific number on the scales. It’s easy to forget that your body will digest and use calories in a way that is completely unique to you and may be affected by many of the factors explained above.
The number you see on the scales is the total of:
- Bones
- Body organs (including your skin)
- Blood
- Muscles, ligaments and tendons
- Fat
Most of these parts of your body weight you can’t change. The two parts of your body that may change throughout life and contribute to either weight loss or weight gain are muscle and fat.
One of the best ways you can improve your health, body composition and support sustainable weight loss is to make small, realistic changes to improve the quality of your diet and lifestyle.
Using a Calorie Counting App
A calorie counting app like My Fitness Pal can help to educate you around the energy density of different foods and how your calories can add up across a day. E.g. many people don’t realise that a large orange juice or a glass of wine (which are easy to drink) are calorie dense and provide minimal nutrition.
However, thinking about food in this way is one dimensional. It can also encourage disordered eating behaviours and obsessive thoughts around food.
You see, choosing to not eat an avocado or a handful or nuts and eating a processed snack bar that is 100 calories in its place because of the energy density doesn’t make sense and only takes calories into consideration.
This is where calorie counting can be more of a hinderance than a helpful tool.
What is the Food Matrix
Food is so much more than the calories and energy it provides.
The number of calories in a food doesn’t tell you anything about the other nutrients present, it’s quality and how good it is for your health, how quickly it gets absorbed, the impact on your blood sugar levels, or how many additives or preservatives it contains.
The structure of the food we eat is known as the ‘food matrix’ and is important because it affects the availability of energy and nutrients released when food is digested in our gut.
Thinking about the food matrix helps to explain why even if two foods have the same calories they may have a very different impact on our body.
A good example is nuts. Nutrition labels suggest that they contain about 170 calories each handful. However, studies have shown that the fibrous cell walls in nuts stop our bodies absorbing up to 26% of the calories and this energy is instead excreted.
This is why it’s important to be thinking about the quality of the food you eat alongside any calories.
How can you use this information in a positive way?
Finding out the calories you need each day can be a helpful starting point on your weight loss journey but it’s important to remember that we are all different and our needs can change.
Once you have calculated the calories you need in a day it’s a good idea to then shift your focus to the quality and quantity of food and drinks you eat across a day and week.
The ideal diet is one where you can get both enjoyment and nourishment from the foods you eat.
Ideally, you want to be mindful and intentional with your eating and to aim for most of your diet to be based around whole foods to give your body all the essentials it needs to keep you feeling energised and at your best!
Want more advice? Reach out to our team of registered dietitians and nutritionists.
*Our experts provide general evidence-based advice to help you learn about food and how it can help to improve your health and wellbeing. Our advice shouldn't replace any personalised advice that you receive from a Dietitian or other qualified health professional responsible for your care.
References: 1. Mandalari, G., et al., The effects of processing and mastication on almond lipid bioaccessibility using novel methods of in vitro digestion modelling and micro-structural analysis. Br J Nutr, 2014. 112(9): p. 1521-9. 2. Ellis, P.R., et al., Role of cell walls in the bioaccessibility of lipids in almond seeds. Am J Clin Nutr, 2004. 80(3): p. 604-13. Novotny, J.A., S.K. Gebauer, and D.J. Baer, Discrepancy between the Atwater factor predicted and empirically measured energy values of almonds in human diets. Am J Clin Nutr, 2012. 96(2): p. 296-301.