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To maintain, lose or gain weight that is optimal to contribute towards your health and well being, it is useful to understand how many calories you need to consume. The body, as a living organism, requires a baseline number of calories in order to maintain regular functions and movement (1). This baseline calorie consumption is referred to as the Basal Metabolic Rate (BMR). It is defined by a calculation used to estimate how many calories are expended by an individual at total rest.
The information required to use this BMR calculator is your age, gender, height and weight. This information is used in the Harris Benedict Equation to calculate your BMR. The Harris Benedict Equation distinguishes between gender and is available to be used in metric (cm and kg) or imperial (ft, inches and lbs) units of measurement. To then understand your Total Daily Calorie Requirement; we need to understand how much physical activity you do on a daily basis in order to account for the amount of calories you burn on average in a day. Firstly we ask for your occupation physical activity level. Those who have active jobs, lifting or on their feet all day, such as labourers, builders and healthcare workers burn on average more calories at work than someone who sits at a desk all day. Secondly we ask how much physical activity you do on a weekly basis to understand how physically active you are outside of your job and daily tasks.
The Reference Daily Allowance (RDA) for calories is recommended at 2500 kcal per day for men and 2,000 kcal per day for women. These are general recommendations and many people will fall below or above these guidelines depending on their individual needs and requirements. This BMR calculator will help you understand how many calories you require to maintain your weight. Of course if your goal is to change your weight by loss or gain you must decrease or increase, respectively, your daily calorie intake.
BMR is the acronym for Basal Metabolic Rate. Basal meaning base, metabolic referring to metabolism and rate; the measure or quantity.
The term refers to the number of calories that you need to consume each day for your body to perform its essential functions such as breathing, eating, digestion, cell production and organ function. BMR is determined using formulas (outlined below) that calculate calories. The calculations can be done manually but using our BMR Calculator is less time consuming and more accessible.
BMR can be used to guide you to the correct amount of daily calories to consume, whatever your goal. It is the starting point of understanding what food and in what quantities you can consume to achieve your goals. There are three main goals associated with calorie intake; weight maintenance, weight loss and weight gain. Weight loss may be sub-categorised into fat loss and muscle gain and weight gain may be otherwise known as muscle gain.
There are many BMR calculations that are used by practitioners and some calculations are more applicable to some populations than others. The following formulas are the Harris Benedict Equation (2). A different equation is applied for men and women to take into consideration physiological differences and is available as either a metric or imperial formula.
Harris Benedict Formula – Imperial
Women: 665 = + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)
Men: 66.5 = + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)
Harris Benedict Formula – Metric
Women: 655.1 + (9.6 x weight in kg) + (1.9 x height in cm) - (4.7 x age in years)
Men: 66.5 + (13.8 x weight in kg) + (5.0 x height in cm) - (6.8 x age in years)
We then ask for your occupation activity level and physical activity level. We find an average of these two and multiple it by the Harris Benedict Equation.
The final result is your Total Daily Calorie Intake.
Once you are equipped with the knowledge of how many calories you need on a daily basis you can begin to plan how you are going to achieve your goal. It is important to set realistic targets and ensure you give yourself time and flexibility to fit your goals into your current routine. Below are some useful tips to help you get started!
Adapting your calorie intake to suit your goals
As previously mentioned depending on your goals you will need to adapt your calories. For weight maintenance it is advised to keep your calorie intake the same. Weight and or fat loss requires a calorie deficit and weight gain requires a calorie surplus. The severity of the deficit will rely on the individual and how suitable it is to their lifestyle. A deficit of up to 500 kcal is advised for weight and fat loss whereas a surplus of 500 kcal or higher will assist with weight gain. Weight change doesn’t happen in a day and it is important to remember that consistency and dedication results in change. Use a Macronutrient Calculator to help you achieve your goals.
Assessing your diet
It goes without saying, understanding what is in your food will assist you with your goals. It can be a mind field and a skill that takes time however understanding food labelling is a great place to start. Keeping a food diary of what you eat can help you identify areas that may be sabotaging your progress. It is useful to be as specific as you can when keeping a diary, weighing your food will help you identify the volume of food and portion sizes suitable for you.
Increase your Physical Activity
Increasing your activity will burn calories. Simple changes such as taking the stairs or getting off the bus one stop early will increase your step count. Aim to walk 10,000 steps a day regardless of your goal. Most smartphones have a built in pedometer for you to track your progress.
Track your progress
Don’t forget to track your progress. As your body changes your calorie requirements will also change. This will avoid a plateau in your progress and keep you on track to your goals.
A BMR Calculator is a great tool to begin your journey but also to track your progress!
1. Fine, E.J. and Feinman, R.D., 2004. Thermodynamics of weight-loss diets. Nutrition & metabolism, 1(1), p.15.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC543577/pdf/1743-7075-1-15.pdf
2.Harris JA, Benedict FG. A biometric study of human basal metabolism. Proc Natl Acad Sci USA 1918;4(12):370-3.