Where to start with calorie calculators.
Recently I have been getting a lot of messages from people asking how many calories they should be eating, especially now as they are a lot less active during lock down. So, I thought I would try to write a brief explanation of how to work out what you need depending on your goal and lifestyle. Let me start by saying that I am going to try to keep this as simple as possible but some of it does get rather technical.
Now if you Google ‘Calories calculator’ you will get endless results of websites offering calculators to help you workout what calories you need. Whilst this is very helpful you will notice that each website’s calculator gives you a slightly different answer. The reason for this is that there is not one calculation which takes every factor into consideration, it just hasn’t been invented because of the endless possibilities of variables in every human. For example, you could have two males both the same weight, age and height but one of them is only 10% body fat and the other is 25% body fat but when they enter the basic info in most online calculators, they will get the same results. However, most calculators do not consider lean body mass which means the male with 10% body fat will not be eating enough calories to maintain his current weight, as lean body mass burns more calories when resting causing a calorie deficit and possible weight loss.
Even the calculation which most consider to be the best has different versions of it. So while these calculators are helpful its important to keep a track of your own progress and listen to your body and the results. If you follow the calories for a couple of weeks and don’t see the results you want, then adjust it slightly. The calculators are a starting point and not an exact science.
Online calculators work out what your estimated Basal Metabolic Rate (BMR) is then they multiply it by your activity level. BMR refers to the amount of energy (in calories) your body needs to carry out all your essential daily functions like breathing, brain and organ function. The calculation below is a very basic version of the Mifflin-St Jeor equation and is often used to estimate BMR as this equation was found to be the most accurate during studies conducted. After you have calculated your BMR, you will then need to work out any extra calories used for your lifestyle such as exercise and work. Multiplying the two together indicates how many calories are needed to maintain your current weight. I have provided an example below:
Step 1 – Calculate your Basal Metabolic Rate (BMR).
Men BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
Women BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Step 2 – Work out your energy expenditure
1.2 – Sedentary – little or no activity
1.3 – Light – Light activity. Walking, active job or going gym once or twice a week.
1.5 – Moderate – Moderately active. Going gym three or four times a week.
1.7 – Very – Very active. Going to the gym five times a week or more.
Step 3 – Now multiply your activity level by your BMR which will give you a rough guide to how many calories you need to maintain your current weight.
Step 4 – Add or subtract calories depending on your goal. For example, if you want to lose weight aim for less calories. Normally around 500 calories less a day will result in about 1lb of fat loss a week. If you want to gain size, then add calories to this to increase your daily total. Normally around 200-350 would be fine for muscle growth.
Example – Bob is a 34 year old, 193cm tall, 115kg male who is very active and is looking to increase weight.
Step 1 – 2191.25 Kcal a day
Step 2 – 1.7 x 2191.25
Step 3 – = 3725.125 Kcal a day at current activity level.
Step 4 – Increase daily calories to 4025 kcal a day to increase size.
In this example Bob would need an estimated 4025 kcals a day to increase his size. This is due to his activity level and personal goal. So now give it a go and see, then go online and compare results and see what the difference is. The point of this article is to explain how calories are worked out and to show there is no exact way to calculate it. The takeaway is that these calculations are an estimate because no calculation can take in to account every single factor. Use them as a starting point and listen to your body and re-adjust every couple of weeks or so. This is especially important at the moment as it’s harder to exercise as much, so you will be burning less calories.
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