Do you know how many calories you should consume to maintain your weight? How should it be divided between proteins, fats and carbohydrates? The math is simple and will tell you a lot about your body that you did not know till today. Lets begin:
Calculating Total Calories Consumed Per Day
Your Daily Calorie Requirement = Calories Needed at Rest (BMR) + Calories Required for Activity through the Day +/- Your Metabolic Adjustment
To find out approximately how many calories your body needs at rest, you need to know your body weight and your body fat (%). Here is how you can measure your body fat percentage.
A body fat measuring device is a good investment as you can track your progress easily without bringing out your inch tape all the time. Until you can get your hands on it, you can use this link to enter your body measurements and find out your approximate body fat (%).
Finding the Calories Needed at Rest (BMR):
Using this Katch McArdie formula, you can know how many calories you consume at rest (or your Basal Metabolic Rate i.e. BMR):
BMR = 370 + (21.6 x (W x (1-BF) ) )
where W is your weight in kgs and BF is your Body Fat %
For example, I am 57kgs with 21% Body Fat, then my RMR is 370 + (21.6 x (57 x (1-0.21) ) ) i.e. 1342.6; for simplicity lets say 1350.
OR use this calculator here that takes in your height, weight and gender to give you your BMR calories.
Adjust for your activity levels:
If you are sedentary you multiply your BMR with a factor of 1.2,
if moderately active then with 1.5,
or if you are fairly active then with 2.
You would be moderately active, if you walk around most of the day like a salesman or if you really sweat everyday for about 30 minutes. You will be fairly active if you train like a sportsperson or similar. Most of us are either desk-bound with 2-3 sessions per week in the gym – for the purpose of this calculation then, it is safe to assume yourself to be sedentary.
In which case, your calories consumed through the day will be your BMR x 1.2 (i.e. 1350 x 1.2) ~1620. I have been using a fitbit band for the last few weeks and this is fairly close to my calorie burn through the day except for the days when I go to the gym which adds about 170 more calories. You can read my full review of FitBit here: My experience with FitBit Charge.
The Final Number: Now, at best the number we have calculated is an approximation. You can have faster metabolism than the average or maybe even slower. The only way to find out your exact calorie requirement is to track your weight fluctuation over weeks and matching it up with the calories you are consuming. That or you can undergo magnetic resonance imagery which is used in research labs! For now lets stick to experimentation even though it sounds like a lot of work!
If you want to gain weight then add 200 calories to your calorie requirement calculated above. To lose weight reduce 200 calories from this final number and you will be able to drop about 1/2 pound every week. My target is to gain weight, so my calorie target per day is (1620+200) ~1820 calories.
After doing this, if you find that the weight is not changing, you have to keep adjusting the calories till it does – this is the experimental way of understanding your body’s calorie burn capacity.
From the BMR calculation above, you will notice that the more lean body mass you have (i.e. your Total Body Weight – Your Body Fat Weight), the higher your metabolism! Your lean body mass is the weight of your bones, organs, other tissues and muscles. Muscles consume energy even when at rest. That is why putting on muscles is not easy, your body is resistant to adding an energy drainer in your body. But if you want to kick up your metabolism then putting on muscles is the way to go.
Sorting out the Macronutrients: The Carbohydrates, Fats and Proteins
Now that you know how many calories you can consume given your activity levels, lets explore what it is that you can eat.
Proteins: In our previous article we have discussed in details about how much protein you actually need. Based on my goal to gain weight ( /lean mass), I calculate my protein requirement:
Weight in kgs x Lean Body (%) x Protein Factor
i.e. 57kgs x (1-0.21) x 1.8 = 80g
where Lean Body (%) is simply = 1-BF(%)
For example, in my case, this is 80g of proteins. 1g or protein has 4 calories. So, protein takes up 320 calories in my diet. How many grams is it for you?
Fats: Coming to your fat intake, it can vary from 20% – 35% (Ref1). I would suggest to keep this as close as possible to your actual diet. Log your normal ‘diet’ for a few days into myfitnessPal or any similar app and find out how much fat you consume on a daily basis. If this is more than 35%, it would make sense to rethink the trans fats creeping into your diet. Remove those and see if that brings your fat consumption to under 35%.
While tracking the fat you consume on a daily basis, it can be easy to underestimate this number. This can be especially true in Indian cooking where it can be difficult to exactly measure how much oil you are putting in every time. From logging my diet and watching my cook like a hawk, I know my fat consumption is close to 25%. If you can accurately measure this, then go for it.
Now keeping this constant is good to have continuity in your diet. Since 25% of my calories need to come from fat, lets calculate the gms and calories from fat:
Your Daily Calorie Target x %Calorie Contribution from Fat
i.e. 1820 *0.25
which will give me 455 calories in my diet should come from Fat. 1gm of fat has 9 calories and so this converts to 45g of fat.
Carbohydrates: The remaining calories will come from carbohydrates. To calculate the calories from carbohydrates, you simply do:
Your Daily Calorie Target – Calories from Proteins – Calories from Fat
i.e. 1820 – 320 – 455 which is 1045 calories. Since 1gm of carbohydrate has 4 calories, I should aim for about 260g of carbohydrates.
Any diet will be successful depending on how easily you are able to adopt it into your daily routines. This calorie and macronutrient calculation takes into account your lean body weight and your existing fat intake. In a way it is tailored to fit in with your goals and also be as close to your existing diet as possible. This is therefore a very personalised set of numbers that you can start to play around with.
For my goal to gain weight, we have calculated that by consuming 1820 calories in the ratio of roughly 20:25:55, I should be able to gain lean mass spread over weeks.
Have you completed your calculation also!? By doing this, you have taken the first step in unlocking your body’s diet secrets. From here, you need to track your daily diet to find out how close or far you are from your target numbers.
Continue reading about why Dieting Fails and what you can do about it.
Ref1: National Academies Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fat , Fabre, Fatty Acids, Cholesterol, Proteins and Amino Acids. September 2002.
PS: This site utilises affiliate links to help sustain our efforts in getting you the best information possible and continue sharing genuine product recommendations