Monday, April 19, 2010

How Many Calories Do I Need In A Day?

Following up from last weeks post, I mentioned that just flashing the number 2,400 calories a day for a 30 year old doesn’t mean much. So this week, I decided, to share with you, a method on calculating how many calories you personally need each day. Now the reason I say personally you, is because this is based on you as an individual. So its not just 2,400 calories for you and everyone else who happens to share the same birth year as you.

Now if you surf the net, you will easily find loads of ways or methods to calculate how many calories you need in a day, and I have chosen to share one of it. So the one i am sharing is not the holy bible of calculating your calorie needs per day, just one of the recommended methods of doing so. Where did i get this formula? I got this from the Nutrition Science for Fitness manual and I find it easy to use and pretty straight forward.

So how do you calculate how many calories you need in a day? You can use the simple formula below:

For men:1 x B x 24 x L x A

For women:0.9 x B x 24 x L x A

Now at a glance, the formula might look like a formula for calculating rocket propulsion against vertical air resistance or some other gibberish like that. But it’s actually quite easy once you know what the B, L and A stands for.

B = body weight (in kilograms),
L = lean factor - or how much body fat you have
A = is activity level.

How do you find each of these values?

B = Body weight
B is pretty simple. You just have to stand on a weighing scale and voila, you have your weight. Now if by any chance, you are using an ancient scale which only shows pounds, you can find out your weight in KG by dividing your weight (in pounds) by 10, and then multiplying that number by 4.5.

L = Lean Factor
L is going to be a little tougher to find out. You can get your gym to a do a free check for you. Most gyms are pretty obliging as long as you are nice to the staff. If you are not a gym member, go to any of the big gyms near you, tell them you are thinking of joining and ask them if they can do a Body Fat Percentage test for you - which will subsequently help you to decide if you need to join the gym or not. They will do it for you for free, in hopes of you joining their gym. So this is one way to find out your body fat %. Now once you have done that, you need to use that information to find out your lean factor. To do that, refer to the table below:-

10 to 14% body fat (for men) or 14 to 18% body fat (for women) = 1
14 to 20% body fat (for men) or 18 to 28% body fat (for women) = .95
20 to 28% body fat (for men) or 28 to 38% body fat (for women) = .90
Over 28% body fat (for men) or over 38% body fat (for women) = .85

A = Activity Level
A, Activity Level can be found by referring to the set of descriptions below. You need to find the one that best describes your activity level on a daily basis.

Sitting, reading, talking, playing video games, or surfing the web throughout the day...
Then your activity level multiplier is 1.30

Lots of typing, teaching, lab works, cooking, and some walking throughout the day...
Then your activity level multiplier is 1.55

Dancing, jogging or lots of walking, tennis, landscaping, OR weight training 1 to 2 hours a day...
Then your activity level multiplier is 1.65

Heavy manual labor like digging, construction or military work along with rock climbing, cycling, OR weight training 2 to 4 hours a day (split into 2 or more workouts of course)...
Then your activity level multiplier is 1.80

Heavy manual labor for 8 hours a day, plus 2 to 4 hours of weight training (or if your name starts with "super" and ends with "man"...)
Then your activity level multiplier is 2.00

OK, now its time to put all that information together and make sense of it.

For example, let’s take a 170 pound man who has 15% body fat and who does very little each day.

Change the pounds to kgs. 170 / 10 = 17 x 4.5 = 76.5 kg.

1 x 76.5kg x 24 x 0.95 x 1.30 = 2267 calories needed each day to maintain his body weight exactly as it is. To gain muscle, he should consume 500 calories more than that. To lose fat, he should consume 500 calories less than that.

So, to lose fat...
2267 - 500 = 1767 calories per day.

To gain muscle...
2267 + 500 = 2767 calories per day.

Now to gain muscle (and not fat), he will need to do weight training as well, and not merely consume 500 calories more a day. If he does not do any exercise and consumes 500 additional calories a day, those calories will get stored away as fat. Again, the 500 additional calories is just a recommendation and will vary from individual to individual.

So now you can pluck in the numbers that are unique to you as an individual and find out how many calories you need in a day and what you need to do to lose fat. So try it out and see. Once you know how much calories you need in a day, you can start deducing a plan to lose weight or gain muscle. In short, this gives you a target or goal to reach, rather than just shooting blindly in the dark. Hope this information is useful to all of you and as usual, look forward to hearing your comments.


mata coklatbiru said...

thanks for the info rajan..
u know,i began workout a month ago and i wonder that im not lose much weight but, i put on weight indeed.
i asked my trainer and the reason i put on weight because my meals 2 times than my work out...
so, with these kind of informations, it really help me to achieve my goal.. :)

Anonymous said...


A very interesting post indeed.

Might it be possible to provide the name of the method/formula? (e.g. Harris-Benedict, Katch-McArdle, etc...)

This will be very helpful to assist in further research.

An excellent post nonetheless! Thanks in advance.

Rajan said...

mata coklat biru: Firstly, thats an interesting name... really.

But i am glad this post helps. Now you can monitor yourself and lose weight continuously. Hope it works.

Anonymous: From my understanding, this formula was created by Dr. Fred Hatfield, who is famous for his website. check it out when you have the chance.

Lexis Excellence said...
This comment has been removed by the author.
Rajan said...

Kasey: Thanks for clarifying and sharing the info. Does this formula have a name by any chance?

Individual Daily Calorie Requirement or something like that?

anfield devotee said...

Eh macha . . . yer blog is becoming a real killjoy y'know . . .

Try calculating how many beers yer allowed at one sitting?

0.5 glass??!!??

Really sucking the joy outta life la ye . . . (*cracks open ANOTHER beer in DEFIANCE*)

Lexis Excellence said...
This comment has been removed by the author.
Rajan said...

AD: 1 beer has about 150 calories. So now you can calculate how much beer you can drink per day. No other blog will share useful info like this with you...Now who says my blog is boring. hehehehehee

Kasey Brown Fitness said...
This comment has been removed by the author.
guntherfurlong said...

Hey rajan...

Is there any ways to calculate the Lean Factor from home? :) or an approximate way? :)

Anonymous said...


Thanks for answering about the name of the formula.

However, I'm unable to find any reference to the formula you posted.

It could just be my own fault for not searching hard enough. Could you point me in the right direction?


Lexis Excellence said...
This comment has been removed by the author.
Rajan said...

Dr. Gunther: The other alternative is to use calipers to measure your body fat %.

When i meet you next, i can take the measurements for you.

sw.yin said...

So, does that mean that if my aim is to gain mass, I should not each more calories than what I needed if I do not do any weight training?

Rajan said...

Swyin: if you eat the same amount of calories, you will maintain your current body weight and not gain muscle mass. To gain muscle mass, you have to do weight training.