Sunday, February 12, 2012

The Science of Weight loss.

Allow me to share with you what I have learned, so far on this journey.  In fact maybe I should have titled this "the mathematics of weightloss" because essentially it's all about the numbers. is that simple!
It's all about Calories in minus Calories out, a deficit results in weight loss, and an excess results in weight gain.
Firstly, you need to calculate your BMR (basal metabolic rate), this is the amount of calories you burn by simply existing. What your body uses to keep you alive, breathing, sleeping, swallowing etc. 
To calculate this, you need to take into account your weight, height, and age. There is a complex formula I could post here for you, but a link to a calculator is much easier.  Find out your BMR here. 
My current BMR is 1640.
If I want to lose weight, I need a caloric deficit.  I am reducing my intake (food) to 1200 calories a day (8400 a week).  I believe this is minimum, any less and your body doesn't get enough and goes into starvation mode, and starts to conserve any fat , preparing for the famine it believes is coming. 
My BMR is 1640 (11480 per week) 
At this stage I am already in deficit, so will lose weight slowly, but to have a more effective result, I need to exercise.  I am aiming to burn an average of 500 calories per day (3500 per week).  I have to add that it is essential to know how many calories you are burning. Guesswork and online calculators can only give you and idea of how many calories you might burn, the only way to really keep track is to use a Heart rate monitor. It is specific for you, set with your height, age and current weight, and can monitor how hard your heart is working and tells you exactly how many calories you are burning. 
This is the HRM I have, and I believe it is the best investment I have made for my health 

So for a week, 
    Calories in (8400) - Calories Out (11480+3500=14900) = - 6500.
Apparently if you have a deficit of 3500 per week, you can expect to lose around 500g that week, 7000 deficit will result in approx 1kg loss. 

Here is an example of what a week's calculations might look like:
If this was my worksheet, I would expect at least a 1kg loss that week.
Simple Maths, right?  That is why it is working. 

So lets look at how I might have been eating before, and look at the Calories in some of those foods that I used to eat regularly.... Now while this is not an example of what I would eat everyday, its not that far off.. especially on a day where I was un-organised, or emotional.

2 slices of Thick Toast, with Butter and Jam = 284 calories
Large Coffee, with full milk and 2 heaped sugars = 262 calories
Large Big Mac Value Meal = 1172 calories
Mars Bar = 251 calories
Smiths Potato Chips (50g bag) = 261 calories
Macaroni Cheese with Bacon (250g serve) = 599 calories

Total piggery for the day 2830 calories!, more than double than what I am eating now, and nowhere near as nutritious.

So if I did no exercise, and had a very sedentary day sitting behind my computer, driving to and from work, taking escalators etc this is how my daily would have looked.

if I ate like that everyday, 1190 x 7 = a weekly caloric excess of 8330,.....  Not really any surprise that I was getting fatter and fatter, is it?

Now lets be realistic, I still like chips and chocolate, but I am learning the cost of what I have to do to burn them off, so they become less inticing.

That packet of chips, has absolutely no nutritional value, so #1 the calories are wasted, and at 261 calories, it takes about 55 mins walking at 5km per hour, to burn that off.

The Big Mac meal could be eliminated by 85mins on a Spin Bike... Stuff That!
So, now you see some of what I have been learning, and with tomorrow being official Day 1 of the 12WBT, lets put all that learning into practise.


Symphony said...

Excellent!! Keep that maths firmly in place in the next 12 weeks (and beyond ...) Best of luck!! Here we go x

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