*If you have not read part 1, please scroll down and read that first !! It will complete the story. Thanks!
So you now know the logic behind ‘energy balance’ and have read about energy intake. Now comes the fun part – using the energy so there is no excess to be stored in your body as FAT!
Of course, energy expenditure is not all about avoiding weight gain, it is the essence of life! We need it our basic bodily functions to keep us alive, we need it to enable our muscles to stretch and contract, allowing movement, and to power our nervous system (ie. Let our brains work), and many more.
I hear you ask, what controls my energy expenditure?
The answer is , quite a few factors. Such as,
1) Basal metabolic rate (BMR) – I will explain below
2) Physical activity
3) Body size and composition (lean is best!)
4) Dietary-induced thermogenesis – will briefly explain later
* All the above will vary with age, gender, climate, growth, pregnancy, and whether or not the individual is lactating or not.
Let us quickly go through them one by one.
- Basal Metabolic Rate
This can be thought as how quickly a person uses energy to maintain the basic functions of the body. Typically, BMR accounts for 75% of an individual’s energy needs! BMR is measured when a person is in complete rest (ie. lying on the sofa doing nothing). A higher BMR is good if we want to consume more food. The good thing is, the more percentage muscle our bodies are, the higher our BMR. And ladies, fasting (otherwise known as silly diets) can lower your BMR!!
If anyone is interested to know your BMR, you can calculate it using the following formulas :
BMR = 655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 x age in years)
BMR = 66 + (13.7 x weight in kg) + (5 x height in cm) – (6.8 x age in years)
The answer will be in kcal or calories. This means you will need that amount of calories daily to keep you alive without any physical activity.
- Physical activity
This is pretty self explanatory. Physical activity covers basic movements like walking to strenuous activities such as heavy sport. Just as a reference, on average( by a 25 year old man of 65kg), sitting burns 1.4kcal per minute, walking moderately quickly uses 5 kcal per minute, most domestic work 2.5 – 4.9 kcal per minute, jogging and tennis 5.0 – 7.4 kcal per minute and football or running , over 7.5 kcal per minute.
In these times, finding out how many calories you have used up in exercise is generally fairly easy. Most gyms will have equipment that provides that information and runners can get phone apps to track their runs and display the burnt calories! I use the ‘runkeeper’ app on my android phone.
- Body size and composition
Composition refers to the type of body mass, whether it is lean mass or adipose tissue (fats). Generally, aim for a high amount of lean mass.
Literally meaning heat generation. We use this to refer to the activity of our ‘good fat’ that is the brown adipose tissue (BAT). BAT uses energy from our bad fat (white adipose tissue, WAT ) as a source of energy to generate heat for our bodies . This sounds very exciting at first glance, but the modern lifestyle has diluted our abilities to carry out thermogenesis. There are many articles and supplements across the web that claims to promote thermogenesis and thus help us lose weight faster. I do not use them personally but if you have experimented with any, do share and leave me a comment!
Congratulations for getting this far!
By now you should easily decipher that the final part of the equation , that is the change in energy stores is there to balance out the differences between energy intake and energy expenditure. If :
Energy intake more than energy expenditure, change in energy stores is positive. Therefore energy stores increases and there is excess energy to potentially be stored as WAT or fat.
Energy intake less than energy expenditure, change in energy stores is negative. Therefore energy stores decreases as the stores are depleted to make up for the larger use of energy.
In everyday terms, if I am taking in 1500 calories a day, that gives me 10500 calories a week.
If my energy expenditure is 2000 calories a day, I will use 14000 calories a week, that means my change in energy stores is – 3500 calories, that means losing a pound a week. But, if I exercise by running and burn an extra 1800 calories a week, I will get to consume an extra 257 calories a day because sticking to 1500 calories of food a day is quite frankly, HARD WORK for a foodie like me!
I hope this article has shed some light on weight management for you. Now all you need is a pen and paper to work your numbers out! All the best everyone!