Energy Expenditure
By knowing how much weight is being lost and how many calories are being eaten, one can calculate the total amount of energy expended. I also use a website called
PhysicsDiet.com which does this for me. The calculation is straightforward (as long as you understand
units).
My weekly weight loss has been close to 2.4 lbs for the last 3 weeks.
2.4 lbs * 3500 kcal/lbs = 8400 kcal
Now that I know how much I am NOT eating, I can then add that to what I AM eating.
8400 kcal + 9583 kcal = 17983 kcal.
That is how much energy my body has expended over a week. In mathematical terms 17983 kcal/week.
To find out how much I am expended per day
17983 kcal/week * 1 week / 7 days = 2569 kcal/day.
My total energy expenditure is 2569 kcal. There's no need to count exercise and come up with some sort of guess using the Mifflin equation (am I sedentary? am I active?). The information just falls out.
What can be done with this information? Planning can be done. We all know that weight loss is a long term process, and planning is essential to any long term process. Knowing your total energy expenditure will help make plans on how much food to eat in the future and/or if you need to do more exercise.
This number isn't too important to me now, but it will be extremely important when I start my maintenance plan. When I decide to go to maintenance, I need to have a calorie intake that will match my energy expenditure. Knowing this also helps me predict how much weight I will loose when I eat a certain number of calories. While in maintenance, if I notice that I am gaining at a rate of 0.1 lbs a week, I know I need to cut 50 kcals from my diet.
As for now, it is simply fun to know since I am simply setting my calories to 1400-1600 a day. What's interesting is that in the past 3 weeks my energy expenditure has been increasing. The first week of 2.4 lbs/week weight loss I was probably eating too little. When I started to feel listless, I realized that I really should keep my energy intake above 1400 kcal.
I have a few theories on this. My first is that I may be exercising more. I don't believe this is the case, but just like eating without watching my calories, I don't know. My second is the "starvation mode" concept.
This starvation mode is passed on through broscience lessons in weight loss constantly. It usually goes as follows:
If you drop below 1200 kcal/day, you will stop losing weight.This, of course, is not possible. A human body uses energy and without energy intake it will use up stored energy. There is a glimmer of truth to statement. When you are loosing weight, your body will decrease it's energy expenditure. In extreme cases of calorie restriction, one will significantly decrease activity to try to conserve energy. There has been some scientific inquiry into this and starvation mode decreases some weight loss but not all. There is some question as to when it occurs as well. One study has shown that it is linearly dependent on calorie intake. Another shows that it kicks in at an energy intake of 800 kcal/day (very extreme). You can read more about this at the weightwatcher's website:
Starvation Myth