following on from my weight loss thread called Calorie Burning:
I was given the advice that calorie restriction was the most efficient way to lose weight, as it is much easier to will-power 300kcal away from a diet than it is to run on a treadmill for 1/2hr (both to the same ends, calorie-wise).
My new question is this: I know (or at least ive read) that 3500kcal is a pound in weight. If we neglect what our bodies burn during normal living, if i eat 3500kcal, do i put on a pound? is the human digestive system that efficient that every single joule of energy in food is absorbed and either used or stored? or does it take what it thinks it needs and then leaves some? if so what the calorific value of, ahem, poo.
We’ve done this thread several times, but the answer is of course “no”. The human body does not store excess calories with 100% efficiency. The caloric value of poo is high enough that in some Chinese farms the outhouse feces dumps directly into the pig sty.
As a point of reference caloric restriction by itself is a poor way to lose weight and does not tend to “stick” re long term weight loss. Adding exercise to your weight loss plan will make you feel better physically and will (in moderation) tend to decrease your appetite. Also the routine of an exercise regime tends to reinforce good eating habits and overall health consciousness.
My understanding is (from my reading back when I was a Dieting Maniac) that your body can do three things with the calories you consume, apart from passing them on through without absorption; not every single calorie you consume gets used.
Anyway, the three useful things it can do are: [ol]
[li]store them as fat.[/li][li]use them for energy[/li][li]use them to maintain body temperature[/li][/ol]
“Use them for energy” covers a lot of ground; it’s not just about burning energy while you jog. Your body takes a lot of energy just existing; loads of calories are burned keeping your heart going, keeping your systems functioning, keeping your brain firing, keeping your cells dividing, and so forth. So, you’ll burn calories by merely staying alive.
Because of that and the need to maintain body temperature, there’s not a hard linear relationship between “calories consumed” and “weight added”. In a strict laboratory sense, a pound of body fat may equal 3500 kcal, but that doesn’t mean that the consumption of 3500 kcal will add exactly one pound in body weight.