Weight loss and exercising are counterintuitive

[Scimajor]

My job is as a mathematician and my degree in is Electrical Engineering so things that are counterintuative intrigue me. Before starting my little program of losing weight I ate allot of food (probably averaged more quite a bit more than 3500 calories a day) and exercised less yet I had very little energy. Now that I'm exercising more and eating FAR fewer calories a day I have WAY more energy. As I understand it this is quite common but it makes very little mathematical sense (at least on the surface). 

Don't get me wrong, it's not all happy happy joy joy. I certainly feel hungry almost all the time but I really enjoy having an abuncance of energy. 

[Dominique]

Metabolism is a very complex system: so much so maybe even a matematician can't put it into an equation

On the way exercising affects your metabolism, read the very end of the following blog post by Jeff Galloway:

http://jeffgalloway.typepad.com/jeff_galloways_blog/2012/12/why-diets-dont-work-.html

[Darthlawyer]

I think the problem here is that there are two types of "energy" here that are being used interchangeably, when they aren't.  There is "energy" in terms of total caloric intake and expenditure.  When you diet, you end up with a net loss of calories and burn stored calories in terms of glycogen and fat.  Also, there is "energy" in terms of an increased metabolism or "feeling energetic".  There is a connection in that when you are acting in an energetic manner you are using calories, however, the two aren't dependent on each other.

Basically, when you exercise and eat better, your body becomes more efficient.  This feels good.

[dnourie]

That's because your body was always busy trying to digest. The more food you eat, the more lethargic you are. I was the same way when eating more. I had less energy. At first when I put a calorie limit on myself, I was hungry after exercising. Now I'm not. I'm content on 1200 calories a day, and I have more energy. Food bogs us down, makes us sleepy, because the body is working on digesting heavy meals and snacks.

Enjoyt the adventure!

A side note, I'm 51 and just started learning math two years ago. Hated it when I was younger, but my interest in science and physics ended up making me fascinated about math, and how we use it to describe nature, astronomy, etc. I'm learning precalculus now.