In the most simplistic form, we can define energy balance as
Energy Balance = Energy In – Energy Out
Energy in is food, since this is the only place that human can absorb energy (calories and joules are both measures of energy). That side of the equation is relatively simple, just add up your total caloric intake. Actually it’s not because the different macronutrients are handled a little bit differently from one another so it’s not simply calories, but that’s another topic for another section. Energy out is the topic of the next several chapters but ultimately represents how many calories you expend in a day.
Long-term changes in energy balance are what ultimately determine what happens to the body.… Keep Reading