I am just going to look here at the very basics of this issue. Different people react in different ways to different stimuli and what makes one person fat may not have the same degree of effect on someone else. Stress, for example, can cause weight gain by slowing our metabolism, altering our blood sugar level and / or increasing our cortisol level which affects our ability to lose weight. But what creates stress for one person may not be the same for another.
So yes, the issue can become a complex one and I am sure an informed reader can raise various points to further complicate the matter.
Why am I Fat?
The most basic consideration is calories in vs calories out. How many calories do you consume on a daily basis compared to how many calories you use in the same period of time?
A calorie is a scientifically created term that allows us to measure how much energy it takes to raise the temperature of 1 gram of water by 1 degree Celcius. In more simple terms, calories in indicates how much energy we draw into our body by eating and drinking while calories out gives us a figure of how much energy we use in our day to day life.
We all use calories to do things as simple as breathe and digest food. Running uses more calories than walking. Athletes use more calories than average as they use more energy. Depending on one’s age, sex, height, weight, level of activity and other factors, we all need a certain number of calories to either gain weight, maintain our weight or lose weight.
So, in theory if a person needs to consume 2000 calories a day (the average for an adult male) and he meets this caloric target, he should neither lose or gain weight if all other factors remain the same. If he raised his caloric consumption to 2500 a day then over a period of time the excess food (represented by excess calories) would be converted into fat and stored as such, causing weight gain and a loss of muscle definition.
On the other hand, if the same man reduces his caloric intake from 2000 to 1500 then in this case he would begin to lose weight as his body begins to burn stored fat (and possibly muscle as well, depending on the actual food consumed).
Here’s the thing though. While you can start with a daily maintenance level of 2000 calories, if you consistently consume say 2500 or 1500 calories a day then given enough time these new levels will become your maintenance levels. Therefore in order to gain or lose weight you will have to make your calculations from your new maintenance level.
This is a basic answer to the question Why Am I Fat?, but also very important to understand. In many cases losing weight (or bulking up to build muscle) may not be any harder than varying your caloric intake. Note though that different foods provide different nutritional values. There may be little to no difference calorie wise between a glass of whole fat milk and a glass of coke but the nutrition provided by both beverages is vastly different.
