Here is another answer without you taking a whole class in biology.
Our body get energy from glucose. Some food allow the release of glucose easier from breaking down of food (fruits) vs some other food that does not like tri-gylerol (fat). The body require more water and time to break those fat into energy that you need when you DO need it to workout. This is partly why eating fatty fast food makes some people slugish.
Another case is eating Candy. Sure you will get energy and calorie from that BUT it is FAST acting so you get a spike in blood sugar level, sugar high. What happens with a high? You will get a low and crash. Additionally, if those energy is not used quickly enough, the body may store it as fat.
Now onto FAST vs SLOW digesting everything (carbs + protein). Not all food are the same, lets take protein. Everyone says to drink whey right after the workout and casein at night. Why is that so? Whey is FAST absorbing to provide quick and immediate aid to the muscle vs Casein is slow digesting for overnight building block.
There are many many more dymanics to food: food pyramid, which diet (percentage of carbs, protein, and fat) is desired for mass gain vs weight loss, vitamens, minerals, etc. If the body is out of balance, you might suffer from disease such as Scarvy (mispell). Some food helps immune system, etc.
Our body get energy from glucose. Some food allow the release of glucose easier from breaking down of food (fruits) vs some other food that does not like tri-gylerol (fat). The body require more water and time to break those fat into energy that you need when you DO need it to workout. This is partly why eating fatty fast food makes some people slugish.
Another case is eating Candy. Sure you will get energy and calorie from that BUT it is FAST acting so you get a spike in blood sugar level, sugar high. What happens with a high? You will get a low and crash. Additionally, if those energy is not used quickly enough, the body may store it as fat.
Now onto FAST vs SLOW digesting everything (carbs + protein). Not all food are the same, lets take protein. Everyone says to drink whey right after the workout and casein at night. Why is that so? Whey is FAST absorbing to provide quick and immediate aid to the muscle vs Casein is slow digesting for overnight building block.
There are many many more dymanics to food: food pyramid, which diet (percentage of carbs, protein, and fat) is desired for mass gain vs weight loss, vitamens, minerals, etc. If the body is out of balance, you might suffer from disease such as Scarvy (mispell). Some food helps immune system, etc.