Your metabolism describes how your body uses energy to do everything it needs to do to stay alive, and function to keep us healthy. The energy is burned in the form of calories. Your metabolic rate is the rate at which your body burns calories.
You might have heard some people say that they have a "fast metabolism", and they can eat a lot without gaining weight. Someone might also have a slow metabolism, and gain weight easily. This can be the case for different people, but your metabolic rate can change. You can in fact speed up your metabolism with certain types of exercise.
Your metabolic rate actually changes throughout the day, depending on the foods you eat, what time of the day it is and your physical activity. You can even burn more calories for hours after your workout, in a process called “excess post-exercise oxygen consumption”, which can go on usually for up to 13 hours post workout.
EPOC is actually the recovery period that your body has to go through from your muscles being depleted of energy stores and producing waste. This process takes place in two stages, with the most intense phase directly after you're done exercising, with the slower phase lasting up to 13 hours after a good workout.
During this time, more oxygen is needed, as well as calories to get the body back to its resting state. Our bodies are always trying to maintain “homeostasis”, which is the state you are in when you're healthy and at rest. Your body is always doing everything it can to maintain this state – regulating your body temperature, signaling to you when you're tired and need to sleep or rest, signaling to you when you are hungry to fuel your body with food.
You will feel achy after a strength training workout, when energy in your muscles is spent. Cardio workouts are good for strengthening your cardiovascular and respiratory systems, as well as for burning a lot of calories during the workout. Strength training is what will cause EPOC, which is what can raise your metabolic rate for hours after the workout.
During EPOC, your body is hard at work to regulate your breathing and heart rate. It also needs to remove the waste from your muscles produced during your workout, known as lactate and H+, and use oxygen to bring your metabolic rate back to normal, back to homeostasis. The higher amount of calories burned for this process to take place has been referred to as being very helpful to weight loss.
The way you exercise, the duration and different types of exercise you do during your workout can be designed to take full advantage of EPOC. Experts say that if you do some strength training first, and then your round of cardio, you'll end up burning more calories during the cardio portion, as well as continue burning calories after the workout. Even though you can't do the strength training as long, it's actually more effective for weight loss because of EPOC.