Pretty often I get asked if I have a fast metabolism, and the short answer is not really.
I think a lot of people like hearing ‘fast metabolism’ is the reason why someone looks skinny/fit, and not the fact that they put work in.
Even outside the gym I learned you can build up your metabolism. When I was about 13? I was put on birth control due to PCOS, It caused my childhood-fast-metabolism to immediately slow down and making me gain a lot of weight, pushing me through puberty. I then started getting obsessed with losing weight and training, so on.
Your metabolism outside of fitness can be trained, but it’s all in the matter of your food intake. Small portion sizes, eating slow, and routine snacks/small meals every 2-3 hours to keep your metabolism going. When you keep your portion sizes small your appetite will shrink down with your meal sizes as well. When you eat slow (like we all should) it allows you to feel full, rather than if you just ate super fast you wont feel full because you haven’t given your body time to start digesting and intaking the food you just swallowed. When you go prolonged periods of time without eating, your metabolism slows down because your body thinks it is going to starve, and so it hangs onto what it has rather than burning it away.
Then to maximize metabolic training in the gym, you want to take as little rest periods as possible in between sets. This allows your heart rate to stay high, thus continuously burning calories. When you weight train your body continues to burn calories throughout the day rather than if you just did cardio. The more muscle you build, the more calories you burn at rest.