Metabolic equivalent of task, or MET, is kind of like a measurement that tells us how much energy our body uses while doing different activities. Imagine that your body is like a car, and the MET is like the fuel gauge. Just like a car needs fuel to run, our body needs energy to move and do things.
MET is really just a number that tells us how much energy we use when we do something. Walking might use one MET, but running might use eight METs, which means we're using eight times as much energy to run as we are to walk.
Now, let's imagine that we're trying to figure out how much energy we use while doing different activities. Scientists can measure our breathing, heart rate, and how much oxygen we're using to figure out how much energy we're using. They can then compare this energy use to a standard, which is just sitting and doing nothing, and assign it a MET value.
For example, sleeping might be 0.9 METs, meaning we're using just a little bit more energy than when we're sitting and doing nothing. On the other hand, something like cycling really hard might be 16 METs, which means we're using 16 times as much energy as we are when we're sitting and doing nothing!
METs can help us figure out how to be more active and how to take care of our bodies. We can decide what activities we want to do based on how many METs they use, and how much energy we want to use. So the next time someone talks about METs, just remember that it's a way to measure energy use in our bodies, like a fuel gauge in a car.