Why Are You Lighter In Space Then On Earth?

In space there is no gravity thus making us lighter

Well it's important to remember that our mass is the same on Earth as it is in outerspace. It's our weight that changes.

Mass is the amount of matter in an object while weight is the effect of gravity on that object, depending on its mass. In outerspace, there's really nothing pulling you down. While your spaceship does have a gravitational pull, gravity is so weak that you won't notice it. You'd be nearly weightless. On a massive body like Earth, the gravitational pull is strong enough that it has very noticeable effects.

A clear example of this aside from outerspace is the fact that you're lighter on the moon than you are on the Earth. Why? Because the Earth has more mass, and thus a stronger gravitational pull, than the moon does.