For anyone who has a goal of wanting to 'lose weight & tone up' -> translated this means to lose fat & build muscle. To have a 'toned' physique it requires having built the muscle (this is where that definition comes from) and lose enough fat to see it underneath.
Muscle building is the key here!
This breaks down how to train in order to build muscle - it's not just lifting ANY weights... but lifting HEAVY relative to YOU.