Here is the honest truth. There are three states that your body can be in with regard to it's muscle mass:
A. losing muscle
B. maintaining muscle
C. gaining muscle
I'm sorry to say there is no such thing as 'toning' up. You may appear more 'toned' because
1) you are either gaining muscle or
2) you are losing body fat so the muscle you have is more visible.
When we are losing fat we are generally floating somewhere between A and B. If our nutrition and training is on point then we minimise A as much as possible and hopefully hang around B for as much of the time as possible. We cannot lose weight and hang around on C. It's pretty near impossible to manage.
So if we want to be at C then what do we need to do? We need to create a hospitable environment to get some gains! This means:
1) stimulating the muscle growing process via resistance training,
2) creating a calorie surplus and
3) eating plenty of protein.
This does mean that if you are very slim you will need to eat a damn sight more food and lift regularly. And consistently. For a long time...... possibly years to see the results that you want. Sorry to be the bearer of bad news but it's true. You are manipulating the body you have inherited, to become stronger and more muscular by creating the environment that it needs to hit the top of it's game.
For most people the goal is to lose weight and building muscle requires A LOT of stimulation via resistance training, so I won't harp on about this section for too long at this point. I just know a lot of people that lift a lot and regularly but don't manipulate their nutrition to increase their muscle mass..... it can be hard to get your head around adding additional weight to your body, but the truth is that that HAS to happen in order to significantly change your muscle mass. It doesn't mean that you have to put on loads and loads of extra body fat and look like a different person, but it does mean that you are going to have to forego your super lean physique while you put the time and energy into seeing what your body can really achieve.
This is not something that everyone needs to concern themselves with, but I DO want to make sure you guys have all the facts when it comes to body composition!
Anna is a qualified Personal Trainer, experienced Group Exercise instructor and a Master-Trainer for an international fitness brand. Owner of Vital Signz Dance. Creator of Always Moving Forward Instructor Network.