I come from a culture where the women have absolute control over the kitchen. What you have to do is simply, politely and cheerfully, refuse to eat the food you find unhealthy. Very nicely and cheerfully request what you would rather eat. Eventually you will get it. If your mom protests that the food will go to waste, just be confident that you are not wasting it because you already made a nice polite request for what you wanted, gave her plenty of notice, etc.

If you are a good son in all other respects, clean up after yourself, are polite and obedient to your elders, do your share of the housework, etc., then your mom will fall into line with the food eventually.

your mom will fall into line

All well and good, but what about when you move out?

You are going to move out of your Mum's place at some point.... right?

I think he did...

The point was, best to learn how to cook NOW instead of when you're kicked out and living on your own :)

I know, I get it. But still, I CAN cook, just I'd prefer not to

Then you can't complain at what your mother cooks you if you're unwilling to do it yourself.