From personal experience going from skinny enough that people commented on it regularly to normal size:

The insecurity does not go away if you get in shape. You will feel confident a lot of the time and then the slightest emotional breeze will knock over your confidence. “The day you start going to the gym is the day you start being small forever.”

You can work on your body image while your body is still not “ideal”. If you wait til you look good, you’ll be hot but still have body dysmorphia. Love what parts of your body you can love. Appreciate what your body can do. If you can walk up & down the stairs, be happy you can do that. Go to therapy.

1-3 cups of coffee per day. I try to keep it low, with little success.