Hi! Glad you like the game. Unfortunately you can't get rid of most of the flaws (yet). Healthy food is supposed to offset an invisible score that rises when you eat the same food over and over again or when you eat unhealthy food. So in your case it is too late to eat healthy food as you already got the Gluttony flaw.
In the future there will be ways to get rid of it, I just haven't thought of any "fair" system to remove them yet.