I am extremely fit. I run miles every week, climb, cycle, lift heavy weights. I eat a very healthy diet, no alcohol, no sugar, vegetarian. I have exercised a lot and eaten healthily for my whole life. I'm a slim size 8. I have excellent muscle definition. I work really hard.
I have an overhang and nothing, but nothing will shift it. There are different types of overhang. Some might be affected by diet and exercise, but others - like mine and I think yours op - are due to the way the incision is stitched and the structure of my abdomen now. It won't reduce. I have a pretty toned stomach down to my belly button. Below it is different.
I've spent quite a lot of time thoroughly miserable about it, but recently have been doing yoga. Does fuck all for the overhang of course, but I'm learning to use my body differently and am actively trying to spend the quieter portion of each practice feeling happy with my body. It is helping. I'm trying to accept it.
A friend chose to save up and had an abdominoplasty. She was the same as me. Incredibly fit (we ran together, did marathon training, hiked), but it just wouldn't go and she decided that surgery was worth it.