I have just started wearing a regular narrow pants belt (not a weightlifting belt) around my midsection approximately at belly button level. I have this over a shirt so it minimizes discomfort, and then optionally wear a sweatshirt over that so it is concealed when I am not home. I have tightened it just enough to force me to hold my abs in, with the rationale that it will at least remind me to tighten my abs and force me to stand/sit straighter. It is a bit uncomfortable but not unbearable and it is not "super tight". I was wondering if this could actually be useful, or if it would just be doing harm.

I have just started wearing a regular narrow pants belt (not a weightlifting belt) around my midsection approximately at belly button level. I have this over a shirt so it minimizes discomfort, and then optionally wear a sweatshirt over that so it is concealed when I am not home. I have tightened it just enough to force me to hold my abs in, with the rationale that it will at least remind me to tighten my abs and force me to stand/sit straighter. It is a bit uncomfortable but not unbearable and it is not "super tight". I was wondering if this could actually be useful, or if it would just be doing harm.

Sounds like a slightly uncomfortable way to work you abs. Adominal defination is achieved by elimating fat and water stores over the muscle, through diet and cardio exercise, weight/resistance training and a healthy protein rich diet. You need to loosen the belt and work out, contracting abs 40-50 reps, leg lifts, crunches, leg flutters, threadmills. Working out 4-5 times a week for 30-60 minutes and a healthy fruit, wheat grains, fruits, low fat, low calorie, low sugar and low fat diet is the only true way to help you abs.:)