Here's the problem: Even that's too much friction. You probably will have a nice base of users that are hardcore dieters, but I don't think you will reach the

Here's the problem: Even that's too much friction. You probably will have a nice base of users that are hardcore dieters, but I don't think you will reach the niche you are targeting. I think the problem lies in the fact that most eating is a social activity and most social places to eat (ie restaurants) aim to make their food tasty instead of healthy. I think movements to make calorie counts on every menu will help much more than to develop an app like the one you proposed.