Are sit up good for a six pack?

experts say it is totally impossible for you to do this with sit up alone they throw in the answer you must have a low fat low carb low sugar diet with my training answer is yes you can if you do enough 2 or 3 sets of 10 will not work do two or three sets of 25 will not work without a proper diet because it's not enough . none of these experts can show you someone doing 1,000's of setups without having tone and small waist regardless of the diet . you got to remember there's are millions of people with flat stomachs who exercise and don't care anything about a diet . like me i don't have a enough discipline but love the hell out exercising