What's the insanity programme?? Is that P90X? My husband wants to start that, it does look insane.
Do you want to go on an actual diet or just change to a healthier lifestyle? If you have an exercise programme sorted then you can just try to opt for healthier foods. And try some vegetables! Probably the healthiest thing you can do is cook your own food from raw ingredients and don't use too much fat.
Small changes can really make the difference. So don't put extra cheese or cream on everything, watch it with the dressings, they are very high in fat and if you're cooking use olive oil instead of butter. Just be more health conscious about the foods you're eating.
i dunno...mainly, what keeps my weight on track is that, despite BEING american, i hate "american-style" food. fatty, greasy, sugary stuff makes my stomach turn; i've always preferred salads over burgers. so my recommendation is don't go overboard on the american-style stuff. and as for staying on the diet, drink lots of coffee (not decaf). that always helps me.