I agree with leetard except eating less. It is what you eat more than it is how much.
I'm going to list a few things that you have to eliminate from your diet or really try to. But you still need to read the book to fully understand how the body deals with the food you feed it.
Potatoes or potato products
Corn or corn products
Sugar or hidden sugars - read labels
Flour or anything made from i.e., pastas, bread, cookies etc. - Eat whole grain pasta and breads. Read labels and try to buy only whole grain products. If you want crackers buy Triscuits they are made with whole grain wheat..
White rice - Eat brown rice (no instant)
Carrots - in moderation is okay
Any beverages containing sugar - Read labels
Contrary to popular belief, fat does not make us fat. Sugar and refined foods are absorbed into the bloodstream and converted to sugar (glucose) and stored as fat. That is why low fat intake does not work. So you can still have your pasta, bread etc, just buy whole grain. Whole grains are too large to be absorbed into the blood, but their nutrition is absorbed by the intestines therefore they are not stored as fat.
Read labels and try not to buy anything with more than one gram of sugar per serving.
The above is a short list and the worst ones for making and keeping us fat. Drink lots of water, but try not to drink 30 minutes before eating or 30 after as this will interfere with the digestive process.