Question: Is it a good idea to cook smaller amounts of food so I can't eat larger portions?
Answer: One of the tricks to losing weight is not to cook too much food at the beginning. Portion size is a very important concept. If you cook more food than you should be eating, you will more than likely eat the food. Many studies have shown that people tend to eat whatever is on their plate. Many of us grew up with the 'clean plate club' -- we're supposed to eat all the food so we don't waste any. To only cook the amount of food that you're supposed to eat, so that at the end of the meal all the food that you cooked has been eaten.
You may also want to think about how you put the food on your plate. In general, fruits and vegetables should take up two thirds, at least, of your plate and a higher fat, like meat, should only have one third of the plate.