Keeping a food journal has a number of benefits, not least of which is to allow you to take an honest look at what exactly you eat. This may be a real eye opener. For instance, even if you eat healthily for the majority of your meals, you might be surprised at all the extra junk you manage to consume on a daily basis.
Use your food journal to write down absolutely everything you eat, including small snacks, as you go; don't try to remember everything at the end of the day and do it then. Be honest, and don't forget to include any extras, such as sauces, dressings, and toppings.
Specifics you may want to record in your food journal include: