Every time you eat remember what you already ate and drank in the last few days. Why? Unfortunately, weight is a result of an accumulation of calories. Certain foods have a lot of calories and few nutrients. If you can create a weekly balance between "empty" foods and healthy foods, your weight trend will start to change.
Simple like that!
So, it is important to think about your food and your health.
Have a look at these websites with some ideas about keeping record of your diet.
Will Keeping a Food Record Help You Lose Weight?
Keeping Food Diary Helps Lose Weight
Here’s The Best Way To Start A Daily Food Log For Weight Loss