The only way to know exactly what you are eating, is to weigh your foods and use a nutrition tracker like MyFitnesspal or Cron-o-meter.
This is important to know how many calories you are eating. It is also essential to make sure that you’re getting in enough protein, fiber and micronutrients.
Studies show that people who track their food intake in one way or another tend to be more successful at losing weight and sticking to a healthy diet.
Basically, anything that increases your awareness of what you are eating is likely to help you succeed.