The developers behind the app Calorific have measured and then taken photographs of different food stuffs to help show how many calories you are eating without needing to check the label.
Developers argue that the concept of a calorie can be hard to grasp and understanding what foods contain can be even more difficult.
Nic Mulvaney, who has developed the health and fitness app, selected 200 calories because he believes it is a 'nice' portion size.
The app was developed in the UK, for this reason, the names for foods may be different but the amount of calories in different foods remains the same wherever you are.
As these photos show there can be a substantial difference between what 200 calories of say a beef patty looks like versus 200 calories of lettuce.
Here are the photos!