Let’s have a look on what an ideal portion size should be. The ideal portion of protein for one meal should be 25% of the plate, or the size of the palm of the hand. When it comes to fats and oils, the portion for one meal shouldn’t be more than the size of a fingertip. Grain should be the equivalent of a modest handful, which represent 25% of the plate. Finally fruits and vegetables should fill half of the plate, which represents the size of two fists.
Sources
1 National Institute of Health, United States. 2015.
Read more on the evolution of portion sizes through the years:
Portion, package or tableware size for changing selection and consumption of food, alcohol and tobacco (review)
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD011045.pub2/epdf/abstract