This is NOT true!
Each main meal should be complete, that is it must include all nutrients together, so you can combine carbohydrates and proteins, but also fat and fiber.
It is important to have a full meal because:
- It gives our body all the nutrients it needs and in the proper quantities;
- It prevents us from exceeding in a single food amount (for example only a first course or only one second course);
- It helps to reach and maintain satiety longer as complex carbohydrates have a greater satiating power; but the duration of the effect is about 2-3 hours; proteins instead have less satiating power, but the duration of satiety lasts for about 4 hours; fats have a very low but long-lasting (about 7-8 hours) satiating power.
So, we can associate carbohydrates and proteins, but the important thing is to do it in the right doses and following proper nutrition.