1 - Potatoes were not introduced to the UK until Elizabeth's reign and then would only have been available to the rich.
2 - The Catholic religion of the early Tudors meant that they could not eat meat on a Friday and often not on a Wednesday. On these days fish was eaten instead.
3 - There was no fresh drinking water and so ale was drank with a meal. The very rich may have wine.
4 - Bread was always served with a meal.