Back in the 1960's plate sizes used to be 9 inches in diameter. Today plates can be up to 12 inches across. So when we fill our plates with healthy food today, there can be as much as 1100 calories of extra food. Just eating healthy food is not the only thing we need to be doing to improve our health, we also need to trim our waists. Plate sizes really matter, just look at the two plates below. They each have the exact same amount of food on them.