Lobbying.
When the original food pyramid was created, certain groups lobbied the government to have their food categories disproportionally represented. Nutritionists knew that most of your diet should be veggies, but the lobbies that represented farmers (that overwhelmingly grew grains) were able to put pressure on the government to add more grains (same with the dairy lobby).
The more modern “My Plate” is more in line with actual nutritionist recommendations (albeit still problematic with the dairy section).
Latest Answers