In the documentary they make mention that the same high carb, low protein/fat diet the government is pushing on people to “get thin” is the exact same diet they give feed animals to “get fat”.
The other interesting thing they note is that when these were being pushed hard the rise of depression books rose a great deal. When you go low on protein and fats, people get depressed. Think about the cult brainwashing diets they put people on, rice, no meats.
It’s a well-established fact of cults to do exactly what you said. The mainstay of the diet given to new members of the Krishna consciousness movement was milk loaded with cane sugar. Coupled with near-endless hours of mindless repetitious chanting and sleep deprivation worked wonders to train or “brainwash” new converts.