Even before RFK Jr rubbed his metaphorical nutsack all over our healthcare system, doctors pretty much always told me to eat better. They told me to avoid processed foods, avoid sugar, and focus on fiber and protein.
I don't know why RFK Jr. is getting credit for telling people to eat healthy, especially since some of his recommendations (e.g. telling people to eat french fries if they're fried in beef tallow) are actively bad and will likely lead to people becoming more overweight and less healthy.