You could start at anytime. I think the older somebody gets and the more set they get in their ways the more difficult it is to make changes. And in that situation my recommendation is to have them start journaling how much they eat and get a perspective of where they are and work on one thing at a time. For example if somebody likes to eat McDonalds for lunch, bacon and eggs for breakfast and chicken fried steak for dinner, that's a typical day for them. But instead of saying I need to reinvent this whole thing I would say lets first start on breakfast. Have oatmeal and some fruit and do that five days a week. Have bacon and eggs one day a week. Do that for couple of weeks and start making a habit of that so it's not so overwhelming. Then once they feel comfortable with that move on to the next aspect. And over the course of several months to a year or two the diet has changed. Their taste and eating habits have changed without feeling deprived.
