Doctors don’t even take but 40 hours of nutrition instruction in medical school. Even some of them aren’t really giving out very good advice.
My opinion is fruit is good food. All fruit. There’s fiber and vitamins and fruit is tasty. People used to live on freshly hunted meat, and whatever fruits and veggies they could grow or gather. My grandparents ate that way: lean proteins, and tons of fresh fruit and veg.
I also believe that any one diet that would restrict any one food group is probably more woo than beneficial. I find it difficult to believe that one cannot eat healthy, fresh, NONPROCESSED foods in moderation, get sufficient exercise, get sufficient and regular sleep, and be unhealthy. What happened to “an apple a day keeps the doctor away”? Apples aren’t healthy anymore? Nonsense! Of course they are! So are bananas – they are rich in potassium, vitamin C, and fiber.
There is no way that a banana could be less healthy than a cupcake.
I firmly believe that people wouldn’t have to eliminate any food or food group from their diets at all if we didn’t eat processed foods. Fruit juice from a can? Pure sugar, and you might as well drink Kool-Aid. But a whole piece of fruit? I don’t see the problem.
Here’s a couple of links to what looks like reasonable and legitimate websites (to me) for doing your own homework on nutrition. I am not sure what trainers at the gym are actually qualified to do, aside from spot you and teach you how to use certain exercise equipment, but they are not nutritionists.
The US Government.
Here’s the Wikipedia page about nutrition.
And here’s Harvard’s site.
And here’s something called “The American Society of Nutrition.”