@cornflake
I was wrong when saying a registered nutritionist has to be a doctor, which, obviously is not the case in the US. In my country (Slovenia/Europe), it is not enough to have a degree in chemistry or biology and then (after additional training) you would become a nutritionist within the official medical system; you have to be a doctor.
Here, anyone, who is not a doctor and provides nutritional therapy is in the field of "alternative medicine," which does not include "registered nutritionists." OK, this goes under regional differences the OP asked about.
Ok, I'm speaking only about the U.S. Here, there are registered dietitians, who are licensed, and there's everyone else, who can call themselves nutritionists, nutritional therapists, whatever, and are not licensed or regulated by anyone, certainly including the FDA. None of these people are doctors, or close, except in some rare, random case.
The term "diet" in medicine usually means any eating pattern with a list of foods to eat or avoid. They are many diseases for which specific diets have been
scientifically proven to be effective, for example, gluten-free diet in celiac disease, fructose-free diet in hereditary fructose intolerance, and so on. Or simply, a low-calorie diet to lose weight, which can help to lower cholesterol or improve diabetes 2 or high blood pressure. Scientists, by performing experiments can prove or disprove things, not always, but they often can.
No, these aren't proven. That's not what science does. Low-calorie diets aren't proven to cause weight loss, god knows, weight loss sure as heck isn't proven or even likely to lower cholesterol, as cholesterol isn't particularly likely to be affected by diet, etc., etc. Yes, if you have an allergy, avoiding the allergen is usually a good idea, though not always - there's certainly a body of evidence that leans toward exposure to control, reduce, eliminate allergic reactions.
A doctor can
prescribe a diet, for example a low-phosphorus diet for a kidney patient. Diet can be a therapy, or a preventative measure, so it can be prescribed. There's also a term
"medically prescribed diet."
You asked this about my statement that a registered dietitian is usually not allowed to prescribe diets outside of the current medical doctrine.
When I wrote that, I assumed a registered dietitian would be a doctor. In my country, doctors are officially not allowed to give advice about alternative nutritional therapies and when they do, they may lose their licences. There's one discussion in the news
here, but it's in my language,
Google translate may help (giving nutrition advice outside of official medicine is considered homeopathy here).
A registered dietitian usually needs a licence and I assume he/she can lose it when doing certain things wrong. It is at least this what differs dietitians from self-proclaimed nutritional therapists.
Yes, a registered dietitian can lose their registration or license or whatever it is for whatever kind of thing violates their professional code, though I don't know what that line is. That's it though; there's no law or anything else.
But any diet-related service, even if provided by a "coach" is probably regulated by some law in most countries. In the US, it is US Food and Drug Administration (FDA) that determines, for example, which health claims are allowed on food/remedy products. Also, if a customer considers a certain service a fraud, he/she can sue them. So, I don't think a nutritional therapist is the same as any other random person, when it comes to law.
