That is because dietary advice they give is actually bad. It mostly boils down to "limit calories while eating standard western diet" but that is impossible to follow long-term as SWD and similar (e.g. food pyramid) diets are nutrient-deficient.

How many doctors recommend things like paleo diet, intermittent fasting and so on? Not many, I think - most simply focus on calories, combined with the advice that is either extremely generalized ("avoid sugar") or outright counterproductive ("eat 5 - 6 meals a day"). And then they wonder why people can't follow their diet.

Here I described my own experiences: https://ketoview.wordpress.com/2025/11/09/low-fodmap-keto-di...