[5] In the United States, FM practices have been ruled ineligible for course credits by the American Academy of Family Physicians because of concerns they may be harmful.
[8][10] David Gorski has written that FM is not well-defined and performs "expensive and generally unnecessary tests".
[11] Gorski says FM's vagueness is a deliberate tactic that makes functional medicine difficult to challenge.
[1] FM practitioners claim to diagnose and treat conditions that have been found by research studies not to exist, such as adrenal fatigue and numerous imbalances in body chemistry.
[14][15] For instance, contrary to scientific evidence, Joe Pizzorno, a major figure in FM, claimed that 25% of people in the United States have heavy metal poisoning and need to undergo detoxification.