I am studying biology at university so i know that the body is an adaptive organism. But, i can say things and say that they are true if there actually are studies (with good studysetup of course)and a body of evidence for it. Your are trying to tell me that if there is a body of evidence showing that IF doesnt boost fat metabolism and is not significantly superior to any other "eating method" (sry i dont know any better word for this, as i am not a native englisch speaker) it doesnt apply to people that didnt participate in the study? so, for you studies dont show anything and are completely useless? I don´t think so.

Therefore these studies will reference internal validity and little external validity.

Maybe after reading your article with references to the things that you are trying to prove and point out, maybe i will change my mind.