Self-deconstructing clichés: Weight-loss edition

Continuing my series on figures of speech being modified to eliminate their actual meaning, we have this comment on the discovery of the “holy grail” of obesity research. The holy grail, as a reminder, was a unique item in Christian mythology, the dish that caught Jesus’ blood, the single holy focus of the quest of King Arthur’s knights. According to legend it had magical healing properties. As for this holy grail,

Tam Fry, of Britain’s National Obesity Forum, said the drug is potentially the “holy grail” of weight-loss medicine… “I think there will be several holy grails, but this is a holy grail and one which has been certainly at the back of the mind of a lot of specialists for a long time.

As for the magical healing,

All of the other things apply – lifestyle change has got to be root and branch part of this.

And then we have to wonder — a self-deconstructing cliché twofer — what does he mean by “root and branch part”?