Technically, when he was awarded his honorary doctorate from the university where he originally gained a batchelor's in Sports Science, which would include units on nutrition and research skills/methodology/etc.
Can't imagine that the chaotic household he grew up (heroin addict father and mother with mental illness that require hospitalisation) and attending a non-grammar school (in an area with very strong grammars and independent choices) which would have significantly greater numbers of children with poorer behaviour, SEND and lower academic ability was the best start to life, either. But he got the GCSEs, the post 16 qualifications and the degree, nonetheless.
For all the snotty putdowns, he's not unqualified, has achieved significantly even before you take into account things like raising 2 million quid for charity in one go and has the right to an opinion about health, behaviour and fitness as it is his job and has been since he (quite sensibly) decided that a career as a PE teacher wasn't what he wanted - working as a TA tends to do that to people.