I have not heard of him but I am not a runner.
he's one of the leading proponents of the LCHF diet both for diabetics and non-diabetics, he's a leading sports scientist and physiologist who's getting a lot of flack in South Africa from the dietary establishment for essentially not following scientific procedure and jumping the gun on LCHF. To some extent this is true, in many ways he's doing some of the things that quacks do - going the populist route, but in many ways he's got a lot of evidence, but not the consensus of the scientific/medical/nutrition community who are still sticking the mainstream view of 'balance' between carbs/fats/protein, despite a lot of their 'evidence' being poor quality and/or superceeded.
He's been involved in a disciplinary hearing that's been going on for years now, because (and this of course isn't the whole reason) he advised a woman on Twitter to wean her child onto a low carb diet, pointing out that breastmilk was an LCHF diet in itself.
Frustratingly, proponents of the Low Fat / High carb status quo accuse LCHF advocates of not having enough evidence to change things, and it is true there has not so far been a definitive trial that proves it works and sets some boundaries for it (who and when it's good for the subjects), so this is potentially really exciting.
The real challenge is to design trials when it comes to nutrition - the 'Gold Standard' of scientific trials would be the RCT or Randomised Control Trial - where the patients are divided into groups, typically 2 but sometimes more, and one gets the placebo and other the real thing, without them or the scientists know which is which or they get two different treatments - clearly this is very hard to design, as patients pretty much always know what they're eating. It's also notoriously difficult to get to the truth of what patients are eating and how much exercise they are doing - one solution used by a number of short-term trials has involved locking them into a unit and even into a chamber which accurately measures their calorie output when exercising. This is really accurate in the short term, but wouldn't be feasible in the long term - say over 10 years.
There are so many complications - lifestyle, environment, daily energy expenditure, base metabolic rate, there was even a study showing people with active calf muscles burned more calories when resting, as well as all the 'don't count' calories that we conveniently forget about, there's always some reason why people can choose to ignore the results, or should, but don't.
