From his description, my guess is he was not drinking low carb beer. Can we conclude that the best weight loss occurs with moderate/high carbs, no fat and no protein? 
Not sustainable over the long term, of course. But for a crash diet, 44 pounds in 46 days wasn’t all water.
I hope they tell continue to monitor and tell us what happens with his weight loss in the next 46 days.
They won’t, of course. Gaining it all back and then some wouldn’t be sensational news. 
Sounds like a second cousin to the “potato only” diet. McDougall likes to drag that one out and brag on it when he tries to tell us all we should be on starch diets.
I’m sorry but I ENJOY my food! Seriously. I really, really enjoy my food. I enjoy a wide variety of good things to eat. I’ve lost 75 pounds on keto with not a whole lot left to go. I don’t deprive myself. I don’t go hungry.
While these types of stories are amusing, I have no desire to go and do likewise. Kinda have to shake my head and keep on going.
I’m pretty sure that some guys would say that on the beer diet! 
I remember somebody telling me years ago that you could live on just beer for like a year…and then you’d die. 
I did a post here about how he possibly lost weight (44 pounds) drinking beer for 46 days:
When iron rich mitochondrial brown adipose tissue (BAT) is activated (behaves as it were muscle tissue), it browns white adipose tissue and also burns some of it up (hence fat burning) for energy/fuel. When you eat sugar/carbs BAT will burn it directly rather than it being stored as fat.
I wish they would have measured his CO2 (breathing) output with one of those machines Carl & Richard used in one their experiment videos. Because BAT can be activated via the lungs (breathing) through the human spleen (lung spleen axis) along with possibly drinking beer (Iso-α-acids)?
Richard Morris Metabolic Testing at Ketofest Down Under 2018
Dude so drunk all day he wont even notice hes hungry. 
Makes a great story but thats all it really is/can be.
I wonder if the absence of protein and fat (specially protein) paired with low calorie intake crashes the weight even harder via dual catabolism that happens on such low calorie/protein intake with likely no exercise at all due him being drunk all day. 
I imagine catabolism is occurring also, just wish their could have been a team of scientists and doctors studying this guy when he did this! 
No surprise here. Very low calorie, low fat, low protein diet. Of course you lose weight.
Let’s check back with this guy in 2 years and see what that weight loss looks like though
