So, back to the article. Did the guy lose weight and get in shape mainly because of the carnivore diet, or because he started adding intense workouts?
My guess is initially the diet..which as some point levels out. While adding muscle mass ..initially..slowed weight loss..and later speeded up weight loss.
Not a nutritionist..but I believe he will have to stick with a modified diet..maybe walking for as long as he wishes to maintain his overall condition.
Or, he might end up in the worse shape then when he started.