I challenge the author to load himself on steak and saturated fats and no carbs and come race me 100 miles on a road bike.

I burn in excess of 4000 Calories on a 80 mile bike ride. That's a kilogram of rice on a single ride. And honestly I find it incredibly hard to eat enough just to satisfy the energy requirements of racing. Not eating carbs and attempting an endurance race event is just suicidal and guaranteed way to abandon and not finish at all let alone place well.

Eating large proportion of your energy from meat is also a good way to kill racing performance, let alone if all your energy is from meat.

But even for sedentary lifestyle, no complex carbs at all is sure way to make yourself feel completely miserable. On the other hand living on saturated fat and protein is a sure way to give yourself a coronary disease.