[cableshaft]

Keto can result in (somewhat) worse performance depending on how professional you're trying to be and what activity you're doing, but most people aren't trying to compete at that level and they can work out while on a keto diet.

Also, some people up their carb intake a little before their workout, so it'll burn off and they'll still be in keto afterwards while not risking performance loss.

Finally, you don't double your protein intake on keto, you replace your carb intake with fat, so you wouldn't be at 2g/kg/day danger levels you're suggesting if you're doing the diet properly.