Opinion; great, but if you're on it for the right reasons, i.e. it's not for bulking
I've done keto 3 separate times (right now being the 3rd) and yes it worked like I wanted it to all 3 times
No problem with energy
VERY IMPORTANT: keto foods are more filling, you MUST adjust your portion size accordingly. If not you could easily find yourself over eating >>> your body not digesting food >>> holding fat