It worked for me. I dropped about 50lbs on a low carb plan. My mom had a summer of parties because she turned 75, and I fell completely off the wagon and gained some back, but it's coming off again as I cut back on the carbs again.
Once you are in Keto, you will have a lot of energy. Your body will basically produce it for you so long as you don't give it any glucose to burn instead.