ketogenic dieiting has gotten very popular in the mainstream with the whole adkins movement and dave palumbo has gotten a lot of hype in the BB world over the last few years for his keto diet. just like anything, there are pros and cons to it. even dave doesn't put everyone on keto. it all comes down to how you respond to carbs. IME, it works great for athletes that are highly insulin sensitive. i've worked with guys who have to keep their carbs low in the off season or risk getting overly fat. for them, keto is about the only way to get them ripped. for some of them, we go into keto early on in a diet. for many guys, we keep the carbs low and eventually go into keto toward the end. if i can avoid taking someone into keto, i will. when its the only option, we do what we have to do. i would say, of the people i work with, 50% of the men and 80% of women eventually have to go to keto. females have a much harder time losing fat.   

if you're taking the carbs out, the key is making sure that the athlete is getting enough fats.  in case you haven't experienced it for yourself, going into keto can be a very uncomfortable experience. for several days, to a wk, you'l probablyl feel weak, foggy and just plain out of it. at this point, your body is looking for carbs to use as fuel, but it can't find them. eventually, it goes into ketosis and begins using fats as fuel. at this point, your head will begin to clear up and any lost strength will return. you have to be careful with your activity. i wouldn't do any type of HIIT cardio for fear of muscel loss. stick with slow steady state. i do believe that you are more likely to lose muscle of a keto diet than if you are eating carbs. at best, you'll maintain what muscle you have. i am thankful that i can eat carbs on my diets and i find that i'm able to continue to imporve my gains while losing fat, at least for the first half of my diet. you can do keto naturally, but i beleive you will have a better chance of maintaining your size if you are using. 

so in a nutshell, if you dont have to use keto, i would avoid it. if its what you need, then use it. just another tool in the bag. be it, quite a dramatic tool