Yeah the tuna and water diet at 5 days is plenty. Advocates of no carb dieting say that after 3 months your body then changes and prefers fat for energy. I know past greats cut on zero carbs for months. Vince Gironda with his steak and eggs diet would load some carbs up every few days by having one mal of just carbs. I am not going try that 3 months because you can bet it is hell. I like to feel good!! These types of diets are for short term. I would say that 99% of people would go back to carbs. Now just doing lower carbs is very attainable. I can cut up quickly by just staying at 70grams carbs. As I said before the body was desinged to run on glucose...not ketones.
Today a guy named Lyle McDonald writes a lot about the old school diets.
I agree. I've tried Keto, and I just couldn't hang with it. I felt like crap and my performance suffered big time. I also didn't like how flat I looked all the time. However, I can run low carb and feel pretty damn good and cut up quickly, with no loss of performance in the gym. That's become my preferred method of dieting with lowered carbs instead of no carbs.
(PM me for a price list for Biotech Labs and 10% discount)