I was thinking alone these lines yesterday afternoon.
A real low carb diet (less than 50g day) for max of One month
Replaced with a proper spread of carbs/protein/fats for another month or two
Repeat till desired weight is achieved
This being more for Overweight people who are not athletes. Being an athlete and trying to loose fat and train/recover/improve on a very low carb diet just does not happen properly. Even as an athlete, drop the fat Before you need to be preparing to race well. That gives you time to improve - as your eating correctly to allow adaptation. As for only 3days on low carbs - its been shown that Ketosis really does not kick in till 48hrs, then fat starts to burn. That leaves 1 day of fat burning then your adding in carbs again? If your going to put your body into Ketosis, get it there, and keep it there. 20-50g day of carbs at max. (remember body cant digest fiber, so eat plenty of salad/vegies.) If you only need to loose a few kg, then a week or two should be all you need. You will have to stop all high intensity efforts in that time, but hey, its only a short period of time - unless you have a lot to loose??
There has been some intersting research looking at short-term (5 days) fat adaptation followed by a 1 day carb-load for aerobic athletes
inavariably fat oxidation does increase even over that short a time period and one day of carb loading was hoped to refill muscle glycogen to improve performance.
however, high end performance (a recent study examined a time trial with several short sprints) is compromised.
at best, ketogenic diets might be usable during an early prep phase or for ultra-endurance types (who don’t need a high top end)
for most, I think a moderate carb diet is the better choice and wouldn’t see much point in switching back and forth. you’ll still get adaptations to fat metabolism as a consequence of lowering carbs, you can still lose fat just as effectively.
especially given some of hte issues that can occur switching back and forth for folks