I am doing something like this now, but 4-5 days is too long for me.
I am running 3 days low carbs (around 50-70 g mostly from veg), then 'refeed' one day, so I have carbs in every meal, but it is low fat.
Our bodies adapt very quickly to anything we do to them.
We have a very long prehistory of very harsh conditions, and few things have come out of this:
1. Our ability to store energy for future use (FAT)
2. Our ability to slow the metabolism to adapt to whatever the calories are so we can survive.
Have you ever noticed when dieting in a very strict manner you hit a sticking point, give up, have a wee pig out and you find you have lost weight? The body no longer thinks it is starving, so it doesn't have to slow down anymore.
This is related to our leptin and gherelin (sp) hormones.
Mixing up the macros and calorie intake makes sure your metabolism does not slow down, which would also slow fat loss.
I am not sure if this is true, but I think Arnie used to run 4 days low carbs, then one day high.
Jay Cutler has run a similar thing but more like low, low medium low high repeat.
x
x
x
T