Hi all I have been doing this diet for 4days and so far have found it ok to manage. That was until this morning when I tried to do a 10 mile run and after the 3mile mark I didn't have the normal energy to run and after the 3 miles I had to run/walk to the end of the 10 miles

I have completed 3 marathons over the last 2 years so far so I am used to running. I really want to manage this diet but I really need to be able exercise properly too....... PLEASE HELP ME UNDERSTAND HOW TO WORK THE DIET WITH ENDURANCE EXERCISE