I followed the 5-2, IF diet for a couple of years and dropped from c16 stone to about 12.7 5stone, im 5'11''.
I had not used the erg much between 2011 and 2021, and decided in may last year to get off my butt and dust it off. After Xmas 2020 i had put on a few pounds, and was following the IF plan id adopted whilst erging and hadnt found it an issue.
However, in Jan i started following the Eddie Fletcher marathon plan, having completed my intermediate goal in May, i am now following his 100k plan.
Halfway through the marathon plan i found i was finding constantly I had aching muscles and at the end of some session, i was very tired and whilst i was erging for relatively long periods this appeared to come on relatively suddenly. ( I suspect actually it was a cumulative effect and i had just not noticed it).
It was the first time that i have ever felt the need to eat more and consider my intake not just of calories but protein and carbs specifically. In my mid 20s - mid 30s I ahd been fairly fit and slim, never worried about what i ate or drank despite often exercising three or four times a day at my peak.
Apart form general energy levels i looked at my diet and found i had a much lower protein intake than the recommended values in the EF plan. I dont have the number to hand, but i was quite surprised at the apparent deficit.
So it came as a surprise to find that erging 70-90k per week should be different, stupid i know as i was 60 in jan.
Anyway, i have now reversed the decline in weight and have regained some of the weight i had lost, but i am finding the exercise 'relatively' straight forward, easy is not he right word, but i am not struggling like i was mid way through the marathon plan. No more aching muscles either.
IF worked for me, but i dont find it fits in well with erging long distances, so i am eating three meals a day when i exercise (3 times this week, 2 x 2hr sessions and 1 x 30 minutes) and restricting my intake on other days. I have lost a few pounds over the last couple of weeks but not to the detriment of the exercise plan.
So no longer If in the true sense, but varying my intake based on exercise for the day.