5:2 while marathon training

[elspethmcgillicuddy]

I'm hoping for some advice about fasting and marathon training. I started 5:2 a year ago and love it. I started running about 6m before I started fasting and in the past year I have run 4 half marathons with no problem.

I am running London Marathon and in the past few weeks since my long run distances increased beyond 14 m I have found I am a lot more tired with major energy dips. I am also finding myself binging a bit on feast days. On fast days I occasionally feel a bit woozy and out of it. This hasn't happened since I first started a year ago. I do run on fast days but up to a max of 5 easy miles (I've always done this). I also don't fast the day before my long run. I'm currently running 30-40m per week.

I guess I want advice on whether to give up 5:2 until after the marathon. I think it might help me train better and feel less tired in general.

If it helps I have a BMI of 22 and haven't lost any weight with 5:2 but have loved the ease with which I have maintained my weight. I had hoped to continue IF forever and feel scared at the thought of giving it up. Please help!

I'm trying to do the blood sugar diet 800 kcal per day and train for 10k. I have no idea how you manage 5 miles on fast days! I'd leave off dieting until after the marathon. Is not worth messing up your marathon for a diet. You might never get a place again so treasure it and the training.

Good luck for the marathon.

Thank you. I was supposed to fast today and normally would having nothing. I had some natural yoghurt, a banana and a small handful of nuts at lunchtime and felt SO much better. Think I will add in a small meal like this for now on fast days.

Long runs are tough when you are fasting, because your body struggles to burn sufficient fat as fuel for that longer period.

I suggest you stop FDs for a couple of weeks as a trial.
Instead do daily 16:8 or even 14:10, but aim to stay within TDEE.
If you are maintaining with 2 FDs, you may need to train yourself to eat to TDEE, say via mfp.

I recommend you cut right down on alcohol, sugary treats, junk food etc, to help your training and to keep calories within bounds.
Concentrate on protein, lots of veg, beans & pulses, fruit, nuts, plus complex carbs for sustained energy.

Weigh at least weekly, for a reality check:
Longer runs increases appetite, so you tend to eat more if you don't monitor intake - a surprising number of folk overshoot and gain weight

With the increased exercise, you might need to eat more carbs for fuel, i.e. tweak your macronutrient proportions