Hi Daz, I am 65 yr old grumpy old man. Have been on the 5:2 since Jan this year.
Prior to this my blood pressure was within acceptable “normal” levels. I actually took my blood pressure this morning after my 2nd fast day this week, it was 120 over 81. I am 5-9ins now weighing in at 14st 8lb having started at 15st 12lb. I am not a medical man so cannot give any medical reason for your increase readings. If you have your own monitor then I suggest you take several readings around the same time each day,3 or 4, record the time and the readings. Do this for say a month taking specific note of readings just before each fast day and just as you finish and are about to resume a “normal” day of eating. I suggest that this will, over time give a more accurate average blood pressure reading and may indicate peaks and troughs at particular times. Also diary your food intake each day for the same period, this will give a history that may help you identify certain foods that impact on your blood pressure.
Good luck.

Hi
I wrote about a similar increase in BP happening to me. I have been on the 5:2 diet for 3 months and lost 12 lbs, and 4 inches from my waist. My BP before the diet was 130/80, but on the diet it became consistently 150/90, even though I was on 40 mg/day Micardis (contains Telmisartan – an angiotensin 2 receptor antagonist). I have now increased my dosage to 60 mg/day, and BP is now down where it was. I’m very disappointed in this, as I was hoping the diet would enable me to get off my BP tablets, but in fact I have to increase them. I do not eat red meat, do not add salt, I eat a lot of vegies and fruit, I do not have any caffeine and only have no to low fat dairy, and I exercise for 1/2 hour most days (skipping and elliptical trainer). Could it be the low salt – on my non-fast days I take in about 750 mg of sodium each day. On the two fast days I only take in about 380 mg of sodium each day. Am I now getting too little salt??