The FastDay Forum

Wonder if u can advise? Am on maintenance 1000 cals mondays and thursdays. Last thurs felt giddy and a bit lightheaded. Decided to try 6:1 so today ate 150 cals lunch. Evening meal was 300 cals but on finishing meal felt giddy and began to faint, stumbled to floor and OH helped me up and onto sofa. Took a while to recover. OH said i prob need to eat more. Dont want to stp 5:2 but as im at target size maybe i should take a break from it for a while? OH gave me some food and i did feel better.
Your advice welcome!

[carorees]

Hmm, how long have you been practising fasting? Normally these kinds of side effects are seen at the start when the body is not so good at fat burning and this causes dips in blood sugar. One possibility is low blood pressure, another is that some people feel light headed when in ketosis. The fact that the feeling faint came soon after the meal could be a sign of low blood pressure.

I would get your bp checked. Sometimes, a sudden decrease in blood pressure can cause these symptoms, especially if you're not used to a lower blood pressure. Sometimes your body adapts.

You say you are on 1000 cals on fast days but only mention 450 cals worth of food...I should have thought that 1000 cals would not cause problems with low blood sugar, 450 might if you don't have much reserve since reaching your target weight.

I'd suggest sticking to the 1000 cal fast days.

Thanks caroline, ive been on 5:2 since august, no problems until recently. On thursday had around 800 cals but decided today to have mondays as 500 cals and eat normally on thursdays. I do have low BP normally anyway. Choice is whether to stick with 5:2 having 1000 cals on 2 days or to try going back to 7 days of "normal" eating, which would probably be much smaller portions than i ate before 5:2. Even 2 x 1000 cal days might mean i lose weight, which i now dont want to do!

[carorees]

Why not one day on 1000? I would think it's worth keeping on with fasting as a return to normal eating might well lead to weight gain. Alternatively, think about fasting rather than calories so, skip breakfast or lunch a couple of times a week.

Thanks will try the one day with 1000 cals and see how that goes. I don't eat breakfast anyway, so hopefully this will help me maintain.
This forum is great, i have learned a lot and you are all so supportive.

That sounds like a blood pressure or other kind of problem. You don't normally stumble around and feel light headed as a result of fasting for less than 24 hours. Perhaps you want to see a doctor?

Yes, I would recommend you see a doctor. Feeling dizzy may be caused by an electrolyte imbalance or low blood sugar.
Could also be some kind of postural hypotension from getting up quickly.
All in all it's an unexpected side effect, be safe, get it checked...
Peter Smith (RN)

Some of us have had palpitations on fasting days (there is a thread on that). Although they normally shouldn't lead to fainting, some types of arrythmia may. Agree on the postural hypertension, but if you were fainting while sitting down (not trying to get up) I would think that was strange.
I suppose you would have mentioned if you were taking anti-hypertensives

Thanks everyone. No I was standing up, after just having eaten. Not taking any medications except 125mcg thyroxine (having a blood test for this tomorrow due to reading about thyroxine & weight on this forum). Have natural low BP. Due to constipation since being on 5:2 seven months ago, am now taking daily Lactulose - which I guess could upset electrolyte balance?

[carorees]

My bet is hypotension, coupled perhaps with lower salt intake due to fasting and possibly insufficient fluids. Drinking more and including salt in your diet can alleviate hypotension problems.

My BP is around 90/60, although GPs have always said this was OK. I am increasing fluids and salt, still don't feel any different, i.e. don't feel well. Would you expect the thyroxine to be too high for me, given I've lost quite a lot of weight?

We could expect all kind of things, and hypothesize even more, but nobody online can give you a reliable answer, as much as we want to. As long as the NHS still exists, you might consider a visit if symptoms persist. Checking your thyroid status might be a good idea anyway.

[Betsysgr8]

Get checked by a Doctor. As for the thyroid medicine, weight changes have always had an effect on my dosage. Is your heart-rate faster than it used to be? It's very possible your thyroid medicine will need adjusting. Good luck to you.

[carorees]

I wouldn't be surprised if your thyroxine is too high...did you get a blood sample sent for testing? If it's too high you would definitively feel rubbish. When do you get the results?

Thanks caroline! I am going to GP tomorrow, i had the blood test tuesday so she should have the results. I do feel rubbish and it would be good if the solution was just a change in the dosage. Up until recently have felt really good on the 5:2 so i hope this will be sorted soon.