The FastDay Forum

I've had about 3 or 4 times that I've been dizzy in the later afternoon or evening of a fast day. I normally liquid fast (with tea and water, milk in tea though so not zero calories), but on the days I've had this dizziness, I've eaten something to see if that helps. It does seem to help, which makes me think it's something to do with blood sugar levels.

I have noticed though that it has only happened when I've had alcohol the evening before my fast.

Anyone else had something similar?

Funny you should post this today! Because I have been having dizzy spells today, during the period before breaking my fast at 1pm, and was wondering why today might be different from other lean days. I've now eaten and feel a lot less wobbly. And I had a pint of cider yesterday evening - I drink alcohol a lot less often since starting 5:2, so that's a break in usual habits. So maybe there is a connection. I shall monitor days with dizzy spells and see if they follow days with alcohol.

Hi both

I had a look in the scientific literature and found that alcohol can indeed affect blood sugar levels. It first causes an increase in blood sugar and then by about 12 hours afterwards a drop in blood sugar. This seems to fit in with the timings of the symptoms you are experiencing. I read that the exact effect of alcohol varies and depends somewhat on the state of your glycogen stores, so this might explain why it doesn't always happen. When glycogen stores are depleted, the effect of alcohol in inhibiting the ability of the liver to make glucose (gluconeogenesis) results in hypoglycaemia. Thus, you are more likely to experience low blood sugar after drinking if you have been low-carbing or fasting for longer or exercising so as to deplete glycogen stores (and presumably the amount of alcohol will make a difference).

Hope that helps.

Thank you Carorees, yes that is very helpful. Kentishlass, I've also cut right back on alcohol in the past year since I've been doing 5:2. This seems to be another reason to drink even less!

@KataMac I experienced dizzyness at the beginning lots. I think Carorees has it all covered there. I just want to add that I've noticed I get more dizzy when i have a low carb/low protein fast day. I have two eggs and one toast for breakfast and then a dinner later and have found less dizzy stuff. But it's all guesswork here.