The FastDay Forum

Hello all

I have been lurking here since starting 5:2 about a month ago and having found the advice of you all to be invaluable I knew exactly where to turn with my query.

I have noticed over the last few weeks that my long distance vision has become more blurred, which is only really noticeable when I'm driving. I wear contact lenses and assumed that I needed a stronger prescription, so I booked an appointment at the opticians for this morning.

I was checked out and the optician found it strange that I felt like I needed stronger lenses when actually I didn't. Then she asked whether I'd ever had any problems with blood sugar, and suggested that I get myself tested, as problems with this can cause periods where vision is blurred, which may explain why I sometimes think I need different lenses when I don't.

I have never had any tests or anything for blood sugar - never felt any need to, and so I thought this was strange. Then it suddenly dawned on me that the problems started around the same time as when I started fasting.

I can't say for certain whether my vision is any worse on fast days or feast days, but I will keep an eye out for any patterns from now on.

I just wondered if anybody else had ever come across anything similar and whether you think that the two things could be connected?

Thank you

[Debs]

That is interesting as I was sat at the computer yesterday at work and noticed that my sight was a bit fuzzier than usual, and I was fasting yesterday. It has improved somewhat today but I was wondering if I needed to get some stronger reading glasses. I had laser surgery on both eyes last June but don't think I can attribute it to that. I have got rid of my short sightedness but still need glasses for reading. Be interesting to see what other people say.

[carorees]

Well high blood sugar has long been known to damage the retina but during fasting blood sugar is greatly lowered and it's a long term thing anyway (high blood sugar for years before retina changes are seen).

However, high ketone levels can also cause blurry vision. Diabetics have to try to avoid ketone production as it indicates that insulin treatment is wrong. But for people who are fasting, producing ketones is good because the body uses them for energy when the glucose stores (glycogen) have run out. It means you are burning fat (hurrah). Ketones have also been implicated in the improvements in nerve function/memory seen with fasting in rodents.

It is quite surprising that your ketone levels are high enough to affect your vision, but it could be the case. You could invest in some ketostix to test your urine and see if the levels are high at the times when you notice your vision is affected. Ketosis also causes a bad taste in the mouth and bad breath, so if you have these too I think you can be fairly sure what is affecting your eyesight.

If you are noticing a permanent change to your vision it would be worth getting checked out by the doctor to exclude high blood sugar as the cause. If it is just when fasting, my bet is that it is due to ketosis.

When I did the Lighterlife diet many moons ago we had to test our urine for ketones to check we were in the right zone for fat loss. I found that if I did not drink enough then my ketostix indicated that my ketones were too high. Maybe try drinking more water?

I've been on 5:2 since christmas, and have just been diagnosed with central serous chorioretinopathy. My symptoms include blurred vision.

I'm not suggesting that 5:2 caused it, it's most likely stress-related, but I have since gone back to a 'normal' diet until my sight recovers.

I would suggest you go to see an eye doctor rather than an optician. You only get one set of eyes, so best to get it checked out properly.

This is interesting. I noticed that my reading vision (computer screen and books etc) has been worse than usual this week and like Debs thought I just needed stronger reading glasses. Having read posts on this thread and thinking about it, it has been quite a sudden deterioration. I don't think it was worse on my fasting days (Monday and Wednesday) but my vision does seem to be better now at the weekend.
I have been on 5:2 since 28 January. Last week was the first time I noticed this problem. It was also my highest weight loss week since starting - 4lbs - maybe there is a connection?

I have also noticed sight differences although I don't think it was on a fast day. At work, we are not allowed fluids on the shopfloor and can only drink during lunchtime and tea break. Perhaps, as Little Red One says, it is the lack of water that concentrates ketones. Will know to keep a waatch on this in future.