As I may have mentioned before, my Dad has never been one for moderation. When we were children, he read a book by John Yudkin called “Pure, White and Deadly” and this resulted in all sugar-containing items from our cupboards being hurled onto the back lawn “for the birds”. He then read about fibre and suddenly, instead of the bug-eaten apples from our tree turning into apple pie or apple crumble, they were stewed, with added bran – yum! The real low point was when they were stewed (with added bran) IN THEIR SKINS!
So recently when he announced that he would now only be eating every other day, I wasn’t particularly surprised. “It was on Horizon and in New Scientist” he said. “Stops you getting dementia and makes you live longer.” (He didn’t need to lose weight, having obsessively walked a minimum of 10,000 steps in the hills each day for the last 900 plus days.) However, when several of my sensible friends – who are much less prone to wild enthusiasms – also went onto this regime, I thought I’d better do some research!
So, what is intermittent fasting? Basically it is any regime that involves periods where you eat what you like and periods where you eat nothing or very little. There are lots of different ways of doing this, but in the popular 5:2 approach, you restrict calories severely (to 500 for women and 600 for men) on two days a week and eat what you like on the other five. Recently it has been suggested that intermittent fasting can help with weight loss, insulin function (diabetes, heart disease) and even dementia and cancer.
So – is it a good idea?
The New Scientist article and the Horizon programme were very positive about intermittent fasting. However, most of the research has been carried out on males (many of them rats, but far more male humans than female!) The research on women is less clear cut and the effects of fasting appear to be very different between men and women.
If you google “intermittent fasting women” there is some useful information including a very detailed blog post by Stefani Ruper. If you just want a summary, see below for my take on it.
There seems to be some evidence that “grazing” (especially on carbs) is not a good idea as your body is constantly having to release insulin. Fasting gives your body a break from this and there is some evidence that it improves insulin function (although the evidence is clearer for men than women.)
Intuitive eating programmes like mine encourage you to eat when hungry and not get over-hungry. However some people who are very afraid of getting hungry may interpret this as “don’t ever let yourself get hungry” and end up eating even when not hungry, to avoid getting too hungry (pre-emptive eating!)
For these people, intermittent fasting can sometimes help them to realise that they can get hungry and they won’t actually die!
Intermittent fasting may help you remember what it is like to be genuinely hungry – this is something you need to know!
Some people find it easier to eat a rigidly defined small amount some days and what they like other days than to eat moderately all the time. It can remove the constant thoughts of food that many people have, as there is no “shall I or shan’t I?” decision to be made. So, it may be an easier way to lose weight than permanent moderation. It can be a way to reduce food intake without feeling you are “dieting” because you know you can always eat lots tomorrow!
It can be an effective way to lose weight, but it really needs to be a long term lifestyle choice, otherwise it is just another diet and you’ll put the weight back on when you stop.
If you aren’t overweight (and particularly if you haven’t gone through the menopause), I don’t think the research at this stage supports using intermittent fasting for health reasons (e.g. to prevent dementia or generally prolong life.)
Fasting may make you feel very alert and energised. However if this translates into not being able to sleep, you may feel good short term but actually be technically stressed. Long term you may compromise your adrenal glands.
Some women actually gain weight when they start fasting. I assume the body interprets this as a stressor/ indicator of famine to come and finds a way to put on weight.
If you have a history of eating disorders, I wouldn’t recommend it. It is easy to get obsessive and go “just a bit longer”.
It may push you back into the “diet mentality” where your brain and/or body assumes food is scarce and urges you to eat more and store more fat.
As with all eating approaches, there is no right answer. You just have to experiment. Looking into IF has caused me to experiment with eating breakfast later if I’m not hungry first thing. Previously I thought I needed to eat something before mucking out the horses or I’d feel weak. But (especially if I eat low carb the day before) I can wait till 10am or even later some mornings before I’m hungry. If I had an early supper the night before, that is actually quite a long time without food. Some people find that having an “eating window” of say 10am to 6pm gives them the benefits of a fast without getting too hungry.
So, the bottom line seems to be – listen to your body! Intermittent fasting MAY help you lose weight, get more in touch with what it really feels like to be hungry, lose a fear of hunger and/or stop obsessing about food. However, it may have the opposite effect! And it could make you ill if you overdo it and don’t listen to your body, particularly if you are already thin.
One thing I would take from the positive research on IF is that it is perfectly safe to let go of any belief that you “need” to eat breakfast or three meals a day, or indeed any other dictate that makes you eat when you’re not hungry! Whatever you try, approach it with a spirit of exploration as to what works for your body, and be gentle on yourself (i.e. remember those Enlighten Programme principles!)