Intermittent fasting, often referred to as IF, is an increasingly popular eating plan that involves significantly restricting your food intake on certain days, while eating normally on others Huge claims have been made for IF around enhanced weight loss, including improved mental functioning, a reduced risk of disease and even a longer life.
So how does it work?
There are a number of ways to approach IF depending on how often you decide to fast each week and how much you eat on fasting days.
One of the most popular IF regimes is the 5:2 plan, where each week is made up of five days eating normally (preferably healthily) and two days fasting. The latter are not technically fasting days, as you're allowed to consume 600 calories on each day if you're a male and 500 calories if you're a female. The final rule is that the two fasting days should not be consecutive.
What's the evidence?
The evidence for the effectiveness of IF remains unclear, as findings from clinical trials are very limited. In fact, most research is based on animals and the data available on humans is quite old.
That said, the research findings that we have, whether they be based on animals or humans, do consistently support the popular health claims - including faster rates of weight loss. Add to this the huge volume of positive anecdotal reports from those who have tried IF, and this new approach to weight loss does appear to be worthy of consideration.
Are there any risks?
There isn't a great deal known about the possible side-effects of IF as there haven't been any formal studies carried out in this specific area. The few reports of side effects that do exist however, include:
More research is required to understand just how regular and severe these side effects can be. It is clear, however, that IF is not suitable for pregnant women, insulin-dependent diabetics and people with any form of eating disorder.Some practical tips and considerations
You're obviously going to feel some degree of hunger and even some lack of energy on the fasting days, so you should carefully consider how this will affect your life.
Fasting on days when you're busy can be a good idea so that you don't have too much time to think about eating. Exercising on a fasting day however is not advisable, as your energy levels will be lower and you're likely to feel even hungrier for the rest of the day.
Stay hydrated on fasting days with plenty of water and fruit or herbal teas - this will prevent dehydration and help you to feel more full, as well as have a mild detoxifying effect.
And finally, if you have any medical conditions whatsoever that may be affected by changes to your diet, then you should talk to your GP first before starting.