Intermittent fasting is quite the buzzword in nutrition these days. But what does it mean and is it good for your health?
Fasting can be anything from a few hours to a few days. We all fast overnight and break our fast with our ‘break-fast’. That might be a daily 12-hour fast. Some will increase that by having an early dinner and late breakfast, stretching it out to maybe 14–16 hours. Others skip breakfast altogether, which would give maybe an 18-hour fast. Then there is the option of the longer fast – 24-hours or two-, three- or four-day fasts. Or there is the alternate day fast or the popular 5:2 fast, where you eat minimal calories two days a week while eating a normal healthy real food diet the other five days.
As you can see, there are many ways to fast!
The most popular regime is daily fasting for 18 hours, and fitting in all your food intake into a 6-hour window, for example, 1 pm till 7 pm. This is known as time-restricted eating or TRE.
There is increasing evidence of the benefits of fasting for weight loss and type 2 diabetes.
There are two main reasons that intermittent fasting works. The first is that there is usually a reduction in calories when eating two meals a day rather than the common three meals and three snacks per day we've been brought up to expect. The second reason is the lowering of insulin levels over an extended period of time which may increase insulin sensitivity and glucose control.
The combination of low carb, healthy fat eating and intermittent fasting is particularly effective because we tend to feel fuller for longer when we eat fats and proteins. It would be very hard to do intermittent fasting on a high carbohydrate diet as you would be constantly hungry!
There are however a few things to be careful of with intermittent fasting. The first is to make sure you don’t increase the size of your meal so that you actually don’t reduce your calorie intake. You don’t need to have two massive meals a day.
It’s also important to maintain hydration while fasting, so drink plenty of water, black coffee, green tea or bone broth, all of which are allowed in a fast.
Our hunter-gatherer ancestors probably practised intermittent fasting regularly as they would feast when they made a “kill” and then fast for the days until the next one. The three meals a day (plus snacks) habit is a modern concept not surprisingly promoted by the food industry.
As well as restricting my carbohydrate intake, I try and fit my intake of food into a 6-8 hour period. So I usually have my first meal of the day in the late morning, often around 11 am, and then try and have an early dinner around 6 pm. Social events sometimes get in the way of this, but I work around these. I occasionally do a 24-hour fast, something that I would have thought impossible a few years ago, but I now find it surprisingly easy.
A lot of people will tell you how great they feel during a fast – and interestingly have minimal hunger.
Absolutely not. You can get very good results from a low carb eating approach without fasting, but many low-carbers find additional benefits from intermittent fasting. It is a matter of finding an eating regime that suits you and your lifestyle.