Someone recently asked me to share my thoughts on intermittent fasting, as well as the 5:2 way of eating. Although there are several benefits to regular fasting, it is not something I recommend as a long term diet strategy for anyone other than men who are trying to lean out (I will explain why that’s so specific shortly). The 5:2 diet, however, is not something I’d recommend to anyone.
Intermittent fasting is where you fast for 16 (most commonly) to 20 hours a day with an eating window of anywhere between four and eight hours. Considering that you are already “fasting” during your sleep, most fasters simply delay their first meal until at least 12pm and then stop eating around 8pm. In theory, this gives your body maximal time to use its energy reserves (i.e. break down its fat cells) with minimal glucose in your blood stream.
Some people work out fasted and eat their first meal after the gym, while others break their fast just before training. This style of eating really only works if you train in the afternoons or evenings.
As a result of an increased number of studies which demonstrate no difference between dispersing calories between greater or fewer meals, more and more bodybuilders are shifting away from the idea of eating every two to three hours to keep their metabolisms “burning” and fasting instead.
In the interests of full disclosure, it is important to note that I’ve never tried intermittent fasting – unless you can count my recent week of Ramadan.
The health benefits of fasting include an increased metabolic rate, an extended lifespan and even protection against heart disease and type 2 diabetes. Hormonally, there is a reduction in blood sugar and insulin levels and an increase in the production of human growth hormone – two things which make weight loss easier.
I can certainly understand the psychological appeals of fasting. You don’t have to constantly worry about your next meal or haul tupperware containers with you all day. This is particularly beneficial if you have a busy job. Some people naturally do not have big appetites in the morning, so it is easy for them to skip breakfast. After fasting for a few days myself, I can also see how you could lose weight more easily as it is indeed difficult to eat a huge meal after a long period without food, simply because your appetite (and stomach!) will have reduced.
If you prefer to eat big, stomach-stretching meals, eating fewer, but larger, meals will likely be more appealing – especially if you’re dieting. For example, if you are a woman dieting on 1600 calories a day, that might mean five meals of around 320 calories or two 800-calorie meals. I know which option sounds more appealing to me!
The effects on men versus women
If you’re a guy trying to add mass, I would not recommend intermittent fasting. You should already be eating what is probably an uncomfortable level of food, so eating less often is not the answer. It is also particularly difficult to meet your daily protein requirements while eating only two or three meals. For men seeking to lose weight, however, fasting can be a simple and straightforward method of dropping body fat.
The reason I do not recommend intermittent fasting to any woman – regardless of whether her goals are to lose fat or build muscle – is because of the effect it has on female hormones. Although intermittent fasting appears to improve insulin sensitivity in men, the same cannot be said for women. Fasting can also cause other hormonal imbalances in women, which can affect your sleep, skin and menstrual cycle. For more information on the effects of intermittent fasting on female hormones, I recommend reading this comprehensive article from Stefani Ruper.
Finally, I’m generalising here, but women tend to have a more emotional relationship with food and control compared to men, which means they are best avoiding any kind of eating pattern that involves restriction.
In the short-term, negative effects of fasting on both sexes include tiredness, crankiness and headaches.
The 5:2 diet
The 5:2 diet involves eating “normally” five days a week and restricting to only 500 to 600 calories two days of the week. Its appeal lies in being able to supposedly eat all the foods you want so long as you can make it through those two low-calorie days. Like most things that sound too good to be true, it is: it is 100 per cent a fad diet.
I would hope that it is obvious that I would never personally follow such a diet nor recommend it. Considering that I’m not even that much of a fan of carb cycling for the masses, the thought of restricting calories to 500 per day even just once a week makes me want to cry.
Severely restricting calories for any period of time can have long-lasting negative effects on your metabolism, which can take years to overcome and often leave you in a much worse position than where you started. Your body never knows what is coming and will constantly be in defence mode, never knowing when it might be starved again. All that cortisol will have negative impacts on your fat loss efforts.
Eat Stop Eat
There is one final popular form of fasting called Eat Stop Eat, where you fast for a full 24 hours and then essentially go wild. I really do not like this method as it seems that people use it to excuse huge binges. Which leads me to…
Fasting and the restrict/binge mentality
The biggest problem with both intermittent fasting and the 5:2 diet is that they encourage a restrict/binge mentality. For those who have past histories of eating disordered behaviour, it is simply not a good idea.
When I was doing Ramadan, those old feelings of feeling satisfied after controlling my hunger came back incredibly quickly and it was, frankly, scary.
Finally, I don’t know about you, but if I’m told to eat “whatever I want”, I could easily put down 4000 or 5000 calories in a single day. These plans that do not place restrictions on what you eat outside of the fasting window teach us nothing about healthy eating and how to properly fuel our bodies. It is therefore quite easy to go overboard and eat back all of the calories you “lost” by fasting.
Just because you fast for eight hours a day or two days a week does not mean you will automatically end up in a calorie deficit.
In my experience, I believe that most people respond best physically and mentally when they consume four or five meals per day. While macronutrients may vary according to activity level each day (more carbohydrates on training days and more fats on rest days, for example), most people should aim to keep their calories pretty consistent from day to day.
That said, it is important to experiment to find what works best for you. Just because one person loves eating eight times a day and another can happily fast all day long without bingeing at the end of it, it does not mean that you have to as well. There is no point in forcing yourself to adhere to some arbitrary eating style if it does not suit your own preferences.
Ultimately, the most important thing is finding a method of eating that allows you to be consistent and achieve your goals. Your overall caloric intake is more important than the specific timing of said calories. If you prefer eating larger meals, there is absolutely no difference between eating three meals in an eight-hour window versus “normal” breakfast, lunch and dinner times.
The only exception is that, if you have any kind of disordered eating history, you must be completely confident in your own self control and existing relationship to food before embarking on any kind of fasting protocol.
Have you ever tried any kind of fasting protocol? Would you?