5:2 - Is intermittent fasting for you?
You spend five days eating whatever you like and two days consuming a maximum of 500 calories per day.
Initially, when I first heard about intermittent fasting, to me that sounded like 2 days of mental torture, paired with 5 days of binge eating and clogging up my digestive system. Then I looked for evidence.
If we fall back to the basic calories in, calories out idea - consuming 1000 calories max in two days, puts the average adult at a deficit of 3000 calories. So if you're consuming 10,000 calories (2000/day on average) for the other 5 days, depending on where you started weight wise, you may lose up to 6kg a week. Sounds great – But what about when you're hungry?
"Eat whatever you like"
Followers of the diet report that the fasting days help them to reduce their appetite as they train their body to survive with less food aka "shrink their stomach". This in turn (reportedly) allows them to stick to eating a normal amount rather than binging on food all day long on the non-fasting days. Therefore maintaining their overall weekly calorie deficit - therefore eating less overall, hence the weight loss. Makes sense.
But you know what else helps to shrink your stomach? Consistently eating a little less than your usual everyday, and making every mouthful count.
Is there more to it than just eating less?
Basically yes - and the bottom line is that you need to eat really well. If you're cutting back on a lot of calories/food - then you're reducing your capacity to ensure your body is getting the nutrients that it needs in the amounts that it needs to function optimally.
That means its even more essential to eat a variety of wholesome foods and making each mouthful count. Results from this way of eating also rely on not over-eating on your normal days, how often you exercise, how active you are in your daily life, and what your starting position is (weight and health wise).
Despite what you've been told for so many years - new research has reduced the strength of evidence suggesting you must always eat breakfast, and that consuming 6 smalls meals a day is better for you than 3 larger ones. There are benefits to eating breakfast and smaller meals, absolutely! But the current pool of evidence is refocusing us back to quality not frequency.
The quality and amount of what you eat is much more important than when it's consumed.
Should you try it?
- Are you example person number 1 who works a lot, meals aren't that important to you, and you're happy to fast 2 days, because you don't eat much during working hours anyway, then on the slower days you don't ever really feel the need to overeat anyway?
- Or are you example person number 2 who works from home, has to prepare family meals, kids meals, has time in the afternoon or evening to relax and likes to snack whilst watching TV, really enjoys food and eating (I'm with you here!), and going 2 days with only 500 calories ("what does that equate to anyway?!") is a tough ask?
- Or are you example person number 3 who has a strict "If it fits your macros" style gym-fuelled eating regime, who isn't afraid to sacrifice meals, avoids "cheating" when a goal is near, and is used to restrictive eating, but has a bit of a plateau and is wondering if the "gains" or "shred" will be worth those fasting days?
These are really broad examples and many of you are a mixture or perhaps none fit your bill. That's ok. From previous clients and my studies involving motivational interviewing - experience tells me that person 1 will likely tolerate intermittent fasting well. Person 2 will struggle, and person 3 will persevere as long as the others who have tried it and seen results, then move to something else if it doesn't work for them.
This way of eating is not for everybody. Those with Type 1 and Type 2 insulin dependent Diabetes, this is a no-go zone. Unless you're adamant you want to try it and can find a health practitioner willing to coach you through it and be legally allowed to adjust your insulin dosage. Based on current evidence, I do not recommend this for you.
But what is the evidence?
Some studies are for it; some researchers aren’t quite convinced. Most studies touting the benefits of fasting come from those examining the diet for rats. Most of the inconsistent results come from human studies.
“Many animal studies have shown intermittent fasting to increase life span, stress relief, insulin sensitivity and improve CVD by reducing blood pressure and heart rate; however the research in human subjects is not conclusive.”
It is also said to kick start your body into increasing its metabolism of your energy sources e.g. fat, stored glucose and ketones. Just enough so that you get an effect, but not so much that you end up in ‘survival mode’.
This seems to be a key difference when comparing low calorie fad diets to a fasting regime. The effects seem to be beneficial if fasting is in short bursts e.g. one day. But long term reduced caloric intake e.g. fad diets and quick weight loss plans can result in igniting “survival mode” via starvation. This eventually leads to metabolic damage, and your body goes into full-fledged ‘save the fat’ mode.
So later on when you resume eating more, you’ll pack back on the kilos and then some, just incase it happens again. This doesn’t seem to be the case for intermittent fasting, and as a result, may for some, prove an easy way to keep their intake lower than usual and maintain steady weight loss relatively easily.
Additionally, in one small study “fasting had the effect of culling old and damaged immune system cells and replacing them with fresh and more effective new ones.” Showing small but potential benefits for those undergoing cancer treatment, though more research is needed before we jump to any conclusions with potentially serious consequences in critically ill people.
Is it really worth it?
All guided diets suck. Your reducing your intake of food, and food is an everyday pleasure. It’s restriction, it’s mathematical, it’s scheduled and it may seem unnatural. The only diet I recommend is an individually tailored one based on wholefoods – this means making swaps, not stops for the food you love.
However, if you can tolerate 2 days a week of feeling pretty damn hungry, a little dizzy, fatigued, headachy, with brain fog (apparently these symptoms only lasts a few weeks till your body adjusts), and then be satisfied knowing you can and will eat a healthy, balanced diet, without overindulging, on the 'eating' days; plus you’re used to counting calories, you don’t have to cook for others, and/or can easily adjust your social life to sit it out and “just have water” – then it could work for you. And it seems there is no real apparent harm in testing it out.
But in actual fact, eating less in general (and in turn reducing your weight) has been shown to have pretty much the same health benefits including improved insulin sensitivity, reduced risk of obesity, diabetes and heart disease, improved longevity and quality of life, as well as weight loss and weight management.
So where does that leave us?
As Brad Pilon puts it, the man who apparently brought fasting to mainstream: “The end goal of intermittent fasting, at least from my view, is simply to allow people to be comfortable with the idea that it’s OK to eat when they are hungry, and not eat when they are not hungry.”
Regardless of whether you fast 2 or 3 days a week then eat up well on the remainder, or you just cut back on a couple of snacks, glasses of wine, or that second helping each day – being comfortable with listening to your body and eating when you’re truly hungry, and not eating when you’re not, is something we can all benefit from.