Still curious about the 5:2 diet? Here’s your need-to-know

Photo credit: Photographer, Basak Gurbuz Derman - Getty Images
Photo credit: Photographer, Basak Gurbuz Derman - Getty Images

If you aren’t already familiar with the 5:2 diet by name, you’ll know it by principle. It’s the eating plan that burst onto the scene back in 2012, promising big weight loss results without the inconvenience of cutting out your favourite eats, since there are technically no forbidden foods, and in doing so secured itself a fanbase that’s still going strong today.

Case in point: #fastingdiet – as the 5:2 is also known – has 1.3 million views on TikTok as we type. 10 years may have passed since we were first introduced to fasting’s modern-day makeover, but the hype most certainly has not. And, with the many (anecdotal, at least) success stories and high-profile subscribers to the diet (Miranda Kerr, Jennifer Lopez and Jennifer Aniston are apparently advocates), it’s easy to understand why. But, does science back it as a solid weight loss solution?

While statistics about the 5:2 diet in particular are fairly scarce, intermittent dieting has been studied in depth, with the practice of fasting gaining momentum as a healthy lifestyle choice way back to the 1940s. And, if you want to go even further back, then consider this: Hippocrates, Plato and Aristotle were huge fans of the dietary pattern.

A 2021 study found the 5:2 to be effective for weight loss in the short term – more so than general, and traditionally more complex weight loss advice, and particularly when accompanied by group meetings. That said, it proved no more beneficial in the long term.

There’s also some evidence to suggest that fasting could be linked to a variety of health benefits, from reducing cardiovascular risk to improving glycemic control.

But, what is the 5:2 diet plan? Does the 5:2 diet work? And, if you want to give it a bash, where do you begin?

Here’s everything you need to know…

What is the 5:2 diet rule?

The principle of the 5:2 diet is intermittent fasting. You eat the coveted 2,000 calories five days a week – although you don’t have to consciously count calories – then on two days you slash your intake by three quarters.On fast days, this works out to be around 500 calories for women.

Many people find the 5:2 diet easier than traditional calorie counting diets, with studies showing that both methods tend to result in the same amount of weight loss, if that's your goal.

To help you feel full and load up on nutrients on your fast days, you’re advised to go for foods high in protein and fibre like fish, meat and veg. You can also choose to do your fast days back-to-back or spread them out over the week.

How much weight can you lose on the 5:2 diet?

According to Dr Michael Mosley, author of The Fast Diet, a book all about, well, the 5:2 diet, the eating plan can help you lose around a pound a week if you stick to it rigidly, and studies appear to support this. Though, bear in mind that weight loss potential isn't solely determined by calories in vs calories out. Genetics also come into play, as do factors such as illness and/or medication, stress, sleep quality, and so on.

Further research has shown that fasting can lead to a significant reduction in abdomen fat in particular, with participants of one study showing a 4-7% decrease in their waistline circumference. To reiterate, though, every body is different, and whist fasting may appear effective for some seeking weight loss, it won't be an advisable method for others.

If weight loss is important to you, your best bet is to adopt a 360-approach that takes all ares of your wellbeing into consideration, and seek professional guidance from a dietitian or GP before experimenting with any new diets.

What are the benefits of the 5:2 diet?

Evidence suggests that the potential health benefits linked to intermittent fasting actually outweigh weight loss potential. Some possible pros of following the 5:2 diet:

What are disadvantages of the 5:2 diet?

According to the NHS website you may experience some less than savoury side effects from following a diet that involves fasting. They can include:

  • Sleeplessness

  • Headaches

  • Constipation

  • Feeling faint

  • Uncomfortable hunger

  • Irritability

  • Bad breath

  • Anxiety

  • Dehydration

  • Tiredness

It's also worth noting that the 5:2 diet doesn't allow for any nuance and it lacks context. In reality, we all have varied nutritional requirements based on our genetics, our activity levels, our goals, and so on. The 5:2 diet has a one-size-fits-all structure that cannot, realistically, be appropriate for all.

Then, let's not forget the potential mental implications of following a diet that encourages restriction. This can result in disordered eating patterns, and an exceptionally difficult relationship with food.

Can I eat fruit on the 5:2 diet?

Absolutely. Technically speaking, no foods or drinks are off-limits when you're following the 5:2 diet (with the exception of fasting day, when drinking anything besides water, black coffee or herbal tea is discouraged), as the focus is on the calorie count as opposed to the specific allocation of calories.

In fact, when following a diet that involves fasting or any kind of restriction it's extremely important to factor fruits and vegetables into your meal plan to ensure you don't become deficient in any nutrients. As per NHS guidance, try to eat at least five 80g portions of fruit and/or veg a day – even on fasting days.

What can I eat on a 500 calorie fast day?

If 500 calories seems rather small, that's because, well, it is. And, in truth, 500 calories a day is not enough for many to function optimally.

That said, if you choose to follow the 5:2 diet, it's especially important to pack in as many nutrient-rich meals as possible on fasting days. Need some ideas? No problem...

5:2 diet recipes: breakfast

It’s important that your first meal of the day keeps hunger at bay. Choose nutritious foods that are high in protein and fibre to keep you feeling full past 9am. Whether you want something sweet or savoury, with these 5:2 diet breakfast recipes you’re covered.

5:2 diet recipes: lunch

Bookmark these hearty 5:2 diet recipes that are high in protein. Load-up on nutrients at lunchtime and there’s less of a chance you’ll want to face plant the free cake table at 3pm.

5:2 diet: snacks

Yes, that’s right – if you calculate your calories carefully, you will find that there is room for snacks in your 500 calorie window. The official The Fast Diet website advises that ‘fresh, raw ingredients like almonds, carrots, celery sticks, apple slices’ make the perfect 5:2 diet snacks, but if you want to shake it up a bit you fit in everything from popcorn to ice cream sundaes.

How to manage hunger cravings on the 5:2 diet

Dr Mosley admits that during the first few weeks of the 5:2 diet, you may find it particularly difficult to overcome the hunger pangs during a fast day.

However, lots of 5:2 dieters with impressive success stories have shared their tips for managing a growling stomach, and recommend taking your mind off of the discomfort by:

  • Going for a short walk

  • Meditating

  • Drinking a calorie free drink

  • Taking a shower

  • Reading a book

  • Decluttering your wardrobe

  • Pampering yourself with a hair mask, or paint your nails

Of course, if the discomfort of fasting becomes too much or unenjoyable, it may be time to reconsider whether the 5:2 diet is for you.

Who should avoid the 5:2 diet

Whilst some can reap the benefits of the 5:2 diet, it's definitely not an option for everyone.

It is advised that pregnant women and diabetics consult their GP before starting the plan, and anyone under the age of 18 is discouraged from intermittent fasting as it may not provide sufficient nutrients for growth.

The official website also advises that it is not suitable for individuals who are on medication (particularly Warfarin), those who are underweight, or anyone who has, or is at risk of, an eating disorder.

Regardless of whether or not you fall into any of the above categories, you should always consult your GP before starting a new exercise or diet plan.

What do the experts say about the 5:2 diet?

It sounds promising where weight loss is concerned, but does the 5:2 diet work as a realistic weight loss plan in the long-term? Dr Mosley suggests moving on to a 6:1 pattern once you have reached a weight that's healthy for you. As for the experts: 'This is a great way to lose weight not too quickly, and recent research has suggested that the diet also offers health benefits such as greater metabolic efficiency, improved brain function and improved glycemic control,' explains Lovisa Nilsson, nutritionist at health and fitness app, Lifesum.

'Intermittent fasting supposedly promotes more fat than muscle loss, not to mention that this diet is super simple – as long as you can calorie count you can tailor it to your taste and still eat foods that you enjoy.'

That said, Nilsson doesn't think it's an ideal diet for long term health and weight management. 'You can’t deny this diet is effective for a weight-loss fix, but I certainly don’t think it’s sustainable. Plus, you’re depriving yourself from a lot of essential nutrients two days a week, leaving you with less energy.'

To sum up: the 5:2 diet could be worth exploring if weight loss is on your agenda and you don't like the idea of cutting out foods. However, if you're looking to make a long-term change to your weight and/or your health, restricting nutrient intake is not the way forward – you'd be better off with a more flexible approach that encourages balance and moderation.

Looking for even more 5:2 recipe ideas? Why not try this Low Calorie Thai Green Curry or this Low Calorie Caesar Salad Recipe.

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