On paper it sounds like a terrifying prospect for many of us, but a new kind of intermittent fasting diet could suit your lifestyle better than the 5:2 diet if you have weight to lose. Here’s what to weigh up…

Any products in this article have been selected editorially however if you buy something we mention, we may earn commission

Intermittent fasting diets  have become quite the phenomenon over the past few years - from the Dr Michael Mosley endorsed 5:2 diet  to the ‘two weeks on, two weeks off’ intermittent diet plan , alternating periods of general food restriction with eating whatever you like, within reason, has left less achievable diets (maple syrup and cayenne pepper anyone?) for dust. The fact that intermittent fasting diets also don’t normally entail cutting out food groups, giving up your favourite meals or sticking to a series of mind-boggling rules, probably goes some way to explain their popularity, as does the obvious weight loss element.

The new kid on the intermittent fasting block is the ‘one meal a day diet’, although given that our ancestors often survived/thrived on a single sitting of mammoth for 24 hours or more, it’s not exactly a ground-breaker. The concept is simple- as the name indicates, it involves getting your daily calories, nutrients and energy from one meal a day, rather than the traditional three plus snacks. Initially it might sound just as torturous as any other faddy diet plan, but as anyone who’s lolloped through a Sunday in anticipation of a generous roast can testify, the odd day of single-meal eating can be more achievable than you might think. Here are some pros and cons for ‘one meal a day’ eating…


Doctors are into it

Or at least Dr Xand Van Tulleken, who studied medicine at Oxford and has a degree in public health from Harvard. In his recently published How to Lose Weight Well  diet and recipe book, he explains why he eats one meal a day, on the whole, and how he makes it work from a willpower point of view:

“There’s a large amount of medical evidence that indicates that fasting is a safe and effective way of losing weight. The scientific research on fasting makes compelling reading (OK, it’s not the new Dan Brown or Gillian Flynn but I enjoyed it!): it does seem that you can lose weight by fasting even if you don’t reduce your overall weekly calorie intake. The way in which this works isn’t clear but some researchers describe fasting as being a good kind of stress on your body, like exercise, and that it promotes fat burning.”

“However you do it, losing weight will involve figuring out where you need to cut calories. Personally, I find most days that it’s easiest to stay hungry until dinner. Other people can’t stand this so work towards a solution for you.”

Clearly the one day meal approach words for Dr Xand- he lost six stone after shifting from grazing to more infrequent but larger meals.

You can eat what you like, when you like

Just, you know, once a day. Dr Xand explains why, weight loss wise, he finds it easier than more traditionally restrictive diets:

“My personal experience is that fasting works well much of the time. I have a nine-to-five job for quite a bit of the time in which I teach and do research. I start the day with a cup or two of black coffee and then eat all my calories in the evening in a big, tasty meal.
I don’t have to exercise much restraint on that meal and I finish it feeling full and happy. When I’m trying to lose weight, I’m going to have to be hungry some of the time, so I’d rather spend the day thinking about a hearty dinner and not wondering why I’m hungry.”

Different strokes for different folks, but if you that you function well on one big feed, it could make weight loss seem less of an effort.

It’s simple

Meals need to be nutritionally balanced, but Dr Xand underlines that eating one meal a day can lead to results without calorie counting, dietary commandments or having to source weird expensive ingredients:

“It’s really hard to gain weight on one meal per day. You can manage it if you eat pizza and ice cream but if you stick to sensible healthy eating principles you’ll be fine.”

Speaking of wholesome one day meal plans…

It’s healthy

As long as you eat well. NHS guidelines for fasting emphasise the importance of eating high energy meals to prevent muscle wastage, with a balanced carbohydrate, protein and fat content. NHS guidelines also highlight the importance of eating food high in fibre, as this “can help to keep your bowels healthy and add bulk to your meal, helping you to feel full.” Add in plenty of fruit, vegetables pulses, wholegrains and starches and you should feel satiated for longer than you might imagine.

It’s easy to fit into your schedule

Mainly because there is no schedule- have your main meal whenever suits you during the day, and the lack of  tupperware meal prep /constant juicing/ counting macros  or similar should save you time too if you’ve dabbled in other diet regimes in the past.

It gets you back in touch with your hunger

In that you may realise that you’ve previously been mindlessly ploughing through snacks without actually being hungry at all. Dr Xand reckons there’s nothing wrong with the odd pang:

“My advice is to try it and bear the following things in mind. Your body has memory of the way you used to eat. If you have a chocolate bar at 10am one day, the next day at 10am your body will expect a chocolate bar. Fasting can therefore be a shock to the system and the first day you’re likely to feel hungry. It does get better. My way of dealing with hunger is to remember that feeling hungry isn’t too bad and it is possible to function quite well when you’re hungry.”

In fact, you may find that, like personal trainer Max Lowery , food stops taking up so much headspace…

It can make you feel less “deprived” than other diets

Max told The Telegraph  that, for him at least, the one meal a day diet compares favourably to the 5:2 diet  in terms of physical results and mental effort:

“The problem with the 5:2 is that on those two days [of fasting per week] you feel deprived.”

Eating just one meal a day, however, suited him down to the ground:

“I felt full of energy, and I didn’t spend all my time just thinking about food.”

Max has now published a book on the topic that purports an arguably more achievable version of intermittent fasting, 2 Meal Day , but the fundamentals are the same in that “you’ll be in a slight calorie deficit without even realising it.” In essence, you don’t have to sit in front of a sad plate of lettuce leaves because you’re on a diet.


It can be unsafe

As you may have guessed, fasting isn’t can quite the impact on mental and physical agility, as Dr Xand warns:

“Fasting doesn’t have to come with a safety warning but it is worth remembering that there is good evidence that we do function less well when we’re hungry. You function less well when you’re full, tired, worried and all sorts of other brain states but it is undeniable that after a long fast (say, 24 hours) you’re less competent to operate heavy machinery than if you hadn’t fasted.”

Basically, don’t go operating any cranes or sitting a vital exam while fasting. Not a good combo. Ditto marathons. Also, depending on your job, routine, personal health history and activity levels, the ‘one meal a day’ principle may not be appropriate for you at all. It’s a boring disclaimer, but discuss the diet plan with your doctor or a health professional before going gung-ho on fasting. As with exercise, radically changing your routine without support can do more damage than good.

It’s not always convenient

While ‘one meal a day’ simplifies your routine on the surface, getting stressed about said meal kind of defeats the point. Dr Xand acknowledges that, despite the title of the diet plan, it’s not actually an everyday diet, and that flexibility and common sense are key:

“The amount of hunger you can cope with depends for many people on knowing how long it’s going to last and what will happen at the end of it. It’s like being sleep deprived. If you’re tired on holiday it’s no big deal; the same amount of tiredness on a Monday morning prior to a busy week is almost impossible to cope with. Similarly, I can cope with having one meal a day to look forward to most of the time. But when I’m working away from home, in places where the evening meal is going to be dismal or possibly non-existent, this means that there isn’t much to look forward to at the end of a period of hunger. At these times I tend to have three meals per day.”

It can lead to overeating

Just because you’re only eating one meal a day, that’s not a licence to faceplant the buffet, as Max clarified to The Telegraph:

“Unfortunately, people think that intermittent fasting is a magic pill that will solve all their problems. Yes, it is an incredibly effective tool to take control of your health, but it won’t cancel out eating a diet full of processed foods and sugar.”

Bingeing on junk is rarely a blueprint for good health, and that still applies even if you’re having one larger meal a day. Overindulgence isn’t the only risk; you could find that you’re coming up short in the dietary department too…

You might not be getting enough energy or nutrients

The British Dietetic Association ’s analysis of Dr Xand’s book was on the whole positive, however, the organisation had a few misgivings about the one meal a day aspect and recipes in particular:

“The ‘one meal a day’ only provides about 750 kcals per day- so expect to be hungry, especially keeping in mind that the average male and female needs 2500 and 2000 calories daily respectively, to maintain weight. A mix and match approach to the meal plans is most likely. On the one-meal a day plan, the diet is also low in several nutrients, but especially lacking in  calcium , so we would advise adding some milk or yogurt into the plan if you are going to follow this in the longer term.”

“Overall this book provides reasonably sensible diet advice, although the plan is too low in some vital nutrients such as calcium and  fibre  to follow long term.”

The bottom line? Follow your gut, eat when you’re really hungry and make sure that your plate is always balanced, satisfying and tailored to your needs, rather than to the clock, according to a fusspot recipe or based solely on whatever food is currently in fashion. See ya later kale.

Follow Dr Xand on Twitter  @xandvt  and Anna  @AnnaMaryHunter