DR MICHAEL MOSLEY explains how sleep patterns affect the appetite


Trying to lose weight? Well, one of the things you must do if you want a slimmer and healthier body is to get enough sleep. For most people that means seven to eight hours a night.

If you try to get by on less, as many people do, then this will mess with your mood and your body’s ability to control your blood sugar levels, which can lead to over-eating.

To see what impact cutting back on sleep can have, a couple of years ago I took part in an experiment organised by Dr Eleanor Scott, who works at the University of Leeds.

We recruited a group of healthy volunteers and, under her supervision, fitted them with activity monitors and continuous glucose monitors, so we could see what was happening to their blood sugar levels.

Then we asked our volunteers to sleep normally for two nights (so we had a baseline to work from), have two nights where they went to bed three hours later than normal, followed by two nights where they could sleep for as long as they liked.

Naturally enough, being an avid self-experimenter, I joined in. I was unpleasantly surprised by just how much my blood sugar levels rose on the days when I was sleep deprived, and how hungry that made me.

The same was true of my fellow volunteers. When we met to get our results from Dr Scott, everyone complained about having the munchies. As one volunteer put it: ‘I wanted lots of biscuits and I didn’t just have one. I’d go for ten. I wrote it down on my diary — ten custard creams.’

‘Is that unusual?’ I asked him.

‘Well, that’s certainly unusual for breakfast!’ he replied.

All of us, whether we had feasted on biscuits or managed to stick to our normal diet, saw marked increases in our blood sugar levels, to the point where some previously healthy individuals had levels you might expect to see in borderline type 2 diabetics. These problems resolved after a couple of good nights’ sleep.

So why does this happen?

Dr Scott said: ‘We know that when people are sleep-deprived, they often crave sweet foods, which could explain the custard cream cravings. We also know that if you’re awake when you’re not meant to be, you produce more of the stress hormone cortisol, and that can influence your appetite as well as your glucose levels.’

As Dr Scott pointed out, poor sleep also disrupts hunger hormones such as leptin and ghrelin. These work together to manage appetite. Leptin reduces hunger, while ghrelin promotes it. When researchers at the University of Chicago recently monitored hunger hormone levels and appetite in a group of volunteers, they saw some dramatic results.

As part of this study, the volunteers were asked to get by on just four hours of sleep a night for six nights, followed by another six nights when they could sleep as much as they wanted.

Tests showed that when they were sleep-deprived the volunteers had 18 per cent lower leptin levels and 28 per cent higher ghrelin levels, reflected in the fact that they also reported feeling much, much hungrier. There was a particularly marked increase in their preference for sweet, salty and starchy foods.

The message is, if you want to get your hunger hormones working with you rather than against you, you must prioritise sleep.

That’s why establishing a proper sleep pattern is part of my new diet, The Fast 800. By tracking people who’ve done our online course (see thefast800.com) we’ve shown that you can lose up to a stone (6kg) in three weeks.

As I explained at the start of this series, in Weekend magazine on Saturday, the Fast 800 programme is based on nourishing low-carb, low-calorie, Mediterranean-style meals, centred around vegetables, pulses, dairy, nuts and seeds, and lean protein such as chicken and fish.

It starts with rapid weight loss, where you limit your intake to 800 calories a day every day. This is followed, after a few weeks, by switching to my intermittent fasting pattern, now known as the New 5:2 diet.

A major benefit of the 800-calorie approach is that you lose substantial amounts of weight, fast — which is highly motivating.

Importantly, it also helps you to reset your metabolism and appetite so, within a week or so, you should feel less hungry, more energetic and clearer headed — as well as lighter on the scales.

Today, we continue our exclusive Fast 800 recipe series, sharing some of the tempting and delicious suggestions for soups and shakes, created by my wife, Dr Clare Bailey.

Our soups are as tasty as they are filling. The recipes mainly serve four, so you can take one portion to work for lunch and store extra portions in the fridge for a few days or put them in the freezer. Or you could use them as part of a family meal.

Although we recommend real food first, we know that shakes can be very useful as meal replacements to help you keep on track.

They’re also very handy for anyone who works shifts, is on the go or travelling and therefore finds it hard to make sure they can get a healthy low-calorie meal.

Our nutritious shake recipes are likely to be healthier (and cheaper) than most you buy in shops or online, which tend to be high in sugars and starchy carbs.

If you don’t use dairy, we suggest adding unsweetened almond milk (which has 13 calories per 100ml), or oat milk (44 calories per 100ml)

Soups and shakes can be a very useful fast-day option when you are following the New 5:2.

All these recipes are taken from our new book, The Fast 800 Recipe Book, which is brimming with more than 130 brand new recipes, as well as health advice and tips on how to take control of your own health with the foods you eat at home.

By for the Daily Mail

We can’t stress enough how important it is to drink plenty of fluids when you are on this diet.

This is particularly the case during the first week or so of the Fast 800 when your body is still adapting to the diet and trying to reset your metabolism. During this period you may feel light-headed and have the odd headache, so drinking plenty of fluids will not only help you to feel fuller, but also help to combat any tiredness and keep your energy levels up.

This is especially important on fast days, when we suggest you aim for an extra 1–1.5 litres of calorie-free fluids, mainly as water.

It is best to avoid drinks with sweeteners, as they can upset the good microbes in your gut.

They are also likely to sabotage your attempts to retrain your taste buds, as sweeteners are often many times sweeter than sugar itself.

If you drink a lot of artificially sweetened drinks, you may need to reduce them over a matter of days or even weeks to avoid withdrawal and cravings. If you must use a sweetener, Stevia is probably best.

Do try some of these lovely ways to add flavour without significant calories. These drinks can be enjoyed any time and won’t interfere with fat-burning.


Our first choice is always tap water, either straight from the tap or filtered.

If you’re inclined to forget to increase your fluid intake, try keeping a jug or bottles in the kitchen or on your desk at work. Aim to finish them by the end of the day. Or carry a bottle round with you.

The Fast 800 Recipe Book by Dr Clare Bailey and Justine Pattison is published by Short Books, £16.99. ©Parenting Matters Ltd. To order a copy for £13.60 call 0844 571 0640. P&P is free on orders over £15. Offer valid until 22 June 2019.


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