Most diets focus solely on food. They are concerned with the types and quantity of food that will help get you to a particular endpoint. They provide rules or guidelines to follow, but they don’t focus much, if at all, on what’s happening inside your body.
When I successfully lost a stone and a half with Weight Watchers 20 years ago (which I regained just six months later), I was overly hungry much of the time. I watched the clock until the next mealtime and struggled through on raw carrots and rice cakes – it was one point for three rice cakes if I remember rightly! I was continually battling against what my body was telling me.
I was hungry and I needed to eat, but the rules meant that I couldn’t afford to. If I used the points up too early, I’d be in total disarray by bedtime.
What you’ll learn with Appetite Retraining is that it doesn’t have to be like this – learning to recognize how hungry or full you are, and eating in tune with that, is the key to losing weight without putting a strain on your body.
In the long run, as you settle into a pattern of eating the right amount of food to keep you going until the next meal, perhaps with a snack to tide you over if needs be, you can learn to listen to your body’s natural hunger and fullness signals and trust them to guide your eating.
You will be in harmony with your body, and your body will respond well to that. There will be no more unbearable waiting while you struggle with feeling extremely hungry. You’ll see how allowing yourself to get definitely, but not overly, hungry by each meal allows you to lose weight.
And by stopping eating each meal when you’re just full – not stuffed – means you’ll definitely be hungry by the next meal. The way that your body and brain regulate eating is mind-bogglingly complex. It is governed by two systems: the system that deals with self-regulation (homeostasis), which is controlled by the hypothalamus, and the system that deals with pleasure and pain – which is controlled by the limbic system.
Even having just a rudimentary understanding of what’s going on inside your body and brain can help you think about how to eat and how to work with your biology and psychology, not against them.
How we’ve lost our way with food
Over recent decades, the way we eat has become increasingly divorced from the way the human body evolved. Over millions of years, our digestive system evolved to allow us to eat a meal that gives us enough energy for a few hours.
Once that meal is used up, signals from our gut and other organs tell our brain that it is time to eat again. We experience these signals as hunger. When we eat, the hunger signals are switched off and we start to register feelings of increasing fullness and we have the energy we need for the next few hours.
Our brains evolved to seek out food and respond to the sight or smell of it by salivating so that our body is ready to digest it. Finding food took time and effort and preparing it for eating was demanding work.
But food is no longer scarce in much of the developed world – in fact, it’s available ready-to-eat, just about everywhere and often round-the-clock. In this new environment of plentiful and often cheap food, many of us are confused about what to eat.
This is true even for people who are highly competent, successful and intelligent. I’ve worked with doctors who understand the workings of the human body better than anyone, and are aware of the damage that overeating causes to the body, but who feel bemused and embarrassed that they themselves can’t always control their own eating.
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Your gut and how it works
Humans have a stomach that is about the size of a fist, which is supplied with food by the oesophagus – a muscular pipe that moves food from the mouth after swallowing. After passing through the stomach, food enters the small intestine (ileum) and from there the large intestine (colon).
These two parts of the intestine make up a muscular tube several metres in length in which nutrients and water are absorbed into the body. Once food has completed its journey through the intestine, anything left enters the rectum and is expelled into the toilet as poo.
This structure and function of the gut, from mouth to anus, means that we’re adapted to eat meals with gaps between them. How long those gaps depend on the size of our meals, and what foods we consume.
We are not cows. We do not have to graze continually to supply our bodies with the nutrients and energy needed for life. And we are not snakes – we can’t ingest an enormous meal and spend days digesting it. If we do start to eat like cows or snakes, we are likely to pile weight on.
A key biological process swings into action once the food from your last meal has finished digesting. Your body switches from digestion to repairing damaged cells, and cleaning your gut. In that gap between meals when you’re beginning to feel hungry, your body is putting its house in order.
Two particular features of how the gut works are key to Appetite Retraining.
The stomach is like a pouch with a valve at its entry point from the oesophagus (the cardiac sphincter) and another valve at its exit point into the duodenum (the pyloric sphincter). It’s made of muscle and as food pours in, the stomach wall expands. Specialized nerve cells in the wall of the stomach (mechanoreceptors) is activated when this stretching occurs and they send messages to the brain to say that food is entering the stomach. They register the volume of food you’ve eaten. Because these are nerve cell (neuronal) transmissions, they are super-fast like high-speed broadband.
The small intestine and large intestine are where absorption of food takes place. Gut hormones, such as leptin, help to break down food and send signals to the brain about the food that is being digested. They register the metabolites (constituent products of the breakdown) of what you’ve just eaten. Hormonal signals are chemical (not neuronal) and these travel via the bloodstream.
The speed of these signals is much slower than the signals from the mechanoreceptors in the stomach wall. More snail-mail than fibre optics. It takes upwards of 20 minutes for the hormonal information from the gut to register with different brain centres.
Both the immediate neuronal messages from the stomach and the slower hormonal messages from the intestine are part of our Appetite System’s way of telling the brain that we can stop eating as we’ve had enough food.
How hunger and fullness work
We experience these messages (neuronal from the stomach and hormonal from the intestine) as a sense of increasing fullness, and it is the immediate neuronal signals from your stomach that you need to re-learn to listen to, in order to gauge how much you’ve eaten.
Because the mechanism is due to the stomach wall stretching, this is all about the volume, not the content of what you’ve eaten. So the same volume of steamed broccoli is registered as the same volume of French fries or ice cream or lasagne.
If you ignore the immediate signals being registered from the mechanoreceptors in your stomach wall, you’ll have to rely on the hormonal signals from your intestine. But, as we’ve seen, these take 20 minutes or so to fully register, and you can consume an awful lot of food in those 20 minutes.
Think of Christmas dinner: that celebratory meal can involve serious over-catering, but you don’t feel completely stuffed and slightly drugged until after you’ve polished off seconds of Christmas pudding, by which time you’re groaning and full of regret, and you fall asleep in front of the TV.
If you were a snake, this wouldn’t matter and you’d hide under a log for a day or two until you’d digested it all. But being human, on Boxing Day morning your internal clock (see below) is telling you it’s time to eat, and you’re off again.
When you learn to listen to the fullness signals from your stomach, you can retrain yourself around portion sizes, so that you eat what your body needs for the next few hours. In the time following your last meal, your body is at work digesting and absorbing the goodness (or otherwise) from the food.
The phenomenally complex system that governs this extracts different elements from the food (glucose, fatty acids, amino acids, vitamins etc) and gut hormones send messages to the brain about how far the process of using up the last meal has progressed.
As nutrients are transported to where they are needed or where they are going to be stored, hormones (including ghrelin) signal that the food from the last meal has now been used up and your body have to switch to using up its energy reserves.
These signals are experienced as increased hunger and they only begin once we switch over to using up stored energy. That stored energy is fat, so those signals tell us that we are now burning a bit of stored fat.
That’s exactly what we want in order to lose weight. Appetite retraining teaches you to use those signals of increasing hunger to guide when to start eating and to tolerate feelings of mild hunger so that you wait to eat until you are definitely hungry.
In that space between mild and definite hunger, you will burn a bit of fat. (It’s not this simple in reality, but this is the gist of what happens as you get hungry.) By burning this fat, your body has been given a new bit of energy so the hunger signals are switched off again.
This pattern of switching off hunger signals because a bit of fat has been burned for energy means that tolerating mild hunger comes in phases – it’s not continuous. In a while – maybe 15 minutes, maybe half an hour – you’ll begin noticing sensations of hunger starting up again.
And they will get stronger each time they’re triggered, and it’s your job to notice when these sensations are definite hunger as opposed to slight hunger. To enable your body to burn a little stored fat before each meal.
If waiting to eat until you’re definitely hungry makes you feel uneasy or anxious, don’t worry. The purpose of feeling hungry is to orient us away from other things and towards seeking out food. It’s a basic part of how our Appetite System works to keep us alive and healthy by getting us to eat. The next part of this system we’ll look at is the role our taste buds play.
Your taste buds
Your taste buds are receptor cells in the mouth and nose, which detect certain qualities of food and drink. These are salt, sweet, bitter, umami and sour. Combinations of these give rise to flavour and, together with other qualities of food, such as fat content, produce the overall level of palatability of the food.
When our taste buds are more sensitive, we experience more flavour – and they are at their most sensitive when we are hungry. This is why the Ancient Greeks described hunger as ‘the best seasoning’.
So a particular food is eaten when you’re hungry tastes much better than the same food eaten when you’re not, and when you increase the amount of pleasure you get from eating, your appetite is more satisfied.
Part of the system that helps us know when to stop eating is taste-specific satiety – our taste buds become less sensitive to the food we are eating, bite by bite. The first few bites of any dish are the tastiest, but if we then switch to different food, that new taste hasn’t been desensitized to the same degree, so we’re likely to enjoy that more than we would if we continued eating more of the first food.
This is why pudding may be alluring, even though you’ve had the fill of your main course and why the babies are interested in the dessert when they’ve rejected any more main course.
You’ll be very familiar with the way that the smell of baking bread or fresh coffee activates your appetite. Your mouth may be watering now just reading those words. We’re born with an automatic reaction (‘unconditioned response’) of salivating in response to food, just like Pavlov’s famous dogs.
Because the volatile compounds in food are detected by our noses, we learn to expect food when we smell it – and when we expect food, our appetite system kicks into action whether we’re hungry or not.
The sight of food itself is enough to activate our digestive juices and sharpen our appetite. When you catch sight of food that you know you love, your memories of the pleasure of eating it are triggered, and you are more likely to seek it out without even realizing it. This is a subconscious process and happens even if the sight of the food is too quick (subliminal) to be registered consciously.
The lure of food
The sight of food we love activates our desire to eat it, and advertisers and supermarkets know this – that’s why they use visual images of food to get us to buy more. Later, I’ll explain how to deal with the visual triggering of your appetite, so that you can stop yourself eating just because you’ve caught sight of a cake advert out of the corner of your eye, or had a fleeting image of the ‘golden arches’ M as you speed along the road.
As we begin to chew and taste our food, the process of digestion begins and it’s where we hope to detect danger in the food. If something is poisonous, or the food has gone off, our sense of taste may pick that up and force us to spit it out.
Your brain has a massive part to play in appetite retraining. After all, it was probably listening to what your brain told you to eat rather than what your gut was trying to tell you that led you to gain weight in the first place. We are going to note a few key brain areas and functions that are
relevant to appetite retraining here.
1. The hypothalamus
This thermostat-like centre helps us regulate our basic bodily functions to allow us to maintain a state of equilibrium (homeostasis). When these functions, such as blood glucose level, temperature and hydration, move out of the comfortable range, bodily and mental systems are set in motion to restore harmony.
For example, if your temperature is rising, your pores will open and sweating will help to cool you. If the temperature continues to rise, signals to your conscious brain tell it to take action to cool down by, for example, opening a window or taking off a sweater.
Eating is partly regulated by the hypothalamus, which is helpful to keep our eating regulated and our weight constant. However, it’s also strongly influenced by two other systems: the pleasure system and the anxiety system.
2. The pleasure system and hedonic overeating
The areas of the brain (the cortico-limbic structures) involved in processing pleasure are involved in the anticipation of eating and particularly in eating certain types of food. Your favourite treats are at the top of this list, so now we’re in the realm not just of satisfying the body’s need for sustenance, but the brain’s desire for stimulation of its pleasure centres.
The big food corporations are ahead of us here as they have worked out what particular flavour and texture combinations, in what sequence, push our pleasure buttons most exquisitely, by releasing a cascade of flavours and textures that blow us away.
Those foods are manufactured to be what Dr David Kessler calls ‘hyper-palatable’. The pleasure centres are governed by positive feedback loops that trigger us to desire more as we eat, not less.
This system reacts to the amount of reward rather than the amount of energy in the food, and each time we experience pleasure, our brain stores the information under ‘things to do again, and soon!’
We’ll look at how to include these foods in the overall range of what you eat, without allowing them to overwhelm your pleasure system so that you are unable to stop eating them. You probably have no problem stopping eating your favourite vegetable, but your favourite treat?
That’s another story. Not everyone develops cravings because we all have different levels of response to pleasurable cues. If you’re someone who does struggle to resist overeating certain foods, for advice on how to reduce cravings.
3. The limbic system: anxiety, stress and emotional eating
Anxiety and fear are the body’s way of helping us deal with danger. The brain centre that is involved in detecting such threats is the amygdala, part of the limbic system. When a threat is detected, the amygdala triggers the release of adrenaline from the adrenal glands to help deal with the danger. In this “fight or flight” state, our heart rate surges to pump oxygen to our muscles.
Extreme hunger is, of course, dangerous, and will trigger the fear response, but many of us with plenty to eat have developed a fear of even mild hunger, which is not at all dangerous. If you have become anxious about feeling hungry, established techniques for overcoming learned fears will help you.
Stress affects people differently. Some of us eat more when we are stressed and some of us go off our food. Eating more when you’re experiencing a stressful event appears to be related to your background levels of chronic stress, and your biological make-up. Stress affects the areas of the brain that deal with reward, and chronic stress heightens the sensitivity of the reward centre, resulting in an increased appetitive drive.
Your internal clock
We have a number of internal ‘clocks’ that keep time over each 24-hour cycle, in tune with the earth’s rotation. Night and day produce different levels of light, and our bodies adapt to the light/dark cycle of where we live.
If we move rapidly between one daily cycle and another by flying East or West, the resulting jet lag is the consequence of external triggers being out of synch with our internal clocks.
Our appetite-regulating hormones follow a 24-hour pattern, and we come to associate certain times of day or night with eating. These time-triggers are quite powerful for many of us, and you may be aware of itching to eat at around 12.30 pm if that’s when you’re used to having lunch because your appetite system is swinging into action in line with what your internal clocks are saying.
Having regular times to eat works in tune with your body’s daily appetite cycle.
Listening to your gut
As we’ve seen, the digestive system and brain are at work guiding our eating and appetite. We need to use both together, but modern super-stimulating foods, available round the clock cheaply and in abundance, mean that it’s easy to rely more on your brain than your gut.
Too much brain focus is not a good thing if it means ignoring your gut.
When we ignore or override our natural internal hunger and fullness signals, we eat in response to external triggers. We’re more likely to eat things we see and eat beyond the point of being full.
Because we have memories of super-pleasurable foods, those will be the ones we reach for, particularly at times of stress or anxiety. We’re likely to eat until the plate is empty instead of stopping when we’re just full.
We’re not likely to get much pleasure from the food as our taste buds won’t be so sensitive if we’re not hungry, and because we won’t be eating what we have a real appetite for, but what our brain remembers was really pleasurable before.
If we tune in to what our gut is saying, we can gauge when to eat and when to stop. As we’ve seen, we digest and store the nutrients and energy from our last meal and, as we do so, our gut and other organs send increasingly strong signals to our brain to get us to eat again.
As we eat, our stomach wall receptor cells and intestinal hormones send signals to our brain to tell us we’ve had enough. The meal we’ve eaten will be enough to keep us going for a certain amount of time, depending on how much and what we ate.
The Appetite Pendulum
The cyclical pattern of eating and (mini-) fasting suits our biology and means that we don’t have to eat constantly. It’s like a pendulum. My Appetite Pendulum (see below) gives you a way of thinking about your level of hunger or fullness at any point – it is a key part of the Appetite Retraining Programme.
On here and here, I explain how to use the Appetite Pendulum, but for now, just see whether you can gauge where you are on the Appetite Pendulum below right now. The extremes of the scale refer to feeling completely stuffed at one end (+5), which is how you’d feel about half an hour after a very large meal.
At the other end (–5), you’re likely to feel strong sensations in your stomach, perhaps growling or rumbling – this is how you feel when you have missed a meal and it’s now many hours since you ate.
To begin with, some people find it hard to gauge their hunger or fullness levels. If you’re struggling to work out where you are on the Appetite Pendulum, I’ll show you how to use meal-size reduction strategies, while you gradually learn to listen to the hunger and fullness signals from your gut.
That means judging how much you need by looking, so you can still lose weight by training your eye to judge what amounts lead to weight loss and then to maintaining your goal weight.
Appetite retraining is all about learning to eat in tune with your natural hunger and fullness signals. Rather than attempt to do this all at once, we’ll take things one step at a time, partly so that it’s not too much strain on your system to make the change, and partly so that each step becomes easy and automatic – a habit, in other words.
And it’s the fact that you’ll form new eating habits that make the weight loss you achieve easy to sustain.