WHAT HUNGER DOES TO THE BRAIN

Why do we carry on stuffing our faces when we're full? 
How do feelings like sadness, anger and fear affect our appetities?
What happens to the body during a binge-eating session?
We explore the mysterious forces that decide what and how much we eat.

CALORIE JUNKIE

HOW DOES THE FOOD BOSS IN MY HEAD WORK?

Researchers have found that different systems in the brain share a common goal: making sure the person consumes as many calories as they can to provide the brain with as much energy as possible. The body receives calories from carbohydrates, fats and sugar.

However, the more we eat, the greedier the dictator in our skull becomes. Several studies have proven that, as a consequence of this process, food begins to take on a drug-like quality. During meals, overweight people exhibit lower levels of activity in the corpus striatum than people of a healthy weight. This is the area of the brain where the reward substance dopamine is released.

Consequently, obese people need an ever-increasing dose of calories to feel satisfied – just like drug addicts. People of a healthy weight, on the other hand, feel the same sense of satisfaction despite having eaten less.

Excessive eating is rarely out of the news these days. And now a staggering statistic has brought it centre-stage again: according to a study by Dr Roger Gould of the University of California, over 75% of unhealthy overeating is controlled by our emotions. The study, which involved 17,000 participants, seems to suggest that having that extra chocolate bar or second bowl of pasta doesn’t mean we lack willpower or are lazy.

But that’s old nutritional thinking: studies like Gould’s have been revolutionising nutritional science, undermining everything we once believed about body weight and diet. It turns out we primarily eat to gain control of our bad moods and to make ourselves feel good and relaxed for a short while.

WHY WE LIE TO OURSELVES

Science calls this phenomenon ‘emotional eating’. It’s the food we eat without feeling any pangs of hunger. It’s when we snack just after finishing a slap-up meal. It’s the eating regime that makes us gain weight, in spite of our better judgment. After all, we all know the basic rules of a healthy, balanced diet: plenty of fruit and vegetables, whole grains, meat in moderation, sweets only as a rare treat. But feelings of stress – and the desire to make them go away – are strong enough to make us behave in ways that go against our better nature. That’s because our emotions have a powerful ally that knows how to manipulate our behaviour: the brain.

TWO PER CENT OF THE BODY REIGNS SUPREME

Even though it only makes up 2% of the body, the human brain requires 50% of the body’s entire glucose supply to run smoothly. Glucose, a sugar, is the fuel that powers our cells. During stressful situations, the brain needs an astonishing 90% of the sugar we consume. If this stress then becomes a long-term problem, it can have a direct impact on our weight. The brain will always look after itself under all circumstances – it’s selfish. That’s hardly a surprise given that the organ functions as the body’s switchboard and controls all of its processes.

Renowned brain researcher and diabetes expert Dr Achim Peters has been studying the underlying mechanisms of the brain for decades. He has developed the influential “Selfish Brain” theory for a better understanding of obesity: if the organ realises it’s lacking even a small amount of glucose, it sounds an alarm – the “brain pull”. Glucose is immediately delivered to the brain, regardless of the impact this would have on the body’s other organs. Our stress-response system – the most powerful alarm in the body – is also called into action and releases adrenaline.

“We exhibit typical symptoms such as a racing heart, sweating, clammy hands and agitation,” says Dr Peters. We don’t feel right. However, these symptoms quickly subside when the energy deficit is cancelled out. Then the stress responses are dialled down again and we regain our emotional balance. “We enter a stress-free state. Tension subsides and a feeling of wellbeing spreads through us,” says Peters.

HOW CONSTANT STRESS CAN TURN INTO CONSTANT HUNGER

A feeling of wellbeing is exactly what’s missing when a bad mood takes hold. It doesn’t matter if it’s anger or anxiety, negative emotions activate our stress reflexes. In the process, they use the same neurotransmitters as the desire to eat. But another motive comes into play: “Emotions exist to draw our attention to things – to a problem, a conflict that needs to be solved,” says Peters. At the same time, our emotions make us want to change the situation: we want to make ourselves feel better to prevent damage.

Our stress-response system releases the necessary substances to help us achieve that. When we get annoyed about something, our levels of adrenaline skyrocket. The hormone accelerates our heart rate and makes our muscles tense. We clench our fists. We’re ready to take on the cause of the frustration and confront it with all the power at our disposal. At moments like this, we don’t feel any urge to eat. That’s because the body has simultaneously released a large amount of cortisol: the hormone responsible for dialling down all bodily functions – and rebalancing the stress response.

But what happens when we can’t get rid of the anger? What if the cause of the stress sticks around for months? And what if one temper tantrum snowballs and immediately leads to another? In these cases, our stress response remains on constant high alert, meaning we feel tense, unwell and worn down. How do we cope? By eating!

THE DANGEROUS CONSEQUENCES OF COMFORT EATING

As soon as the brain receives a quick glucose boost, it stops trying to secure energy. In the short term it calms our stress response right down. “Comfort eating isn’t the best solution but it’s the most convenient: it makes you feel better in the blink of an eye, hence the name,” explains Dr Peters. The problem is that comfort, or “binge”, eating – when a person wolfs down large quantities of sweet or salty snacks in a short space of time – calms our body’s systems, but it doesn’t remedy the actual, crucial, cause of our emotions. Comfort eating is a quick fix and, in the long term, masks the real problem – which continues to eat away at us. And so we find ourselves reaching for a chocolate bar or bag of crisps again every time the negative feelings resurface.

This has repercussions for the brain: the unsolved, lingering conflict repeatedly puts our stress response on red alert and can cause serious damage – our brain pull is continuously weakened. The stress response is placed under permanent pressure and becomes worn down. “Internal emergencies don’t just make us unhappy and dissatisfied, they also have a massive effect on the way the body metabolises energy,” says Peters.

A weak brain pull means that the brain can no longer rely on the body’s energy reserves – it must get all of the glucose it needs directly from the food we consume. What’s more, the brain loses the ability to influence the body’s processes because it becomes so preoccupied with finding glucose. As a result, energy is drawn out of fat and muscle tissues and stored.

In a nutshell, we need to eat more to satisfy the brain – a lot more, far more than we actually need. The end result? We put on weight and a vicious circle of being emotionally overwhelmed and stressed leads to comfort eating.

HOW DO YOU OVERTHROW THE HUNGRY TYRANT IN YOUR HEAD?

There’s only one way to break this cycle: “Because energy and emotional balance are inextricably linked, a balanced emotional state is the only crucial step you can take to normalise your brain pull,” explains Peter s. Confused? Simply put, it means that we don’t need to sort out our eating habits in order to lose weight – but gain control of our feelings instead.

That may sound quite simple, but for many people it presents a considerable challenge. To properly deal with our feelings, it’s important that we can clearly differentiate between them. An American study showed that participants who were able to tell their emotions apart from one another exhibited a much higher level of emotional knowledge. It meant that they could correctly weigh up the significance of a situation and, as a result, were able to react appropriately to problems.

The scientists also discovered that people who perceived their emotions as a jumble of thoughts did exactly the opposite: it was incredibly hard for them to exploit their feelings as carriers of information – or see them as helpful in evaluating a situation properly. Accordingly, this set of subjects also found it more difficult to think of ways they could react to change the feelings.

The American psychologist Dr Jennifer Taitz, author of the book End Emotional Eating, argues: “Treatment for a sinus infection is different from treatment for the stomach flu. Similarly, the way you navigate loneliness differs from the way you would manage anger – not least because emotions convey important information, and the message of loneliness is very different to the message of anger.” Her conclusion: “Learning to sit with emotions and overcome emotional eating may provide an experience of mastery, or real accomplishment, trumping the short-lived pleasure we notice when we indulge.”

TYPES OF STRESS

WHY ARE SOME PEOPLE CONSTANTLY HUNGRY?

When we feel under stress, the brain releases the neurotransmitter cortisol. The hormone flows into the blood from the adrenal glands and spreads around the body, causing various things to happen. Initially, it calms us down. However, when we’re stressed we need a lot of cortisol – and demand can outstrip supply. What does our brain do if this happens? In people with the more relaxed Type B personalities, it demands more energy: feelings of hunger intensify – and the person gains weight. This balances their mood.

People with the more competitive Type A personalities, on the other hand, don’t experience these pangs of hunger. They tend to be slimmer, but they’re also more stressed and have a raised cortisol level – and this increases the risk of dying from a heart attack. Furthermore, studies have proven that overweight patients actually have a greater chance of surviving heart attacks, kidney failure and stroke than their more slender counterparts.

10 QUESTIONS ABOUT THE HUNGRY BRAIN

1- WHAT’S THE DIFFERENCE BETWEEN STARVATION AND A DIET?

From the brain’s perspective every food shortage, be it a voluntary weight loss programme or actual starvation, is treated like an energy crisis. In both instances, the brain implements emergency measures: it activates stress responses to make us search for food.

2. WHY DO DIETS MAKE OUR SKIN AGE FASTER?

When you reduce your calorie intake, you’re robbing your brain of energy. The brain declares a state of emergency to prevent this – and the level of cortisol in the body increases. The result? Fatty tissue is drawn out from areas such as the face and stored as abdominal fat. Cortisol also accelerates the ageing of skin and connective tissues.

3. CAN A BLOOD TEST REVEAL IF WE’RE LIKELY TO BECOME FAT?

Normally, the brain draws energy from its reserves in the body (fat, muscles). If the ability to do this (known as ‘competent brain pull’) is disturbed, the brain is starved of energy. It becomes more dependent on the energy that circulates as glucose in the blood and demands more and more food. Overweight people suffer from a lack of energy, even though their bodily reserves are fully stocked – their brains have lost the key to opening these reserves.

4. WHY DO OVERWEIGHT PEOPLE KEEP EATING, EVEN THOUGH THEIR BODY HAS ENOUGH STORED ENERGY?

Normally, the brain draws energy from its reserves in the body (fat, muscles). If the ability to do this (known as ‘competent brain pull’) is disturbed, the brain is starved of energy. It becomes more dependent on the energy that circulates as glucose in the blood and demands more and more food. Overweight people suffer from a lack of energy, even though their bodily reserves are fully stocked – their brains have lost the key to opening these reserves.

5. WHAT HAPPENS TO MY BRAIN WHEN I GO ON A DIET?

The brain’s stress response is activated during an energy crisis, such as a diet. During a diet, the brain’s stress response can’t return to its normal mode, meaning that the cortisol level is continually raised. Too much cortisol can cause our connective tissue to age and leads to severe mood swings – even depression. Moreover, the brain and its stress reflex can’t get used to the diet mode. Physiologically, it’s simply impossible because the energy requirements of the brain can’t be altered. It’s like thinking you can reduce the fuel consumption of a car simply by filling it up with less petrol.

6. WHY DO WE WAKE UP IN THE NIGHT FEELING HUNGRY?

If this happens, it’s highly likely that a lack of energy is to blame. Usually, the brain’s energy demands are up to 40% lower at night. That’s why we normally don’t experience feelings of hunger while we sleep. However, if we wake up feeling ravenous, the body’s fat reserves are clearly no longer sufficient to provide the brain with enough energy during the night.

7. LESS FOOD = LOWER SEX DRIVE?

Diets that impact on our energy levels force the brain to act. They divert just enough energy without causing a crisis, but the body must compensate. It dials down all of its systems that aren’t vital to survival: concentration decreases and you get tired more easily. Another symptom of dieting can be a lower sex drive.

8. DOES THE BRAIN’S ENERGY SUPPLY DECIDE WHETHER YOU’LL BECOME A SUCCESSFUL ATHLETE?

Dreaming of becoming a medal-winning marathon runner? Key to your success is how well your brain can control your energy supply during a race. You can train for this metabolic work in the same way muscles can be built – and it has a significant effect on your own performance capacity and sporting success.

9. IS OBESITY REALLY A DISEASE?

If the brain pull is no longer working, the organ needs a plan B to get enough energy. Rather than taking glucose primarily from the body’s fat reserves, it gets it directly from the blood when the blood’s sugar levels have been raised after a meal. This is an example of the brain’s ability to problem-solve to reverse an energy emergency. However, a side effect of this ingenious solution is that the person gains weight. If you try to burn off this extra weight by dieting, the brain spirals into a new energy crisis – which can also have dramatic consequences.

10. WHY DO ALL OF THE INTERNAL ORGANS SHRINK DURING A DIET – APART FROM THE BRAIN?

Researchers have shown that going on a diet causes internal organs, such as the heart, liver and kidneys, to get thinner – with the exception of the brain. Why? Because it provides for itself first. In contrast to the other organs, the shrinking process would inflict irreversible damage to the brain.

Published in "World of Knowledge" Australia, issue 44 October 2016, excerpts pp.36-43. Adapted and illustrated to be posted by Leopoldo Costa.

Share this post