The Three Types of Hunger

Adam Mansbach said ‘Eating is one the great pleasures of life’. My grandmother takes that one step further with ‘There is no greater pleasure in life than that of eating.’ But how does it all actually work? What makes us want to eat and why does it feel so good?

This article explores the three different types of hunger and how we can work better with them to maintain healthy body weight, more energy and overall improved quality of life.

1. Brain Hunger

One of the primary roles of our brain is to regulate balance, homeostasis, in the body. And body weight is included in that. The brain is constantly making sure that the body has just enough energy storage in case a famine is around the corner. Fat cells in the body produce a hormone called leptin, also known as the satiety hormone. Leptin levels don’t change in direct response to a single meal, but rather as a trend of eating over time. When a person gains weight, leptin levels increase due to the increase in body fat, and conversely when a person loses weight, leptin levels fall. High leptin levels signal to the hypothalamus in the brain that you have enough energy stores, so the brain doesn’t need to drive you to seek out food. But after weight loss, lower leptin levels are interpreted by the brain as ‘threat of starvation imminent, seek out food now!’ This is brain hunger.

Most obese people develop a condition called leptin resistance. They have ample fat cells producing very large amounts of leptin. But for reasons not yet fully understood, the high level of leptin isn’t doing its thing. The signal is broken, satiety isn’t achieved and the obese person continues to eat despite adequate energy stores. Leptin therapy has been tried in obese people but doesn’t seem to have the effects you’d expect of suppressing appetite.

On the other end of the spectrum, brain hunger triggered by weight loss and low leptin levels, is one of the key reasons why short-term diets don’t work. Several studies have shown that most people regain the weight they lose during a diet with up to 40% gaining back more weight than they had originally lost! The brain is always working to protect us against starvation. Very low-calorie or super restrictive diets put the brain into survival mode. And when the diet is over, your brain is still left with the side effect of those limited calories – a fear of famine striking again. And now that food is available again, your brain thinks it is very smart to stock up and store as much as possible, similar to the panic buying we’ve seen in various stages of the COVID pandemic!

2. Stomach Hunger

The upper part of the stomach contains specialized cells that produce ghrelin, the hunger hormone. Ghrelin is also made by the small gut, pancreas and brain, but in much smaller quantities.

Unlike leptin, ghrelin levels fluctuate daily in response to how much or how little you eat. When your stomach is empty, ghrelin is produced which makes you feel hungry. But as the stomach is filled, the stretching of the stomach wall causes the specialized cells to stop making ghrelin. Falling ghrelin levels give you the signal that you are getting full. In the short term, anything that stretches the stomach will make you feel fuller and therefore less hungry. This is the science behind why water before or with a meal is recommended for people trying to eat less. This is also why eating foods that are harder to digest (like lean proteins, healthy fats, whole grain unprocessed carbohydrates and fibre) helps you feel fuller for longer. 

Adults have roughly the same size stomach regardless of their body weight. So even though the stomach stretches with eating, it returns back to its usual empty size after digestion. The average adult stomach can stretch to hold about one litre of contents. However, in obesity, frequent overeating makes the stomach get accustomed to overstretching beyond this, at extremes holding up to 3.5 litres of contents! Frequent over distension of the stomach may interfere with the way ghrelin works.

3. Sensory Hunger

Humans are hardwired to want to eat just by smelling, seeing or talking about food! Our brain evolved when food was much scarcer than it is now, but we’re still driven towards consumption whenever food is accessible. Stimulation of our senses by food causes an increase in pleasure chemicals like dopamine and serotonin in our brain. The levels of these chemicals shoot up when we actually begin the business of eating. When these feel-good neurotransmitters are released, our brains makes us repeat behaviours to re-create that pleasure.

A perfect example is the aroma of a delicious meal. This too can make us feel hungry, even when our body doesn’t physically require any additional energy. Just think of how there’s ‘always room for dessert.’ We know that the brain stimulates our sense of smell at times of hunger to help us find food. On the other hand, wanting to eat a slice of a freshly baked cake just because it smells so good, is a learned response. The brain remembers the past association of that particular scent with yumminess. It’s not fully understood exactly how smell and hunger interplay with one another. But who hasn’t experienced the salivation and trigger of hunger that comes from smelling something delicious?

The world’s best chefs know that making a plate of food look beautiful is as important as the ingredients. There are hundreds of culinary courses dedicated to the subject of ‘plating’. The sight of a beautifully crafted and colourful plate is akin to an art. Humans clearly love looking at food! Just look at the number of tv channels dedicated purely to cooking, or the size of the cookery section in your bookstore.

A meal with lots of different textures from crunchiness to chewiness to smoothness and more can trigger hunger. The sensory pleasure from having a small taste of texture can make you feel like you want more. Not because you are actually hungry, but because it feels so good to crunch those potato chips in your mouth or sink your teeth into a soft, doughy, pillowy bread roll. But different textures can also help to satisfy you.

Taste is arguably the most important determinant in food choice. Studies have shown that the sensory pleasure derived from the flavour and taste of food significantly impacts the amount of food we eat. We all hear that having a diet with variety is healthy. But a number of studies have shown that too much dietary diversity makes it harder for us to control our behaviours around food. If there is more variety of flavour and taste, the more we will consume, especially when it comes to processed and packaged foods. Salt, sugar, fat and artificial flavourings all flood your brain with dopamine kicking in the desire for more. The classic example is the buffet. An over load of choice leads to overloading of our plates.

3 easy tips to hack sensory hunger:

1. Keep just one type of treat food in the house rather than a variety of options which will lead to over indulgence. For example instead of two types of cookies, a variety of chocolate or 3 different flavours of ice cream, just buy one type.

2. Make it harder for yourself to have seconds by limiting availability of food. When food is more readily available, we tend to eat more. An example of a social experiment that showed this really well involved inviting strangers on the street to attend a free music event at a pub in London. The participants didn’t know they were part of an experiment. As they attended the event, they were secretly divided into two categories. Group 1 were given a single plate of chicken wings to eat during the event. Group 2 kept having their empty plates of chicken wings replenished without the participants placing an order for more food. The findings were that Group 2 just kept on eating, polishing off plate after plate!

3. Add texture to your meals to make them more satisfying with a sprinkling of nuts.

If you have anything you want to ask, or if there’s a topic you’d like me to write about just let me know.

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