The role of brain signals in your eating habits (and how to regain control).
Forget relying on willpower—it's your brain that drives what, when, and how much you eat. If you’re eating more than you should, here’s how to regain control.
It’s no surprise that obesity rates have risen across industrialised countries over the last three decades. It’s also no secret that people today consume more food than in the past—up by almost 425 calories daily since the early 1980s in America alone. In a European context, data from the World Health Organisation (WHO) and other studies suggest that increased portion sizes, higher consumption of processed foods, and more sedentary lifestyles have contributed to higher calorie intake across many countries, including Ireland.
For years, lack of willpower was cited as the reason, with experts claiming it was down to people not being able to resist overeating. Diet book writers, TV doctors, and nutrition gurus blamed gluten, fats, fructose, or whatever the latest villain was.
Yet, none of this explains why we’re overeating.
Why do we consume so much? Why is it so difficult to stop?
The answer lies in the brain.
Your brain controls your food choices.
Ever opened a bag of crisps planning to have just a few, only to find you’ve eaten the whole thing before you even realised it?
That’s your brain at work.
We like to believe our conscious mind is in charge—"I’ll eat what I want and stop when I choose"—but in reality, our decisions are influenced by complex physiological processes we barely notice.
Behind our conscious decisions are signals from deeper brain regions, hormones, and nutrients like glucose and fatty acids. Most of the time, our conscious mind is simply along for the ride.
In this article, we’ll look at:
how your brain guides your eating habits,
how these biological factors lead to weight gain, and
what steps you can take to take back control.
Why do we decide to eat?
We eat for two main reasons:
Homeostatic eating: Eating to provide the body with energy and maintain balance (homeostasis).
Hedonic eating: Eating for pleasure or to manage emotions.
Most of the time, our meals are a mix of both.
Ghrelin, often called the "hunger hormone", plays a role in stimulating our appetite. It increases before meals and decreases afterwards. Yet, it's not the only factor at play. Studies show that even mice without ghrelin continue to eat normally, suggesting that hunger is influenced by various elements, including:
genetics,
social and environmental cues,
learned behaviour,
our internal body clock (circadian rhythm), and
hormones.
It’s a complex system, and while we don’t yet fully understand it, we do know a lot about what makes us stop eating.
Why do we stop eating?
Stopping after a meal is partly due to satiation—the sensation of fullness that signals the meal’s over.
(‘Satiation’ is often confused with ‘satiety’, but they’re different: satiation refers to feeling full during a meal, while satiety is the feeling of satisfaction between meals.)
Two main physiological factors tell us to stop eating:
Gastric distension: As the stomach stretches, neurons signal to the brain that it’s full.
Hormonal signals: Hormones like CCK and GLP-1 communicate with the brain, telling it to stop eating as nutrients enter the body.
These signals also influence how much we eat later in the day. For example, a protein-rich breakfast can reduce overeating at dinner.
Your brain governs long-term food intake.
What you eat consistently affects your body weight and overall health. A hormone called leptin plays a key role here. Leptin, produced by fat cells, tells the brain how much energy we’ve consumed and stored as fat.
The more body fat we have, the higher our leptin levels, and the brain adjusts hunger and energy use accordingly. When leptin levels drop, the brain activates a set of responses to prevent starvation:
You feel hungrier.
You move less, subconsciously saving energy.
Your metabolic rate slows down, burning fewer calories.
However, this system doesn’t always work perfectly. People vary in how their brains respond to increased leptin levels, which can make maintaining weight harder for some than for others.
How food disrupts your brain’s signals.
Highly processed, hyper-palatable foods—those rich in sugar, fat, and salt—can disrupt leptin's function. These foods make it harder for the brain to receive signals that tell us we’re full, leading to overeating.
Over time, a diet high in these foods can cause leptin resistance, where the brain no longer responds effectively to the hormone. This can make you feel hungry even when you’ve eaten enough.
How to take control of your eating habits:
Here are three steps to help you restore your natural appetite regulation system:
Eat more whole, minimally processed foods: Focus on lean proteins, vegetables, whole grains, and healthy fats. These foods provide nutrients that help regulate hunger and promote fullness.
Eat slowly and mindfully: Slowing down allows your brain and stomach to communicate better, helping you feel satisfied with less food.
Reduce processed food intake: Highly processed foods interfere with your brain’s signals, making it harder to control your appetite.
By consistently following these steps, you’ll likely find it easier to control your cravings, feel fuller for longer, and maintain a healthier relationship with food.
Conclusion:
While physiological processes influence how much we eat, we can make mindful choices to support our brain’s natural systems. Eating whole foods, practising mindfulness, and reducing processed foods can help you regain control over your eating habits, feel more satisfied, and improve your overall health.
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