The Only Way to Successfully Fight Obesity is Through Education
With global obesity on the rise, everyone is pointing fingers, shifting the blame toward the food industry. It’s true that we live in a society where we are constantly bombarded with food cues, an endless fireworks display reminding us that there is something to eat everywhere we look. However, as researchers from the University of Cambridge and Louisiana State University point out, controlling what we eat may actually have more to do with the neurocognitive processing of food reward.
The obesity epidemic is built upon a foundation of poor education surrounding how our brain perceives food. Due to the overlapping and integrated nature of our liking and wanting systems, we are always vulnerable to persuasion. We can easily be convinced to keep on eating, even when we don’t physiologically need food at all. But it doesn’t end there. Eating calorie-dense foods only compounds the problem, sending us deeper into the abyss of our evolutionary cognition. Due to their satiating nature, high-sugar and high-fat foods have the potential to raise our feeding reward threshold. Ultimately, this means that nutrient-rich low-calorie foods, including many fruits and vegetables, can no longer satiate us in the same way, decreasing our incentive to eat them.
Rather than wasting our time with the obesity blame game, we need to start fighting this global epidemic through education. By understanding the neurocognitive correlates of feeding behaviour and exploring the disharmony between current dietary trends and our evolutionary instincts toward food, we may come to appreciate a sustainable way of eating in modern society.
Food Across the Ages
Over the course of evolutionary history, meeting energy demands has been at the forefront of survival. Every species on the planet has developed its own unique set of tools for sourcing food, monitoring nutritional status and adapting to ever-changing environmental conditions. While we, as humans, do not possess the stealth of great hunters or the sight and smell of crafty foragers, we do claim the greatest weapon of all, our brain.
From humble hunter-gatherer origins, the human brain reshaped the planet, giving rise to a species that was no longer required to live off the fruit that earth provided. Instead, we found a way to make the earth work for us. And thus, agricultural settlements started to spread around the world. A few thousand years later, we sit at the top of a food chain of our own making, a network of mass agriculture, international trade and food surplus. We have complete control over our food supply and our next meal is no further away than a trip to the local supermarket. However, while finding our next meal is no longer the challenge it once was in our evolutionary past, the cognitive processes surrounding feeding behaviour are still very much unchanged.
We are no longer fearful of food being in short supply, but rather, we find ourselves concerned with a global obesity epidemic fueled by an immoderate consumption of calories. For the first time, a species has become so dominant that it lives in excess and must find ways to silence its innate desire to eat in order to stay healthy. Obesity has arisen from our ancient mind-set being carried through to the modern world.
Consciousness & Food
While it may seem belittling to think that our behaviour is merely the sum of chemical reactions in our brain, it may be just as grandiose to believe that we have complete control over all the choices we make. The discussion about human autonomy and free will extends, in an equally polarising manner, to our food choices. The assumption in our society is that we are entirely free to eat as we chose. However, when we explore the neural correlates of food reward, the foundations of this belief appear a little shaky.
We certainly devote a great deal of brain power to feeding every day, with each of us, on average, making an estimated 200–250 food decisions. Yet, much of the cognitive processing involved in these decisions is subconscious, arising from highly conserved brain regions in a seemingly autonomic manner. In other words, when there’s food on the table, our hands hypnotically reach out for the snack bowl without much thought involved at all.
Left to its own devices, our “animal brain” would feed us indefinitely, failing to see our behaviours in the context of the world around us. It’s only when our “human brain” kicks in that we can exhibit some form of cognitive control.
There seems to be an ongoing battle in our head between our instinctive desire to eat more and our conscious acknowledgement that there will always be food on the table. In spite of the hormonal signalling and rapidly firing neuronal networks that are telling us to eat, we have a peculiar capacity for top-down control over our feeding behaviour. For this reason, we can actively choose to be vegan, or restrict our carbohydrate intake, or even choose to not eat at all. Understanding this uniquely human trait may hold the key to promoting weight loss at the population level.
Exploring The “Animal” Brain: Physiological Hunger
At the very core of energy balance and weight control is a specialised region of the brain called the hypothalamus. It is a highly conserved brain region that functions in a similar manner across the animal kingdom. In fact, overstimulation or damage to this part of the brain can have dire consequences. At one extreme, overstimulation of the hypothalamus favours a voracious appetite, excessive eating and weight gain. At the other extreme, damage to the hypothalamus results in the destruction of appetite, the cessation of eating and, ultimately, starvation.
The hypothalamus, however, does not act in isolation. It integrates incoming nutritional status and hormonal signals from the body with reward pathways, memory systems and conscious processes in the brain.
In particular, the hypothalamus coordinates with the brainstem, another primitive brain region that possesses all the essential machinery to monitor nutritional status in the body and regulate the ingestion, digestion and absorption of food. Together, the brainstem and hypothalamus respond directly to physiological hunger, forming a system that can motivate feeding as nutrients become deplenished. However, alone, they lack the sophistication to carry out reward-based decision making or to form anticipatory responses in a changing external environment. These higher behaviours depend on feedback from other parts of the brain.
Exploring The “Animal” Brain: Food Reward
While food no longer feels like a selective pressure for survival, our brain cannot escape its evolutionary past. Biologically speaking, the longer we go without food, the better it tastes. Food has evolved to be incredibly rewarding, particularly when we are nutrient deprived. This effect can be largely attributed to the mesolimbic dopamine reward pathway in the brain. As the time since our last meal increases, so does the incentive to eat, the subjective experience of satisfaction caused by the release of dopamine.
This primal reward pathway is responsible for positive reinforcement, a process that favours a behaviour being repeated in the future. Indeed, this is very much the case when it comes to eating. We are driven to eat because it feels good by biological design. From an evolutionary standpoint, this makes perfect sense as sourcing and consuming nutritious food is critical to our survival.
The hypothalamus, brainstem and mesolimbic system give rise to our want for food. However, we don’t only eat because we need to. We have evolved to eat whenever food is available, presumably, so that we can store energy away for later use. As such, elaborate systems have also evolved to help us select the most valuable foods.
Exploring The Human Brain: Homeostatic & Hedonic Eating
With food being so readily available today, our experience of hunger is very different to that of our ancestors. It is highly plausible that, often, our want for food is not driven by physiological hunger, but rather, higher cognitive processes pertaining to food reward. Being aware of this concept in a calorie-dense world is essential if we hope to regain control over what we eat and give ourselves the best chance at curbing global obesity.
Unlike our want for food, which grows stronger as we await our next meal, liking food is not correlated with nutritional status. How much we like a certain food is determined by our past experiences with it. It is like a memory of how a food looks and tastes, how it satiated us, its nutritional and physiological effects, the social environment in which we ate it and our emotional state after we finished it.
Liking food may be either a conscious or subconscious process. In either case, the neural networks that contain our liking memories feed back into the primitive brain areas that regulate our appetite and motivation to eat.
This well-studied interconnectedness of our liking and wanting systems means that we can experience hunger even when our body doesn’t necessarily need food. The simple thought of french fries gives rise to the idea of their crunchiness, their saltiness and the nearest fast-food restaurant. It reminds you of how they taste and how good you feel when you eat them. The next thing you know, you have just ordered them at the drive-through.
The point is that your subjective experience of hunger is not necessarily driven by a need for food but can also be inspired by the subconscious processes responsible for liking food. When you compound this idea with an environment that is relentlessly priming our brain to think about the foods we like, it brings into question how much control we really have over our diet and whether we need to actively suppress our instincts in order to experience true hunger.
What’s really interesting is that most of us already know that a food can be liked but not wanted. For example, following a savoury dinner, we usually don’t feel like eating more salty food. In this case, as our desire for certain foods is met, our brain devalues the reward associated with those foods. However, this doesn’t mean we no longer like those foods, it’s just that our brain has temporarily reduced our incentive to eat them. Cognitive neuroscientists term these processes “go systems,” meaning that while food reward can decrease upon satiation, it can not be entirely switched off.
The way our brain responds to food gets even more fascinating after a meal. We’ve all experienced sensory-specific satiation, whereby, even after having finished our savoury dinner there always seems to be room for a sweet dessert. Despite not needing food for sustenance, your instincts don’t tell you to stop. In this case, the motivation and reward for eating salty foods decreases throughout dinner but the incentive for eating sweet foods remains high.
The Great Obesity Battle
While in our evolutionary past choosing the most rewarding foods always made sense, our “animal” brain is not fully prepared to process the calorie bombs of today. However, despite all our instincts working against us, we still have the potential for cognitive control, a higher process that tests the limits of our “human” brain.
We now understand that feeding is a far more complex behaviour than it appears on the surface. It is an integrative multisensory experience that begins well before you’ve taken the first bite of a meal and lasts hours beyond when you’ve finished eating. We also possess a wealth of knowledge surrounding human nutrition, thanks to advancements in biochemistry and food science. We can even count the calories and micronutrients that go into our body, providing us with cognitive guidance regarding what our body needs. And now, we have reached a point where we understand the difference between hedonic eating (for pleasure) and homeostatic eating (for sustenance).
Though our “animal” brain will never break free of its evolutionary origins, in order to combat obesity we need to exercise our unique capacity for top-down cognitive control when it comes to our diet. Many of us already partake in religious fasting, foregoing food for hours on end. Others apply cognitive control by selectively consuming ethically sourced foods. We all have it inside us. But, first and foremost, we need to better educate the world that in modern society our want for food is often driven by our like for it, but very rarely by our need for it. Experiencing the difference will go a long way in our journey to regaining control over our energy balance, appetite and body composition.