Food Cravings: How Biochemical Mechanisms May Be the Real Problem
Would you believe your inability to lose weight has nothing to do with willpower? Would you believe your food choices are controlled by mechanisms within your hedonic brain?
How Cravings are Controlled by Biochemical Mechanisms
You see, humans evolved in an environment of food scarcity. It is ingrained within each one of us to seek out the most nutrient dense, satisfying foods and eat more than our energy needs require. We actually have built-in biological mechanisms that cause us to seek out high-density nutrient rich foods to help us survive periods of starvation. After all, hunter-gatherers often experienced stretches of time where no food was available. In order to survive, they would naturally be drawn to nutrient dense, satisfying food. And when food was abundant, they could eat more than required.
The same mechanism that kept humans alive for centuries has become a real problem in today’s modern society, because highly rewarding food is now everywhere! We no longer have to hunt and scour to obtain it like our ancestors did. Instead, we can find it around every corner - in grocery stores, big box stores, and gas stations alike.
We have evolved from eating the nutrient-dense, low calorie and anti-inflammatory foods that our ancestors ate - predominantly fruits and vegetables, to a diet of calorie dense, rewarding foods.
Fruits and vegetables like our ancestors ate, are also hard to over-eat. Have you ever gorged on too much broccoli? Have you overindulged on a plate of spinach? I didn’t think so.
On the flip side, highly rewarding calorie-dense foods like pizza and cake can easily result in us slouched on the sofa with the top button undone, dazed and in a food coma.
The mechanisms we have in place to keep us alive when food is scarce has actually hijacked our brains.
As a result, we are bound to fail in today’s environment where food is so abundant. To add insult to injury, big food industries hire scientists who understand these mechanisms in order to design foods that are meant to hit all the right circuits. Sugary and fatty foods especially, trick the brain into wanting more and causing uncontrollable cravings.
Why do our mouths salivate at the simple thought of certain foods and why can’t we just say no?
The answer may lie in a powerful physiological driver over which we have little control - referred to as hedonic hunger. The principle of hedonic hunger evolved from a time when hunter-gatherers could override signals of satiety in order to eat more than required, not knowing when their next meal would come.
This may have worked out well for our ancestors, but has proven problematic in modern times. The hedonic properties of food cause us to eat only for pleasure, while certain foods stimulate our need to eat even after energy requirements have been met. This results in us eating more than needed, which easily leads to weight gain and obesity. You may not be surprised, then, to discover that certain foods have a higher hedonic rating than others, leading to our cravings for these foods and our ability to overeat them. (Junk) food has become a drug.
Calorie dense and rewarding foods trigger the reward circuits in our brain and are also very easy to overeat. They push all the right buttons. No wonder we are set up to fail - advertisements for all these delicious foods are also everywhere we turn. Chocolate bars stare at us while we wait in line at the grocery store. Billboards remind us of the foods we enjoyed as a kid, triggering fond memories and make our mouths salivate. Magazines are ripe with photos of the most beautifully prepared dishes that entice us, even through the paper. Smells of sugary waffle cones engulf us as we walk past an old-school ice cream shop leaving us craving one… you get the idea.
Have you ever noticed that some of our strongest memories revolve around food? One of my strongest memories growing up happened every December when it was time to put up and decorate the Christmas tree. My mom always bought a specific box of chocolates (smooth and creamy shell-shaped ones with swirls of milk and white chocolate). We only ever had these “special” chocolates once a year - on the day we gathered as a family to decorate our tree. It became an annual tradition. And to this day, every time I see that same box of chocolates in the store, I am taken back in time. I see myself and my whole family in our humble home. I can hear the festive music playing in the background. I can taste the sweet chocolates and can feel the creamy texture. I enjoy one in my mind and relive those blissful days of my youth. This is not surprising as hormones and memories create Pavlovian responses. Sensory cues can trigger thoughts, memories, emotions, fears, and even cravings for food.
Our cravings are also related to the reward centre in our brains - the hedonic hot spots in the brain that cause ravenous cravings for certain foods even though our stomachs have reached capacity. Which foods are they? You may wonder.
Among the Most Addictive Foods (according to HealthLine.com) are chocolate, chips, baked goods, ice cream, sugary soda, fried chicken and buttered popcorn. Topping the list, not surprisingly, is pizza. Notice how these are all processed foods, predominantly high in sugar, trans fat, or both?
Also not surprisingly, the least addicting foods are whole, unrefined foods. At the top of this list? Cucumbers!
What would you rather… a slice of pizza or a cucumber?
The 11 Least Addictive Foods
Cucumbers
Carrots
Beans (no sauce)
Brown rice
Broccoli
Bananas
Salmon
Corn (no butter or salt)
Strawberries
Granola bar
Water
Though we inherently know which foods are good for us and which are not, it’s not enough to be armed with this knowledge. Our limbic system is pre-programmed to crave highly rewarding foods to satiate us during times of starvation. Our inability to say ‘no’ to their tempestuous nature and walk away has little to do with will power or self-control. It’s made extremely difficult by the limbic system, or hedonic brain, which drives our food preferences. This system operates on a deeper level - a level below that of conscious thought, pushing us, and driving us, even if don’t want to listen. Advertising companies also know and understand these driving forces that cause us to continually reach for the sugary soda or pull up to the drive-trough window, as the advertisements for food themselves, trigger our reward systems.
“Over time, humans and animals do not simply experience rewards: they anticipate them”.
-Pub Med Pub Med [PMCID: PMC4477694]
Similarly, excitatory neurotoxins or “excitotoxins” may be at play. These are non-essential amino acids that excite our taste buds and make foods taste more flavourful than they actually are while prompting us to keep eating even after we are full. Not surprisingly then, they are abundant in processed foods and restaurant meals - which helps explain why a stir fry or plate of veggies tastes better at a restaurant (and I used to think it had something to do with the fact that I didn’t have to make them).
Because excitotoxins can destroy neurons in our brains, they should be considered dangerous and avoided in large amounts. Some common, yet dangerous excitotoxins include MSG, aspartate, domoic acid, glutamate, and L-BOAA.
What else might be preventing us from making the healthier choices we know we should be making? The microbes living in our guts!
How Our Micro-biome Affects Cravings
Something happens when our gut micro-biome changes. When we eat a lot of sugar, the microbes living in our gut thrive, and demand more. Sugar is what they feed on. You may also know that sugar has addictive properties and that the physiological cravings for sugar are difficult to pinpoint or explain. It’s not like an ache or pain, but more of a feeling. That feeling or urge comes on unexpectedly and nags us until we are forced to listen.
What causes such strong cravings? The billions of tiny ancient microbes we have living in our guts! That’s right - the number of microbes we have residing in our bodies far out number the amount of human cells we have. They are ancient, having existed much longer than humans themselves, and feast on the sugars we provide. In fact, we humans are the evolutionary tool that was designed to serve as the host in which these micro-organisms live!
At long last, we are finally starting to gain an understanding of the importance of this microbial community within each one of us. Moreover, it is the health of our gut microbes that more often than not dictate the health our own bodies and our behaviour, as well.
That’s right - the microbes within our gut affect our health and behaviour!
Case in point: a little parasite called toxoplasma gondii. This parasite changes the behaviour of mice in a way that increases the parasite’s chance of entering a cat in order to complete its life cycle. The parasite lives and reproduces in the cat’s brain. Humans can also be infected by this parasite. Though most people have strong enough immune systems to prevent the parasite from causing problems, it is advised that pregnant women avoid cleaning a cat’s litter box to prevent accidental exposure.
This is just one example of a tiny microbe that can control behaviour so powerfully - and we have billions of tiny microbes living in our guts. These microbes act in the best interest of the masses - in other words, themselves, and influence their host (yes - that would mean us) in different ways. They affect our moods, depression, ambitions, and every system in the body.
In fact, an overgrowth of bacteria in our small intestines has been linked to many different diseases. Our gut micro-biome produces inflammatory cytokines, and if conditions are right, they escape into the bloodstream through our selectively-permeable gut barrier. This barrier is meant to allow nutrients through and keep certain substances out of our bodies, but when continually bombarded by daily assaults of poor food and lifestyle choices, it breaks down, and becomes less efficient in its protective nature.
Once in the blood, these inflammatory cytokines travel throughout the body and wreck havoc. They have been connected to heart problems depression, diabetes, gluten intolerance, and arthritis.
Yes, even depression may be caused by a disrupted gut micro-biome, as the inflammatory cytokines make their way to the brain. They cross the blood-brian barrier and suppress the activity of the frontal cortex, causing the classic signs and symptoms we recognize as depression.
So not only can our gut bacteria dictate our health and mood, but our hedonic brain acts on our behaviour, driving us to eat for pleasure as opposed to satiety. Armed with the understanding that food cravings, impulses to overindulge, and food addictions are not all your fault, what can we do about it?
Let’s take this same information and make to work for us!
Even understanding that food has hedonic properties and that obesity is a natural reaction to the food environment in which we live can help us make better choices. Which in turn is empowering.
If you feel the urge to eat beyond fullness or have food cravings you would like to take control over, I challenge you to try these 3 tricks over the next week and see what happens.
3 Hacks to Combat Deep-Rooted Food Cravings
Control your personal food environment by keeping highly palatable foods out of the house and out of sight. In other words, don’t keep cookies or highly rewarding snack foods in your desk drawer or pantry.
Anticipate the urge. If you have a long commute and are often tempted to stop for a latte or muffin, leave the house armed with a healthy snack, like some fresh fruit, instead.
Visualize! When strong cravings or urges for certain foods strike, retrain our brain to think about something else… use your working memory (the same part of your brain hijacked by the craving) to conger up an elaborate picture or image in your mind. Picture yourself on the beach enjoying the sun, going for a walk in the woods, anything - other than eating!
You may be surprised how you can use these simple hacks to work for you instead of being a slave to your brain’s desires!
If you do try these hacks, I urge you to leave a comment below and share your experiences.
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