Why Your Body Demands Certain Foods
When we’re hungry, food begins to dominate our thoughts. Just the sight or smell of food makes us salivate in anticipation of a delicious taste, like one of Pavlov’s dogs. But sometimes we only want a single food or continue to eat it, even when we’re not hungry. Certain foods create cravings and fire up our desire, doing so at a molecular and cellular level, directly affecting our brains. Below we’ll investigate our yearning for four different foods, as examples of the biological and food chemistry factors surrounding cravings.
Chocolate has chemicals that trigger your brain’s pleasure center. Roasted cacao beans (the origin of chocolate) contain many volatile aroma-bearing compounds. Our nasal chemical receptors pick up those compounds, the combination of which becomes one delicious comforting smell. The message sent by our olfactory receptors influence the taste of chocolate, but two other important components really draw us to it.
Half of chocolate’s calories come from fat (provided by cocoa butter). The scarcity of food in human evolution caused us to feel delight when eating this energy-rich source of life-saving fuel. The silky mouthfeel of fats and oils play a large part on our perception of pleasure, but the core is what happens in the brain. Consuming fatty foods lights up activity in our lateral hypothalamus and amygdala, like an amusement park control board switched on. Since the amygdala is responsible for our emotional response to food, we fondly recall the pleasure from eating fat.
Chocolate also has sugar which supercharges the effect on our pleasure perception, seducing us further and driving our brains wild. Sugar is the most rapidly used and simplest form of carbohydrate, the primary source of energy for our bodies. Chocolate’s 50/50 combo of sugar and fat mirrors the only natural food with this ratio — mother’s milk, our life-sustaining nourishment at birth. So, it seems we biologically crave chocolate! Desserts such as cheesecake, rich cookies, ice cream and donuts with this half and half split trigger our desire to consume them.
The daily ritual of brewing and pouring a cup o’ Joe draws us to drink coffee with each breakfast, but it isn’t the only thing doing so. Java can magnify the desire to repeat eating something, partially due to its caffeine which boosts the reward pathway. Caffeine makes the pleasure more intense by assisting the nucleus accumben’s release of dopamine, thus amplifying the reward we feel. This neuropharmacological mechanism also explains why caffeine is potentially addictive.
As a stimulant, caffeine’s effect on our energy and alertness is somewhat akin to that from amphetamine and cocaine. Some people don’t just want more coffee, they need more coffee. Regular coffee drinkers can build up a tolerance to caffeine, requiring more heavy consumption to reach a caffeine hit. Caffeine addiction is real enough that some health care professionals consider caffeine dependence a clinical disorder!
If you’re a spicy food lover, there’s a biochemical reason for that, too. The intense heat from chili peppers is provided by capsaicin molecules which hit very particular receptors in our mouth and body, causing a fiery sensation. Such pain signals are supposed to protect us from edible fire, yet some people enjoy the burn.
The body’s flight-or-fight response of releasing adrenaline (accompanied by rapid breathing, sweating and quickened heartbeat) is also followed by a pain-relieving endorphin rush. It’s this physiological reaction of releasing a feel good happy hormone that becomes addictive, like from opiate drugs or thrill rides. We seek that rush and exciting sensation… and know just where to find it.
Alcoholic beverages (beer, wine and distilled spirits) from the fermentation of a variety of grain or fruit all contain ethanol molecules. These are small enough to pass right through the membrane protecting our brain. When alcohol crosses the blood-brain barrier it affects one neurotransmitter in particular, dampening brain activity, initially lowering our inhibitions and providing an initial sense of amusement. These positive feelings are what many social drinkers strive to achieve in their buzz, time and time again.
Too much acute alcohol consumption and the brain’s emotional, motor control and memory regions are suppressed.
This is Why We Crave
Foods such as these can release flavors that create a sensory overload causing us to crave them over and over again. They stimulate the amygdala which triggers the reward pathway, primarily from the nucleus accumbens. This desire center creates our drive to eat the same thing again. Our hippocampus records the pleasurable occasion as a strong memory, so we anticipate the same response from the same foods. In our frontal cortex, we remember the pattern of behaviors and choices needed to obtain the treat so we can recall how to get it again in the future.
Wow. Now it makes sense why it only takes a sight, smell, touch or mention of the desirable item to remind us that we enjoyed it and presto – we want some again now! It’s how you answer a craving that impacts your long-term eating habits, body composition and weight.
Ready for more great articles from our dietitian? Subscribe to our newsletter to get all the best highlights from our blog, right in your inbox!
Mark Williams (Edit Producer) (2017). Food on the Brain [Video series episode] in Gideon Bradshaw (Series Producer), Food: Delicious Science. England: BBC. https://www.pbs.org/food/shows/food-delicious-science/
Meredith, SE, et al. Caffeine Use Disorder: A Comprehensive Review and Research Agenda. Journal of Caffeine Research. 2013; 3(3), 114–130. doi:10.1089/jcr.2013.0016 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3777290/