After we’re done cleaning our houses, we’re inclined to explore and meet new people and go new places in the spring, something that expands and intensifies during the months of summer parties and neighborhood barbecues. As spring develops into summer, our bodies crave more carbohydrate-rich, energy-dense foods. Sugary fruits are naturally plentiful during this period, and our ancestors gorged on them whenever possible. When I think of summer, the hormone that immediately comes to mind is adrenaline, a hormone that’s well known for its role in responding to perceived stress. Adrenaline is useful because it helps us to focus and perform under that stress. And get this: adrenaline is biochemically made from dopamine.22 Dopamine, which gets us jazzed about things to come, is biochemically converted into adrenaline, which helps us perform well and conquer the stressful challenge, however we might define these terms. I find it fascinating and even profound that the symbolic theme for spring (dopamine) is biochemically converted into the symbolic theme for summer (adrenaline). For our ancestors, performing might mean going into battle against a neighboring tribe or hungry predator. For modern man, it might mean summoning the courage to open your business or propose to your long-term partner. Either way, adrenaline is about action and engagement, and summer is all about performance and its subsequent stress.
During the summer, adrenaline courses throughout our bodies because we live in an extended period of stress—all of those late nights, all that stimulation, all the things to do, all that hard work. At this point, you might be thinking, “Hang on, Dallas. Summer is about relaxation and the beach. It’s not stressful.” I’m not talking about stress in a negative, psychological sense. I simply mean demands placed on the body and mind that require cognitive and metabolic resources. No doubt, dopamine and adrenaline both feel good. We even call thrill seekers “adrenaline junkies,” a reference to the addictive properties of these endogenous substances. In fact, stress hormones and endorphins (natural painkillers), and all of the experiential hallmarks of spring and summer, feel so good that we have trouble moving away from them, even when it’s no longer summertime. When we become hyperstimulated and overloaded, then we experience stress in a more negative and costly way. We become stressed out in the popular sense of being overtaxed, frayed, depleted.
The seasonal pivot from summer to fall is crucial and difficult to make. During the fall, fresh fruit supplies naturally dwindle, and the earth produces lower-sugar, starchy root vegetables. With cooler weather and shorter days, we tend to gravitate to heartier, meatier comfort foods. The Thanksgiving table is an ideal representation of what the fall diet is all about. A complete protein is the meal’s centerpiece (the turkey), accompanied by hearty, satiating vegetables like mashed potatoes. There isn’t typically kale salad with strawberries and feta cheese at the Thanksgiving table, unless you’re trying to placate your vegetarian aunt from California. Tender greens and berries are spring fare, and at the Thanksgiving table they would seem out of place, as our bodies at this time of year naturally crave more protein and naturally occurring fats, with less emphasis placed on consuming sugar.
Now if what I said about kale salad in fall was hard to hear, prepare yourself because it gets even harder: this is a normal time to gain a little bit of weight. Think again of the stereotypical overeating we often see at Thanksgiving. It’s conceptually consistent with the spirit of this transitional season, as our bodies are biologically saying, “I have to eat a bunch of calories because the cold winter is coming, and I really should prepare with putting on some extra body fat.” This modest, seasonal weight gain isn’t abnormal or at all damaging. The problem, once again, is when we get stuck in a certain mode and don’t graduate to a different phase that would naturally rebalance the preceding seasons. When I think of autumn, the neurotransmitter that comes to mind is serotonin. Serotonin is associated with reward and pleasure, as well as meaning and gratitude. It’s an adult version of adrenaline—it feels good, but still prompts us to think about the broader picture, about cooperating with others, and about the future. As I’ll explain in more detail in later chapters, serotonin is also associated with leadership, with contribution to the community, and with connectedness to others.
Just like spring and summer, the phases of fall and winter are conceptually related to one another. While, generally speaking, the spring-summer block is largely about moving fast, working hard, and looking out for ourselves, fall and winter are seasons of slowing down, reconnection, and increased intimacy and generosity with the people who matter the most to us. When the winter months arrive, the natural carbohydrate availability recedes even more, and we incline to more dietary fat (with complete protein staying as a pretty consistent feature across all the seasons). This corresponds with a natural reduction in overall physical activity during these cold months, especially those that require large amounts of dietary carbohydrates to support (think hard running or cycling). We all know what comes to mind when we think of winter foods: short ribs, hearty and warming stews, and soup, something that will warm and nourish us after being out in the cold.
When I think of the interpersonal warmth and closeness associated with winter, I think of the hormone oxytocin. Fall’s connectivity, characterized by serotonin, is a fitting precursor to the winter’s oxytocin, a critical neuropeptide (something neurons use to communicate among themselves) that’s crucial for strengthening deep and intimate bonds between people. Oxytocin is released during pregnancy, childbirth, and breastfeeding. It’s been stereotyped as the “love hormone” because it is released during intimate romantic and sexual encounters as well, and even during conversational eye contact, close physical proximity, and nonsexual touch. So it’s less the “love hormone” and more the “bonding hormone,” which allows the broad connectivity of fall to yield to the deeper intimacy, trust, and closeness of winter.
Stuck on Summer
What a beautiful cycle. Our social interactions, activity, sleep, and nutritional inputs harmonize elegantly with the passage of the seasons. But, you probably guessed it, there’s a problem. In the modern world, we’ve become like Kim: stuck on summer. By that I mean we become stuck in a world of (mostly) pleasurable stress. Summer, as we’ve seen, is a great time, both literally and metaphorically. It’s a period of long days and short nights, brimming with activity and stimulation. It’s when the neurochemical stimulation of hormones and neurotransmitters like dopamine lead us to gorge on sugary, carbohydrate-dense fruits. And that’s biologically normal… in the seasonal context.
But following our organization into sedentary civilizations after the agricultural revolution (ca. 10,000 BC), we gradually abandoned any seasonal oscillations, and have had a hard time making the annual pivot to fall-type behavior. Once we started cultivating grain and other agricultural plants, carbohydrate-rich foods became available all year long and eventually formed the backbone of our “civilized” diets. Following the industrial revolution a few hundred years ago, highly processed, high glycemic index, sugary foodstuffs became continually available as well. As I said, it’s normal for us to crave such foods when experiencing the stress of summer. Those cravings are appropriate responses to short-term stressors. Unfortunately, many of us never switch out of summer mode, meaning we live for years or even decades preferring and actually building our entire food system around the carbohydrate-centered diet of summer.
Many of our modern ills arise from our entrenchment in a perpetual summer mode. Take sleep, for example. When we expose ourselves to artificial lights in our office buildings, fluorescent lights in grocery stores, and the blue wavelength lights (such as those emitted by our phone and computer screens) that potently disrupt our normal circadian rhythms, we give our brains the message that it’s daytime, and it’s summertime. The quantity and quality of our sleep both suffer, causing our bodies to crave quick energy in the form of carbohydrates. Yes, disrupted circadian rhythms contribute to sugar cravings. When we’re bathed in disruptive artificial light, especially after the sun has set, it becomes increasingly difficult to hear the deeply intuitive part of our bodies saying, “Hey, it’s wintertime, go for the nourishing beef stew instead of the soda and chocolate muffin you’re eyeing.”
And that drowning out of intuition and satiety signaling leads us directly to overeating and obesity. When our rhythmic ancestors overate sugary fruits and seasonal plants, displacing some dietary fats and complete animal protein sources, it made sense because seasonal summer stress made us neurochemically inclined to prefer energy-dense, sugary foods over complete, more