- Intermittent fasting may boost your mental and physical energy, prime your immune system to fight illness, and strengthen circadian rhythms.
- In winter, levels of the hunger-stimulating hormone ghrelin go up, while levels of leptin—the hormone that produces feelings of fullness—go down.
- Spreading movement throughout the day, in short periods, helps keep energy levels consistent.
Why is now the time to consider a shift to intermittent fasting? It may boost your mental and physical energy, keep your immune system primed to fight illness, and strengthen circadian rhythms that have a major influence over your sleep and your mood. And it’s an excellent aid in maintaining a healthy weight.
Influence of Stress and Season on Eating
If you’re anything like me (and a lot of other people), stress can make you want to eat more, eat differently, and eat more often. Combine the stressful, routine-busting reality of COVID-19 and typical seasonal changes to appetite (winter carb cravings, anyone?) and that’s a recipe for eating throughout the day and into the night.
Studies show calorie intake goes up during the winter months. We also experience seasonal changes to our hunger hormones. Levels of the hunger-stimulating hormone ghrelin go up in winter, while levels of leptin—the hormone that produces feelings of fullness—go down.
Lots of us crave more carbohydrates during the winter. Our increased drive for carbs during this season may have to do with carbohydrates' connection to serotonin. Carbohydrates increase serotonin production, which drops during the winter. Our winter cravings may be our bodies attempting to elevate depressed winter moods.
Grazing throughout the day and snacking late at night is tough to resist in winter—and especially during a winter when we’re feeling exceptionally stressed and isolated from people and from the freedom to safely pursue the activities and routines that bring us pleasure, stimulation, and joy.
People are sometimes wary about intermittent fasting. They think it means starving themselves, or that fasting itself will just be too difficult. Intermittent fasting isn’t about depriving yourself of food. You can eat the same number of calories you otherwise would in a day. (Though most people wind up consuming fewer calories, without trying.) The difference is you’ll consume those calories within a shorter window of time, giving your body a break from constant digesting and giving it a chance to actually use the calories you’ve consumed for energy, rather than storing them as fat, which is what happens when we eat throughout the day and right up to bedtime—even if you’re eating a fantastically healthful diet.
The when of eating, informed by both chronotype and body type, is the single most important daily dietary choice you can make—it is a transformational shift for both energy and sleep.
As for the difficulty in fasting itself? Research has shown that fasting actually increases levels of the hormone leptin, which signals fullness. Within a day or two of adopting an intermittent fasting routine, your body adjusts, and appetite decreases.
Chronotype and body type are the keys to understanding our individual best times for eating throughout the day, and the ideal length of our eating and fasting windows.
Beyond its ability to shift the body into fat-burning mode, daily intermittent fasting—feeding over a duration of 8 to 12 hours and fasting for 12 to 16 hours (six to eight of those being sleeping hours) has a broad range of benefits:
- Increasing metabolism and speeding up energy expenditure (the calories we burn for all activity other than exercise)
- Lowering blood sugar
- Reinforcing circadian rhythms
- Activating the body’s cell repair and cell rejuvenation mechanisms
- Strengthening our immune systems
- Helping us make better food choices
- Sharpening cognitive focus
Every chronotype has different daily rhythms for hunger and appetite hormones and different optimal times for eating throughout the day.
And each body type has a different ideal eating window and fasting period.
- Endomorphs (thicker types who tend to gain weight at the midsection, with typically slow metabolisms) gain the most energy from an eight-hour eating interval and a 16-hour fasting interval.
- Mesomorphs (with typically medium metabolisms) do best with a 14-hour eating interval and a 10-hour fasting interval.
- Ectomorphs (long, lean types with typically fast metabolisms) derive their optimal energy from a 12-hour eating interval and a 12-hour fasting interval.
A daily routine of eating and fasting is way easier than you may think to adopt, and it provides an almost immediate energy boost, as well as delivering foundational benefits for physical and mental health, and restful sleep.
Short Bursts of Movement Throughout the Day
Use short bursts of movement to keep your energy flowing consistently throughout the day.
Our daily energy levels fluctuate throughout the day, even in the best of times, when we’re well-positioned to make choices that enhance our energy and health. For a lot of people, these are very much not the best of times. Energy dips can drag you down mentally and physically—even more so when you’re feeling exhausted, stressed, and isolated.
One of the most powerful benefits of spreading movement throughout your day, in short periods, is that it keeps energy levels consistent. Five times a day, you’ll prime your body battery, keeping energy flowing steadily and avoiding the energy dips that can be physically, mentally, and emotionally draining, especially when you’re under pressure or experiencing stress.
This winter, give yourself permission to let go of the idea that you must do 30- or 60-minute workouts. Set up a sustainable routine of five minutes of intentional movement, five times throughout the day.
Finally, along with self-care, self-compassion is deeply important right now. These past couple of years have been tough on us all. Be gentle with yourself as you use these strategies to bring energy, calm, rest, and a sense of peace into your life.
Michael J. Breus, Ph.D., DABSM
The Sleep Doctor