Given that in the Northern hemisphere June is the month of the summer solstice, (first day of summer and longest day of the year), it seemed ideal timing to write a piece on the very real connection between the 24-hour period which follows the earth’s rotation around the sun known as the circadian clock and our bodies own natural rhythm. We all know that the earth revolves around the sun and that it takes close to 24-hours to get this done. But, did you know that our bodies also have a natural metabolic rhythm that mimics the rhythm of the circadian clock? The circadian clock interfaces with metabolism in numerous ways that are essential for maintaining metabolic homeostasis.1 And when our lifestyles are out of sync with the circadian rhythm this takes us away from optimal health and our ability to lose fat. It’s all true and simply stated, not eating and living in sync with the rhythm 24-hour clock can lead to non-caloric weight gain and increased stress-levels.2
Body Metabolism, Circadian Rhythm & Meal Timing
When we awaken in the morning our body metabolism starts to rise and begin its day as does the sun. Our temperature increases naturally to prepare us for this metabolic resurgence. Within an hour of waking is the optimal time to break our nighttime fast. Our body needs fuel (real food consisting of healthy protein, veggies, and fat), to lay a foundation of health and energy for the remainder of the day. I know many insist they are never hungry for breakfast and therefore skip this meal. Because eating a morning meal is so important for the maintenance and regulation of our body’s metabolism, I’m going to mention 2 ways to allow your natural morning appetite to awaken and come alive.
First, if you consume coffee first thing in the morning prior to eating, hold off. Caffeine is an appetite suppressant and very easily can block your natural, healthy appetite.3 (No, this is not good as appetite is not bad! On the contrary, appetite is essential or we would have to force eat in order remain alive.) Second, become really mindful of your eating style later in the day/evening/nighttime. Frequently people who eat the majority of their calories during the last 1/3 of their day and go to bed with a full stomach experience lack of an appetite in the morning. Because digestion slows down during the night, you may not have fully digested your nighttime meal, and consequently feel sluggish, tired, and full in the morning. And by the way, eating heavily in the last 1/3 of your day and skipping breakfast leads to increases in body fat. If you don’t believe me, go ask your local big bodied sumo wrestler about his secret to success with regard to gaining fat. He will tell you that he eats heavily at night and goes to sleep shortly thereafter.4
Our metabolism continues to rise and reaches its peak, with some variation from person to person, between 11am-2pm. In other words, our metabolism is at its highest when the sun is at its highest around high noon. Lunch is the perfect time for our largest meal of the day. Makes sense doesn’t it? We’ll have the best opportunity to digest the food and assimilate the nutrients from the food because our metabolism is pumping away. Lunch, and actually all your meals, ideally should consist of the same food groups – healthy protein, veggies, and fat. It’s the portions that need to vary according to the time of day.
Between 2-5pm, our metabolism decreases. If you feel tired or sleepy during the afternoons, there’s a good reason. In many European countries this is their siesta time when they stop working and take it easy for an hour or 2. In the USA and other cultures where siestas not only don’t exist in the workplace but actually are frowned upon, I suggest simply closing your eyes for 15 minutes and resting. I know many of you are thinking that there’s no way you could possibly sneak 15 minutes of quiet time for yourself at work. How about a 10 or 5 minute rest? Relaxation and rest especially during the work week frequently means developing the active state of mindfulness and interest in our health and well being at least equal to our desires to perform well on the job. And the two, resting and improving job performance, do not have to be at odds. On the contrary, chances are our work performance will increase when we feel well. Moreover, get in 2 rest periods a day, and we’ll be doing our bodies a huge favor. The body will thank us with a nourishing refreshed and recharged feeling.
Metabolism and appetite come back up between 5-9pm, but not to the degree they were during the high noon period. Yes, we have a surge out of “siesta” but the body, with its internal rhythm that mimics the cycle of nature, is also getting ready and preparing for the end of the day. This is dinner time. Eat your meal with gusto and pleasure but consider not having this be your largest meal of the day. Leave that to lunch. With all our meals, slow down the pace of eating, relax, enjoy, and nourish. Eating, whenever possible, should stop by 9pm. In fact, many people I know prefer to eat not only within these time frames, but limit their food consumption to when the sun is still shining. This means in the winter dinner is eaten far closer to 5pm than 9. It’s best to allow between 2-4 hours after consuming your last bite before finally going to bed.
With a simple calculation, if we finish eating our last bite of anything by 9pm and leave the minimum 2 hours for digestion and assimilation, it’s now 11pm. The sun has long ago set and it’s time for artificial lights out. During sleep, our blood pressure, heart rate, and body temperature decrease. This is a time for our bodies to clean, repair, and produce growth hormone. Give yourself approximately 8 hours for deep rest and sleep. Many people short change themselves of this especially important healing period for the body and mind. Fully nourished, recharged and in sync with the bio-circadian-nutrition rhythm, we are ready to take on the stressors and pleasures of the new day. We also set up the greatest long-term optimal health and fat loss possibilities.
What we eat and how we move/exercise are the 2 major components the masses focus upon to lose weight. While both are important, clearly there are other factors involved which should formulate the overall picture of sound health, comfortable body size and a happy life. This article proposes that when we eat, in accordance with the circadian clock, is as important as what we eat. In future articles, we’ll go beyond the what and when factors to the who-we-are and how-we-eat elements. Stay tuned for more great info!
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1. K. Eckel-Mahon & P. Sassone-Corsi, “Metabolism and the Circadian Clock Converge,” APS, Physiol Rev. 2013 Jan, 93 (1) 107-135
2. M. David, The Slow Down Diet: Eating for Pleasure, Energy & Weight Loss (Rochester, Vermont: Healing Arts Press, 2005): 82-101.
3. B. Benjamin, Ph.D. & L. Orth-Zitoli, “Boost Your Metabolism by Knowing When to Eat,” (blog: April, 2012, Vol. 12, Issue 04), Women in Bodywork, Massage Today
4. K. Haisch, BS, ”How to Eat Like a Sumo Wrestler,” Eating Free, MV Nutrition LLC, 2015