You’ve likely heard it before and probably more than once, that a good night’s sleep is worth its weight in gold. Well, surprisingly, it couldn’t be more true than when we’re looking at the relationship between sleep and weightloss.
Many of us began the New Year, like every year(!), with iron-fast resolutions of diet change and regular exercise programs – determined to hit summer looking like the front-cover of a swimsuit mag. Yet as summer fast approaches, many of us have tossed the towel in because despite a horrendous amount of effort, the pounds stubbornly remain.
What gives?! You’ve done more than ever to shift the scales – painfully early morning spin classes, meal planning, lunch packing, dietary restrictions, saunas, evening yoga classes…and the list goes on. What could possibly be missing??? What more could you have done???
What if I were to tell you that in order to lose weight, it’s not about doing more, but rather, doing less?! That you need to pull the plug earlier at night?! That you need more sleep! There is mounting scientific evidence that our sleep, and more accurately, our lack of good quality sleep, may be a major cause of weight gain and obesity.1 And the reason for this, lies within the intricate web of our circadian and hormonal rhythms.
How circadian rhythm and hormones impact weight loss
Circadian rhythms, or daily rhythms as they’re often called, are highly complex biochemical, physiological and behavioural processes that run our bodies. Through a tightly regulated ‘power-and-control’ dynamic they share with our hormones, these rhythms govern pretty much everything we do: they run our sleep / wake cycle, our eating patterns and even how much energy we expend in a day. In short, everything to do with our weight is governed by our circadian body clock which, when we we break it down, is controlled by our hormones!
4 ‘Sleep’ hormones that affect weight loss
The hormones that control our daily rhythm function in perfect balance ~ cortisol juxtaposed with melatonin, leptin balanced with ghrelin. There are dozens of hormones involved in the metabolic dance of sleep and weight balance, but these 4 are huge players. The proper secretion of any one of these has significant downstream hormonal effects. Balance these, and you create a domino effect of hormonal health that puts your body on the map to successful weight loss!
Melatonin
Melatonin stands opposite cortisol in the drumbeat of our sleep / wake cycle. It is secreted by the pineal gland in complete darkness which, historically, would have been by about 10 pm virtually anywhere on the globe. But in today’s night-lit world, our balance of melatonin is easily altered, which research indicates may have significant long-term health consequences including weight gain9.
Melatonin does much more than just regulate our sleep / wake cycle – it causes a cascade of hormone secretion that impacts our entire metabolic rate, our ability to burn fat, and our hunger drives – all of which wreak havoc on the scales1,4-9. And if this weren’t enough, melatonin is a powerful antioxidant that counters the negative effects of inflammation9, a primary cause of numerous disease states including obesity². The evidence is stacking up – GET MORE SLEEP!
Cortisol
Secreted by the adrenal gland (tiny little glands that sit above the kidneys), cortisol is most famously known as the body’s number 1 stress hormone. In this capacity, cortisol functions to save our lives from the perilous attack of a saber tooth tiger (13,000 years ago!) or the ruthless and all-too-frequent attack of negative self-talk that many of us have. But regardless of the stress we face – physical or mental / emotional – cortisol is secreted. And unfortunately, many of us have far more stress than we are evolved to handle (our adrenal glands are tiny for a reason – they are not designed to pump out massive amounts of stress hormone every day!).
Chronic stress results in cortisol imbalance, which means our melatonin goes out of balance too. (Remember, these two sit on opposite ends of the teeter totter – when one is high, the other is low). Melatonin secretion peaks between the hours of 10pm and 2am. When melatonin wanes, cortisol begins. This is the balance of our sleep / wake cycle.
The adrenals have evolved to be the body’s natural alarm clock. They are designed to secrete small amounts of cortisol starting around 2 or 3 in the morning. However, if there has been too much stress during the day, this early morning secretion goes hay-wire and we find ourselves wide awake at this time. This wreaks havoc on our circadian rhythm. Our energy cycles go off, our hunger hormones rage and our weight loss program of diet and exercise goes down the tube!1,7
Leptin and Ghrelin
Leptin and ghrelin are our ‘hunger hormones’. Leptin is often thought of as the ‘satiety’ hormone, as it decreases appetite. Secreted by adipocytes (fat cells), it is responsible for our sense of feeling ‘full’. It is normally found in higher concentrations in the evening, which serves to curb our late-night appetite.
Ghrelin, on the other hand, is secreted by our stomach cells to increase appetite. In a study published in the Annals of Internal Medicine, it was noted that when study subjects were deprived of sleep for two days, their blood leptin levels decreased by 18%, while their ghrelin increased by 28%. Subjects reported an increase in hunger (24%) with carbohydrate rich foods being the most highly craved items (32%)³.
Sleep more and lose weight!
Now that you know it may be your chemistry and not your resolve that is failing you, the best thing you can do to support your weight loss effort is to get a good night’s sleep. You have already done enough. So go ahead, tuck yourself in and grab some good quality zzz’s!
References:
1. M,E., R,K. & JB. 2010. Circadian rhythms and metabolic syndrome: from experimental genetics to human disease. Circulation Research, 106: 447-462.
2. H,G., E,E. 2008. Nutrient sensing and inflammation in metabolic diseases. Nature Reviews Immunology, 8: 923–934.
3. S,K., T,E., P,P. & E,V. 2004. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels and increased hunger and appetite. Annals of Internal Medicine, 141:846–50.
4. K,K., S,K., P,P. &, E,V. 2007. The metabolic consequences of sleep deprivation. Sleep Medicine Review,11: 163–178.
5. Valcivi, R., Zini, M., Maestroni, GJ., Conti, A. & I. Portiolli. 1993. Melatonin stimulates growth hormone secretion through pathways other than the growth hormone-releasing hormone. Journal of Clinical Endocrinology, 39(2): 193-9.
6. Vijayakumar, A., Yakar, S. & D. LeRoith. 2011. The intricate role of growth hormone in metabolism. Frontiers in Endocrinology, 2:32.
7. Hastings, M., O’Neill, J. & E. Maywood. 2007. Circadian clocks: regulators of endocrine and metabolic rhythms. Journal of Endocrinology, 195: 187-98.
8. Anonymous. 2011. Daytime sleepiness is associated with an increased craving for carbs among teens. American Academy of Sleep Medicine. Accessed May 2017 from Science Daily.
9. Esposeto, E. & S. Cuzzocrea. 2010. The antiinflammatory effects of melatonin in the central nervous system. Current Neuropharmacology, 8(3): 228–242.
