Every year hundreds of new books are published about how to lose weight and get healthy. New gyms open. More and more research is done on the ideal diet and exercise program. Well-meaning medical doctors write life-changing, meme-filled, snarky blogs. Despite all these efforts, America’s waistline continues to increase. Why are these diets and exercise programs failing? Could it be that we are missing a huge piece of the health and weight loss equation? Yeah, we are missing something really big and I’m not just talking about fasting. America is chronically underslept. This lack of sleep is making us overweight, diabetic, and also quite sleepy. I will explain…
Below are obesity rates in the U.S. by year as compared to our average sleep amount. As we get less sleep, our weight increases. Why does this happen? There are lots of reasons, but first, a couple disclaimers. First, I don’t believe that sleep deprivation is the only cause of our obesity epidemic. Second, the graph below only shows a correlation which doesn’t prove that insufficient sleep causes obesity. In the next few paragraphs, I will make the case that sleep plays a much bigger role in our health and fitness than most of us think, in the hopes of motivating you to stay in bed longer. I know “stay in bed longer to lose weight” sounds like clickbait, but just keep reading. That also sounds like clickbait.
While the above graph shows a strong correlation between sleep and obesity, it’s still just a correlation, and better studies are needed to show if poor sleep is actually causing obesity. The fictitious lower graph shows that as pirate prevalence goes down, global population goes up. This is also a correlation, but probably mostly coincidental. So, we shouldn’t be fooled by statements solely based on a correlation, that’s bad science.
Fortunately, in recent years there have been many scientific studies showing a causal relationship between lack of sleep and obesity even after adjusting for factors like exercise, age, sex, and proximity to a Cinnabon. Here is the link. Why does insufficient sleep causes weight gain? Great question. One important and often overlooked cause is hormonal. When we don’t get the proper amount of quality sleep, a stress hormone called cortisol goes up. High cortisol causes us to lose muscle and gain fat, regardless of what we eat! Cushing’s syndrome is a disease characterized by too much cortisol and the effects (shown on the right) are devastating and very similar to persistent lack of sleep. High cortisol from lack of sleep or Cushing’s syndrome makes getting healthy as f**k impossible.
Incidentally, Addison’s disease is when cortisol levels are too low (opposite of Cushing’s syndrome). JFK had this disease. The symptoms are tan skin, thin appearance, extra confidence, and frequent, aggressive episodes of coitus.*
Sleep loss just doesn’t cause obesity, but it can also lead to type 2 diabetes. Rates of type 2 diabetes are much higher in under-slept adults, but like the pirates and global population, this was just a correlation, until one study took a group of healthy fit young people and limited half of them to just four hours of sleep per night. The researchers fed both groups the same healthful food. After just one week, the under-slept group’s blood sugar levels were so high, they qualified as “pre-diabetic”! WTF? I’ve been taking care of diabetics and pre-diabetics for years. Why am I just learning this? This has been repeated in different studies with even less severe sleep disruptions. Type 2 diabetes will take an average of 10 years off of your life, but even just having slightly high blood sugar triggers high insulin, increased body fat, and a host of other bad stuff. Here’s my article about insulin and blood sugar.
Lack of sleep makes us hungry as f**k. Pro-satiety hormones (leptin) and pro-hunger hormones (ghrelin and endocannabinoids) all go in the wrong direction after just two nights of poor sleep (6 hours or less). This is a double or even triple whammy for weight gain, because these hormones cause us to be persistently hungry but also not fully satisfied by eating. In one well controlled experiment done at a sleep study hotel, patients ate an average of 340 calories more per day when they were restricted to six hours sleep as compared to when they were allowed 8 hours sleep. Additionally, those sleep deprived subjects tended to choose more junk food (cookies, pretzels, chips, Chili Lime Cheetos, etc) and they reported excessive cravings for high carb foods. Basically, not sleeping enough gives us the munchies.
Poor sleep crushes dieting efforts and causes muscle loss. One study took a group of dieters and let half of the subjects sleep normally and sleep restricted the other half to just 5.5 hours per night. While both groups lost weight, the low sleep group lost mostly muscle while the group that got good sleep, lost mostly fat. Losing muscle while retaining fat lowers our metabolism and makes us less sexified, technically speaking. This is the opposite of bueno, I might even dare to say it’s no bueno. If you haven’t noticed, the theme of this article is that good sleep helps us lose weight.
How did one group or researchers turn a group of virile, strapping men in their 20’s (think shirtless Abercrombie and Fitch models spraying each other with water from a hose) into a bunch of middle aged dad-bods with jean shorts on riding lawnmowers? They limited their sleep to only 5.5 hours. This sleep restriction aged these young men by 15 years in terms of their testosterone levels. Testosterone is important for weight because it promotes muscle building while simultaneously decreasing body fat and low testosterone in men is linked to truncal obesity. Sufficient, restorative sleep boosts testosterone and also growth hormone which is responsible for injury repair, muscle growth, resurfacing the lining of blood vessels, and essential for healthy cardiac function and blood pressure. Growth hormone is also the number one reason NFL players visit doctors in Mexico, so you know it must be good.
While there is some evidence that exercise improves sleep, more research is needed in this area. What has been repeatedly shown is that great sleep boosts your exercise performance and poor sleep greatly decreases your ability and likelihood of exercising. Shawn Stevenson’s book, Sleep Smarter recommends morning exercise as a key for better sleep at night. Don’t worry, I’ll go into my recommendations for getting great sleep in my next post.
Many of us are trying so hard to get thin and healthy that we are waking up at 4 AM to go to the gym, spending tons of money on powders, pills, food scales, and Lululemon apparel and not getting the results we could get from simply staying in bed and getting a great night’s sleep. This should come as great news because sleep is free and it feels amazing.
In conclusion, poor sleep makes us gain weight by screwing up our hormones, spiking blood sugar, lowering our metabolism, shrinking our muscles, holding onto body fat, increasing our cravings, and sabotaging our workouts. Clearly, getting sufficient quality sleep should be a priority of anyone who is trying to get healthy as f**k or maintain their healthy as f**k status. It’s ridiculous that this is not more emphasized by the health community. It’s clear from my research that not getting enough quality sleep is the perfect activity, if your goal is to become obese, diabetic, and sleepy. I will put out my best sleep improvement tips in the next few days. Thanks for reading.
*Addison’s disease is a rare autoimmune disease that is characterized by low cortisol. Symptoms include fatigue, weight loss, low blood sugar, hyperpigmentation of the skin, and depression. JFK had this disease. I’m not kidding. I was kidding about the coitus part.
One of the primary resources for this article was the amazing book, Why We Sleep by Dr. Mathew Walker. I highly recommend it.