As a Nutritionist when I work with clients we are obviously talking a lot about food, but what surprises a lot of people is that we are also talking a lot about their lifestyle. That’s because things like environment, toxic load, stress, and sleep all have an impact on your hormones, health, and weight. Does it surprise you to learn that there is a link between sleep and weight gain?
How much you sleep and how much you weigh are connected, which is why I always say “If you want to get serious about losing weight, you have to get serious about sleeping“. I know the lifestyle changes can be some of the hardest to put into place, but they are also the changes that can really move the needle on your progress. Here’s the deal on why sleeping more can help you weigh less.
The Link Between Sleep and Weight Gain
It may not be obvious that there is a link between your sleep habits and your weight, but more and more research is showing just how important sleep is for your mood, mental performance, overall health and wellness. Especially when it comes to maintaining a healthy weight.
Many studies show that people who have a short sleep duration simply weigh more. And, in fact, as the levels of chronic (long-term) sleep deprivation have increased over the past 50 years, so have the growing epidemics of being overweight or obese.
And many studies now agree that lack of sleep is an “independent” risk factor (i.e. a direct risk) for weight gain and obesity.
Especially for women.
One large analysis of 45 studies which included over 600,000 people says, “studies from around the world show a consistent increased risk of obesity amongst short sleepers in children and adults.” The increased risks were 89% for children and 55% for adults.
The overall data in that study suggests that a reduction in one hour of sleep per day would be associated with about 1.4 kg in additional weight.
Right now, 40% of American adults say that they get less than 7 hours of sleep per night, and 7 hours is the minimum recommended nightly sleep, with 9 being the maximum. You need 7-9 hours of sleep per night, and so many clients I see are only getting 5-7. Sleep is so important to your body for meany reasons, and if you want to maintain a healthy body weight it is a key strategy to start implementing right now.
How Sleeping Less Leads To Weight Gain
Overall, there are two mechanisms that we think that lack of sleep contributes to weight gain and obesity; increasing energy reserves (calories and fat storage) and decreasing energy expenditure. Your big goal may be to fit into your favourite jeans or look great for an upcoming event, but your body’s main goal is always survival. From an ancestral perspective, lack of sleep meant more time to be on the move, looking for food, caregiving and being alert. Your body needs energy to do this, and responds with the 1-2 punch of increasing energy reserves and decreasing energy expenditure. It doesn’t know that you aren’t sleeping because you binge watched a new show on Netflix, were worrying about a deadline at work, or decided that folding the laundry can’t wait until tomorrow. Like the Backyardigans, your body is ready for anything, and survival is the name of the game.
So how does it do that?
Your body increases calorie intake in two ways:
- It changes your hormones.
- It allows more time available to eat.
Your body decreases your ability to burn off calories in two ways:
- It can slow your metabolism; and
- It can cause fatigue and, therefore, reduced physical activity.
Here’s the deal on all four of these factors.
Lack Of Sleep Changes Your Hunger Hormones
This is a biggie. Many people who sleep less tend to eat more calories throughout the day. And not only due to increased time available for snacking, but also because of how lack of sleep can mess with the hormones that control both hunger and appetite.
How does this happen?
This is a “double-whammy” because some studies show that lack of sleep not only increases the stomach’s hunger hormone “ghrelin” (making you hungrier), but it also decreases the fat tissue’s fullness hormone “leptin” (making you feel less full).
These changes can clearly lead to more eating, and eventually weight gain or even obesity.
It’s possible that this is a natural mechanism that our body uses to make sure we get enough food for longer waking times. But in our modern lifestyle, this doesn’t always serve us well as it tends to make us “overshoot” our energy needs and take in more than we actually need. We also know that all our hormones work in synergy, and that when one is out of balance others are often out of balance. Lack of sleep can increase production of the stress hormone “cortisol”, which can also lead to weight gain, particularly in the abdomen (“belly fat”).
This hormone connection is the #1 reason I have my weight loss clients make prioritizing sleep one of their very first goals.
Less Sleep Means More Time To Eat
Some researchers suggest that the longer the time you’re awake, the more opportunity you have to eat, or more specifically, to snack. In fact, some studies have shown that these tend to be nighttime snacks.
And guess what many sleep-deprived people tend to snack on at night?
You guessed it…high-fat, sometimes high-carb, and less protein and fibre snacks. Which, of course, can lead to weight gain.
And, at least one study shows that eating at night increases the time it takes (healthy people) to fall asleep. Especially for women. So there is a bit of a “vicious cycle” in play here. Being tired also reduces your resilience, making it much easier to say yes to those donuts break room or to finishing off your kid’s leftover macaroni.
Sleep and Your Metabolism
Research is just emerging on this topic, but it seems to show that sleep deprivation can lower your “energy expenditure” and body temperature. This means that your body may naturally burn less fuel at rest during the days when you’re sleep deprived. This is possibly an evolutionary mechanism; the body has a desire to stay in balance including energy balance. Just like when you exercise more you get hungrier, our bodies may be preparing for more energy expenditure by storing more fat for fuel.
Lack of Sleep Reduces Exercise
You know how tired you feel after not getting enough sleep?
By increasing fatigue, sleep deprivation can reduce the motivation to exercise. This doesn’t just mean going to the gym, but ev-er-y-thing you do. The energy you burn just doing your daily routine is called NEAT (non-exercise activity thermogenesis) and it can vary wildly from day to day. Your body naturally compensates your activity in order to keep your energy in balance. Again, that’s that whole survival mechanism at play. If you’re awake more hours, your body wants to make sure you have energy reserves to last and all the little things you do every day, from get up and stretch, to taking a walk for fun, to fidgeting will be reduced to conserve energy. And when you’re burning less fuel at rest (slower metabolism), and less likely to exercise, you’re at risk of gaining weight.
Putting It Into Place
So if you’re serious about losing weight, you need to be serious about sleeping. I know it’s much easier said than done, but making sleep a priority in your life is truly worth the effort. Need some help getting more shut-eye? Read Part 2: Tips for Getting More Sleep.