Why Is Sleep So Important For Weight Loss And Management?

Are you overweight or obese?

Terrifyingly, 2 out of 3 adult Australians answer ‘Yes’ this to question – and a quarter of Australian children.

Weight loss and management are two hot topics in Australia at the moment (and no wonder!). With the multitude of both physical and mental health risks associated with obesity, people everywhere are trying to find ways to take better care of themselves and their families.

Diet and exercise are the two main areas addressed by those trying to lose weight and those trying to help others to do so – but there are a multitude of other factors which contribute to living a healthy, balanced lifestyle… sleep being one of the most important (and overlooked!).

Did You Know?

• More than 35% of Australians are sleep deprived.
• Poor quality or short sleep duration over a long period of time increases the likelihood of obesity by 55% in adults… and 89% in children.
• One study found that when adults sleep only five hours per night they gain an average of 0.82 kgs over five days!

• Sleep is when you actually lose weight (not when you’re shredding it at the gym!).
• Sleep deprivation leads to more cravings, increased appetite, a decrease in satiety, and less motivation to exercise.

Sleep Deprivation Slows Your Metabolism

Yup, that’s right! The less you sleep the fewer calories you burn. But why?

Think about it – when you’re tired you feel sluggish, your brain works slower, you don’t go about your day as normal… so why would your metabolism be any different? Coined ‘metabolic grogginess’ by the University of Chicago, a slowing of your metabolism occurs when you are in sleep debt.

Metabolic grogginess is a result of a drop in your body’s insulin sensitivity. Insulin is responsible for removing fatty acids from your bloodstream and preventing fat storage. When it’s levels become disrupted this process doesn’t happen as efficiently, which results in the storing of more fat. Or in other words, the less sensitive your body is to insulin the more fats that circulate, which means your body produces more insulin to compensate and your body ends up storing more fatty tissues throughout your body.

Fact: When you’re sleep deprived your insulin sensitivity can drop by as much as 30%. Skip your shut eye for too long and this can quickly translate to weight gain!

Lack Of Sleep Results In Loss Of Muscle

Sleep debt is the enemy of muscle.

Sleep is an important part of the day for your body as it’s when it is given time to rest and repair. Protein synthesis (the process of repairing and building muscle) occurs predominantly while you’re sleeping, therefore by decreasing the amount you sleep you also reduce your lean muscle mass.

During sleep is also when your body releases most of its growth hormone – your naturally occuring fat burning, anti-ageing, body repairing super-remedy. When you suffer from a bad night’s sleep less of this hormone is released… and more cortisol hits your system to compensate. Cortisol not only further restricts your body’s production of growth hormone (double whammy!) but high levels of cortisol over a prolonged period of time also contributes to weight gain, as your body will start turning to lean muscle for food. Muscle burns more calories at rest than fat does, so the less muscle you have the slower your metabolic rate… and the easier it becomes to gain weight.

Want more proof? One study monitored the effects of a calorie restricted diet on 10 overweight adults. Half of those adults had 8.5 hours sleep, the others only 5.5. The adults who slept properly saw fat loss… while those who experienced less sleep loss more weight from muscle than fat! Another study from the American Journal of Clinical Nutrition reported that people who enjoy adequate sleep have a BMR (basal metabolic rate) 5% higher than those who don’t sleep enough… and can burn up to 20% more calories a day than their sleep deprived counterparts!

(Want to learn more? For info on the effects of high cortisol in the body, check out point seven in our blog “10 Things You Didn’t Know About Weight Loss).

The Less Sleep You Get, The Hungrier You’ll Be

The two main hormones controlling hunger in the body are leptin and ghrelin. Leptin is produced in your fat cells and tells you when your stomach is empty. The less leptin you produce, the hungrier you feel. Ghrelin stimulates hunger, slows your metabolism and increases the amount of fat your body stores.

Clearly, when you’re trying to lose weight these are two hormones you need to keep in control of! Unfortunately, when you’re sleep deprived it becomes a near impossible feat. In fact, when you’re in sleep debt your leptin levels are naturally reduced and ghrelin increased… all while you’re cortisol levels are stimulated and growth hormone depleted!

Together, these variances in hormones prevent your brain from being able to identify when you’re satisfied after a meal, resulting in overeating. Skip sleep enough, and you’ve got yourself a serious problem!

Being Tired Is Similar To Being Drunk…

Just one night of bad or short sleep reduces activity in your brain’s frontal lobe, which is where you make all of your complex decision making. This means you lose the ability to make rational or well thought out decisions – such as choosing or preparing a meal.

To make things even trickier, when you’re tired activity in your amygdala – the reward part of your brain – increases. Say hello to sugar and fat cravings! And, conveniently, your insular cortex (yet another part of your brain) which is responsible for fighting these cravings, is weakened due to lack of sleep.

Sound similar to a Friday night out?

And as if all this wasn’t enough already, the more tired you are, the larger portions of food you choose. Multiple studies have proved this – one in particular showed that adult men whose sleep has been cut in half eat an average of 559 more calories the next day, compared to when they are well rested.

Make Sure You Get Enough Sleep – Just Don’t Go Overboard

Adults should be looking at anywhere between 7-9 hours sleep a night, teenagers 8-10 and school children between 9-11. Make sure your sleep is quality and restful, and try to avoid excessive napping during the day.

If you inclined to go the other way and sleep more than the recommended average, you could also be doing yourself a disservice. Spending too much time with your eyes shut means you’re missing important meals and not performing enough physical activity to spur your metabolism and other bodily functions. The trick to living healthy, losing weight and staying fit is BALANCE, and sleep is no exceptional to the rule!