How Poor Sleep Can Affect Client's Fat Loss Results

sleep Jul 15, 2019

Why is Sleep Important?


The National Sleep Foundation recommends that adults sleep for seven to nine hours a night. With life, work and family pressures, many people find it challenging, even impossible to consistently reach these durations of sleep. It’s well known that ‘sleep is good for us’, but sometimes we all need a gentle reminder of the consequences of sleep restriction or deprivation, and this can provide the perfect motivation for us to prioritize good sleeping habits. 


Sleep loss is a potent stress that creates a catabolic environment for the body. The change in hormones caused by sleep loss significantly increases the risk of metabolic dysfunction and can result in a loss of muscle mass, strength, and physical function. In a recent study, Lamon et al. (2021) demonstrated that a single night of sleep deprivation induced anabolic resistance, reducing muscle protein synthesis rates by 18%. Sleep loss also increased the catabolic stress hormone cortisol by 21% and decreased the anabolic hormone testosterone by 24%. Similar findings were reported in a study that examined five nights of sleep restriction (Saner et al., 2020).


Related to anabolic resistance is our body composition and the ability to lose fat while preserving muscle mass. Sleep loss is strongly associated with negative changes in our fat to muscle ratio. In one study, sleeping less than the 7-8 hours a night was linked to having greater body fat and negatively influenced how easily participants lost weight when in energy deficit. Another study found that sleeping 5.5 hours each night over a two-week period while dieting resulted in less fat loss when compared to sleeping 8.5 hours each night. And, worse, it also resulted a greater loss of muscle mass. Similar to the findings of reduced testosterone above, another investigation showed that daytime testosterone levels were decreased by 10% to 15% in a group of young healthy men who underwent 1 week of sleep restriction to 5 hours per night, a condition experienced by at least 15% of the adult population. By comparison, normal aging is associated with a decrease of testosterone levels by 1% to 2% per year. Symptoms and signs of androgen deficiency include low energy, reduced libido, poor concentration, and increased sleepiness, all of which may be produced by sleep deprivation in healthy individuals.


How Sleep Can Slow Down Weight Loss


In addition to the hormonal changes that occur during sleep loss, there are several other reasons why shorter sleep may be associated with higher body weight and affect the rate of weight reduction and the composition of weight lost. These include changes in metabolism, appetite, and food selection.

Sleep influences two important appetite hormones in our body – leptin and ghrelin. Leptin is a hormone that decreases appetite, so when leptin levels are high, we usually feel fuller. Ghrelin, on the other hand, is a hormone that can stimulate appetite, and is often referred to as the “hunger hormone” because it’s believed to be responsible for the feeling of hunger.

Research has found that sleep restriction increases levels of ghrelin and decreases leptin.  This combination increases appetite, making energy-restriction more difficult to adhere to, and increases the likelihood of overeating. 

Along with changes in appetite hormones, reduced sleep has also been shown to impact on food selection and the way the brain perceives food. Research has shown that the areas of the brain responsible for reward are more active in response to food after sleep loss (six nights of only four hours’ sleep) when compared to people who had good sleep (six nights of nine hours’ sleep). 

This most likely explains why sleep-deprived people snack more often and tend to choose fast-digesting carbohydrate rich foods and sweet tasting snacks, compared to those who get enough sleep. Sleep deprivation also increases the total amount of food and energy density via unhealthy food choices during the day. 

Sleep duration also influences metabolism, particularly glucose metabolism. When carbohydrate and protein is consumed, our bodies release insulin, which is a hormone that helps to process the glucose in our blood. However, sleep loss can impair our bodies’ response to insulin, reducing its ability to uptake glucose. A single night of sleep restriction (only four hours’ sleep) is enough to impair the insulin response to glucose intake, rendering the subjects “diabetic” for the duration of the sleep restriction

Given the clear implication for healthy body composition, here are some guidelines for improving the quality of sleep:

Duration: determine what the ideal amount of sleep is for you: the range is individual but will be between 7 to 9 hours per night. Be disciplined with your sleep duration. Know when you need to wake up and work back from then to know your ideal bedtime.


Consistency: Once you have identified your sleep duration, consistency is as important – maintaining a regular sleep-wake cycle. The circadian rhythm has been evolutionary engrained into our biology. Respecting consistent sleep-wake times sets our daily rhythms and cements an ideal sleep architecture. You cannot bank sleep by skimping on sleep during the week and binging on the weekend. 


Night and morning routines: Use dim light or candles at night to promote melatonin release. Similarly, wear blue blocking glasses and if you are using screens, make sure they are switched to ‘night mode’. Ideally, avoid screens within an hour of bed. Enjoy your last meal as far from bedtime as possible – try three hours before retiring at night, and make sure it is not too large a meal. Warm baths and showers aid in the cooling of the body when we are falling asleep, allowing us to be ushered into deep sleep faster. If you find you’re your mind is busy with thoughts, journaling is an excellent way to drain the brain of thoughts that might delay us from sleeping.


Create a room for designed for sleep: avoid bright lights and loud sounds, keep the room at a comfortable but low temperature. Try not to have a TV or a computer in your bedroom. The bed is for sleeping and intimacy only. Working from bed and watching TV creates strong associations in the mind that do not encourage deep, restorative sleep.

In the morning, expose yourself to bright (natural, if possible) lights to halt melatonin release. Avoiding sunglasses until lunch time has been shown to improve evening melatonin release and sleep scores.  


There is a reason why evolution forces us to sleep. Sleeping less than 7-9 hours a night impacts all aspects of our health, muscular, metabolic, and mental well-being. We must be disciplined with our sleep, like we do in other areas of your life. Set a sleep schedule, create an evening and morning routines, a perfect sleep environment and do your best from avoiding anything or anyone that encroaches on your non-negotiable 7-9-hour sleep opportunity each night. 

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