It’s now well known that if you are trying to lose weight, apart from being more mindful of what you eat and taking regular exercise, getting a good night’s sleep is an essential part of an effective weight loss programme.
In fact, the relationship between sleep and bodyweight is bidirectional. Studies have shown that when we lose sleep we gain weight and that those who are overweight or obese tend to sleep less too.
In this post, I will explain why lack of sleep makes us hungrier and crave unhealthy foods. I will also explain why we find it a lot harder to achieve our target weight loss from our fat stores when we are sleep-deprived.
Indeed, one study involving participants exercising, dieting and changing sleep hygiene showed that those increasing their sleep had a higher reduction in body fat when dieting than with less sleep. In % terms, there was a 75% improvement in fat loss than those who were underslept.
The relationship between sleep & weight gain.
Before we explore the relationship between sleep and weight loss, it’s perhaps easier to understand the mechanisms behind why we gain weight when we lose sleep.
Virtually all the worldwide epidemiological studies examining the association between sleep and obesity in adults and children have found that short sleep (generally <6 h per night) and was related to increased obesity risk.
In one analysis it was suggested that a reduction in 1 hour of sleep per day would be associated with a 0.35 kg/m2 increase in BMI. For a person approximately 178 cm ( 5 ft 8 inches) tall that would be equivalent to a weight gain of approximately 1.4 kg (3.1 lbs).
In studies using experimental sleep restriction, sleep deprivation was associated with increased levels of ghrelin, salt retention and inflammatory markers as well as decreased levels of leptin and insulin sensitivity.
Ghrelin is a peptide that plays an important role in short-term appetite regulation, whereas leptin is a factor that controls long-term energy balance and is considered a satiety hormone.
Thus, with increased appetite, and decreased satiety during sleep loss we are inclined to eat more when sleep deprived. In addition, as we are awake for longer, we have the opportunity to eat more. Here, a study in the American Journal of Clinical Nutrition showed when we lose sleep, late-night snacking increases. In addition, these snacks tend to be high-carb based.
Sleep and food choice.
The reason for this is that apart from affecting the hormones which control appetite lack of sleep also affects the endocannabinoid system. This system amongst others is involved in the regulation of appetite, sleep and mood. When it is out of balance with lack of sleep, the endocannabinoid system stimulates us to seek out ‘pleasure eating’. This involves eating more sweet food, heavy carbs and fatty foods. The problem here is that this type of diet adversely affects sleep, which in turn leads to sleep deprivation and even more sugar cravings.
Sleep and weight loss.
One of the main problems with trying to lose weight when we are underslept is that find it harder to lose weight from our fat stores. A study by the University of Chicago showed that with a restricted diet, whilst weight loss for those underslept was the same as those with adequate sleep, those with poor sleep lost 70% of their weight from lean muscle mass, yet those who slept well had over 50% of weight loss from body fat. Here when we are sleep deprived we into fight or flight mode. Holding onto our fat stores is seen as part of this crisis where our access to instant energy becomes vital to survival.
Our typical approach to weight loss is to limit calories by reducing processed carbohydrates and fats and doing some exercise. However, if you want your weight loss to come off your fat stores getting a good nights’ sleep is vital.
Diet and Sleep.
So what and when should we be eating?
Whilst there are a number of specific foods which are regarded as great for sleep, studies have shown that in the long term a ‘Mediterranean’ diet is the best option ( as with all health). This diet is based on increasing fruit and vegetable intake, choosing whole grains (higher in fibre), and favouring vegetable oils (low in saturated fat)
Be mindful too of eliminating food groups and make sure you eat a wide range of foods to get all of the essential vitamins and minerals. A recent study showed that difficulty maintaining sleep was associated with fewer foods in the diet, with daytime sleepiness and less none restorative sleep being associated with being on a restricted diet, such as low fat/cholesterol.
In terms of timing, it’s important to eat lighter meals in the evening, as heavy meals close to bedtime lead to sleep loss. Ideally, eat at least three hours before you plan to sleep.
Don’t let fatigue interfere with your motivation.
Finally, the benefits of being rested and staying fully motivated should also not be underestimated. As Dr Iuliana Hartescu, of Loughborough University’s Clinical Sleep Research Unit, states in her new year message,
“When you’re more rested you’re more likely to be physically active, more likely to eat at the right times of the day, and you’re more likely not to let fatigue interfere with your motivation to stick to your diet.”