Over the past 30 years, research into sleep and metabolism has been uncovering a very interesting (and pleasantly surprising!) truth: to achieve our best physique, we need to be sleeping more! In fact, loss of sleep may be a major factor in weight gain, or difficulty with weight loss. Why is this? We all know we don’t feel great when we haven’t slept enough; but why should it affect our body composition in any way? Let’s check out a few reasons.

Sleep & Your Hormones

Body composition, weight loss and weight gain are regulated by hormones. Hormones are essentially chemical messengers that tell our body what to do in response to stimuli. During our waking hours, hormonal levels ebb and flow in response to the stimuli we provide: eating, training, work are all examples of the typical stimuli of a regular day. To be lean, healthy and toned, we want our system to be hormone-sensitive. This means that for a given stimulus, we only need a tiny bit of hormone release to get the job done.

Let’s take insulin as an example, because it’s a major player in weight management. In response to eating a meal, an insulin-sensitive person will produce much less insulin compared to a person with lower sensitivity. Insulin is primarily a storage hormone, so the more insulin is produced the more likely we are to store what we’ve eaten. In other words, an insulin-sensitive person is much less likely to gain weight, and will find it much easier to lose weight, compared to a person with lower sensitivity. Insulin, together with a few other hormones, also plays a massive role in food cravings, especially for sugar. We all know how much cravings drain our willpower: improving sensitivity to these hormones could help eliminate cravings completely. So how does sleep come into this picture? Restful sleep can make us more hormone-sensitive because it can reset how well we ‘hear’ hormonal messages.


Sleep also affects cognitive ability, decision-making skills and willpower. When we sleep less, we are more likely to overeat, comfort eat, and make poor nutritional choices. By getting enough sleep, we don’t just improve our ability to hear our hormones better (which removes a huge chemical and metabolic barrier to weight loss), we also improve our ability to hear ourselves better – to make better choices, to keep up motivation and to sustain positive action.

There’s more to lack of sleep than just feeling a bit crabby and irritable. Securing those 7-8 hours a night for yourself puts you in the best chemical, physical, mental and emotional space to achieve your best physique.

words by Martina Avellino – PhD RTS

image hush-uk