You snooze you lose! Or gain?

Sleep plays a huge part in our ability not only to exercise but to function throughout the day. It seems like an obvious and fairly basic comment but we underestimate the effect lack of – or indeed too much – sleep can have on our ability to exercise effectively and safely.

Sleep and Diet

It’s an undoubted and unrivalled privilege to get a good 8 hours of uninterrupted sleep, and it seems that a huge 35% of people are in fact diagnosed as sleep deprived (Centres for Disease Control and Prevention). The idea that sleep has an impact on diet was actually put to the test by researchers within Internal Medicine that tested 2 groups of dieters who were put on different sleep cycles; those receiving adequate sleep lost weight- half of which was fat. Those lacking in sleep discovered that the amount of fat they lost was halved in comparison- regardless of the food consumed. The second group also independently complained of lack of energy to exercise as well as a greater keenness to eat more. To put a figure on it- the study showed that sleep deprived dieters experienced 55% less fat loss than those well-slept.

So, aiming for between 6 and 8 hours’ sleep is fuel enough for the body to achieve its greatest potential at weight loss.

Sleep and exercise

Often, I find myself speaking to gym goers and fitness first-timers who report that with even a minor increase in their physical output daily, increases their ability to get a good night’s sleep. As little as 10 minutes of aerobic exercise, such as walking or cycling, can dramatically improve the quality of your night-time sleep.

As exercise reduces stress and tires you out, exercising earlier on in the day can allow you to motivate yourself to get it out of the way early as well as the benefit of increased calorie burn throughout the duration of the day. A study even suggested that those exercising on a treadmill at 7am could sleep longer, experience deeper sleep cycles, and spend 75% more time in the most reparative stages of sleep than those who exercise at later times that day.

However, it is a misconceived idea that exercising later in the day is a negative stimulus for sleep as it can over-excite the body and interfere with your ability to get to sleep. However, this is not strictly true; the body’s resting temperature is always marginally higher in the afternoon creating a positive effect on our muscles and their capacity to train more efficiently. The knock-on effect of the later exercise is that as your core temperature decreases, the body will begin to shift into sleep mode which should in turn aid a good night’s sleep.

So, we can conclude that perhaps it is a trial and error for your body to experience both exercise schedules and determine which creates the greatest energy output as well as sleep success!

Sleep and Fat

Believe it or not, your fat cells can also experience fatigue like the rest of your body. ‘Metabolic grogginess’ is a term given to individuals who are suffering from 4+ days of sleep debt- or simply just 4 nights of poor sleep. This change in your body’s equilibrium has a huge effect on your hormones, especially insulin (a fat-storing hormone). When the body functions efficiently, insulin aids in the removal of fatty acids from the blood stream. However, the body’s ability to do this when tired greatly reduces- this is called insulin resistance. So, the body cannot process carbs and sugars like normal. Excess insulin is pumped into the blood which in turn stores fat and can lead eventually to diabetes with increasing fat around vital organs such as the liver.

The good news is that insulin resistance is easily reversible with the right food choices and good sleep cycles.


The ideal way to combat this fatigue with food is to eat lower carb foods when feeling tired in order to stabilize blood sugar levels and sustain your body’s energy levels for the day. Protein snacking can also aid in the prevention of the afternoon slump on tired week day afternoons- nuts and seeds work a treat!

So with all of the above taken into consideration, we can see there is a strong connection between sleep, weight and general wellbeing. Take away from this the following statistic:

‘Women who are sleep deprived are a 33% more likely to gain 2 stone over the next 16 years than those who receive just seven hours of sleep a night’ - American Journal of Epidemiology.

The best foundations for positive progression with fitness and health is a solid 7+ hours’ sleep to fuel yourself for exercise and better your chances of both healthy diet and living.