Sleep is essential for fat loss, and by sleep, we mean both duration (7-9hours) and quality (falling asleep quickly and staying asleep).
While it may not necessarily have a direct affect on fat loss, sleep affects a multitude of factors relating to optimal fat loss. One study showed that sleep deprivation decreased amount of weight loss from fat by 55% AND increased loss of fat-free mass (from water and/or muscle) by 60%.
Less fat loss and more potential muscle loss?
So how does sleep impact fat loss?
As we know, training is one of our main factors for muscle retention during a dieting phase. Good sleep will positively impact performance, as well as the resulting recovery from the training.
This will ensure more effective training in terms of load/volume used, to ensure muscle retention, as well as training for longer periods of time and more cycles of training before requiring deloads.
As we defined previously: stress is a stimulus that disrupts our mental or physical equilibrium. In addition, we discussed stress being a prerequisite for adaptation such as fat loss whereby these adaptations can be positive or negative depending on the management and counter-measures of these stressors.
Our most powerful counter-measure to ensure recovery from stressors, and therefore producing positive adaptations, will be…
Yes, you guessed it…
Sleep deprivation, which can be defined as less than 6 hours of sleep has been shown in research to have negative consequences on insulin sensitivity and glucose clearance.
Why does that matter?
Insulin helps to control the level of glucose (carbs/sugar) in the blood. A reduction in insulin sensitivity leads to cells not absorbing as much of the consumed glucose, which can lead to elevated blood sugar levels.
As a result, the body cannot efficiently utilise the carbs consumed to be used as fuel, and therefore affect our ability to burn body fat.
Reduced sleep, with regards to quality and duration has been shown to have a significant increase in appetite, in particular for fatty-foods.
What do we mean by significant…well looking at some numbers from the research:
The potential mechanisms for these factors are:
Reduced leptin levels - influencing satiety signalling, therefore potentially increasing appetite, reducing feeling of ‘fullness’ and affecting adherence to a calorie deficit.
Increased ghrelin levels - influencing hunger signalling, therefore potentially increasing appetite, and facilitating retention of fat.
Elevated cortisol around bed time - potentially affecting stress and inflammation.
While fat loss may seem as simple as creating a calorie deficit…there’s so many factors affecting, masking or blocking the execution of implementing a deficit, that we must consider and manage them to ensure an efficient fat loss program.