By Stefan Ianev
Whether or not you should eat before bed is another ongoing debate amongst fitness enthusiasts with some people claiming that eating before bed blunts growth hormone (GH) release, while other claim that eating before bed offsets overnight catabolism.
So, who is actually right? Well, as with most things, it really depends on the persons goals and their unique physiology.
Studies have indeed shown that consuming a slow-release protein such as casein before bed may promote a more favourable anabolic response during the night . Therefore, if maximum muscle growth or muscle retention is your primary goal, that is a strategy that you might want to consider.
However, there is more to it than that. There are also genetic factors at play which will determine whether an individual will respond adversely or not to eating too close to bedtime.
Apart from regulating the sleep-wake cycle, the hormone melatonin has been shown to impair glucose tolerance in about 50% of the population . It appears that this is linked to a melatonin receptor polymorphism.
In susceptible individuals, eating the bulk of calories later in the day, when melatonin is elevated, has been shown to increase the risk of obesity, dyslipidemia, hyperglycemia, inflammation, and metabolic syndrome [2-4].
So, how do you know if you are a suspectable individual? Well, without genetic testing it is impossible to know for sure, however, it is worth experimenting with not eating before bed to see if it makes any difference for you.
Furthermore, if you are a susceptible individual, the length of time you would need to leave without eating before bed would depend on your chronotype.
For example, some people are naturally early birds or early chronotypes which means they have early onset of melatonin (around 7pm). Late chronotypes or night owls have late onset of melatonin (around 1am), while neither-types have melatonin onset around 10pm.
Therefore, if you are an early bird, your last meal would be before 7pm. Several studies have shown that early time restricted feeding can lead to reduced energy intake aid weight loss, and some studies have shown that consuming the bulk of daily calories in the evening may lead to elevated fasting glucose levels, and impaired morning glucose tolerance [5-8].
Additionally, some studies have shown that early time restricted feeding can improve insulin sensitivity, blood pressure, and oxidative stress, and may also increase autophagy and have anti-aging effects in humans, irrespective or weight loss [9,10].
However, this feeding pattern is not suitable for everyone, particularly night owls or evening chronotypes, because in these individuals, elevated melatonin levels may persist for longer in the morning, which increases the metabolic risk, due to decreased glucose tolerance .
These individuals may actually respond better to late time restricted feeding as it is more aligned with their circadian timing. Several studies have reported a modest improvement in fat loss when consuming the daily calories later in the day, even when consuming the same total calories [11,12]. Therefore, night owls may be able to get away with eating a little bit closer to bedtime and pushing out their breakfast a bit.
The take home point is that there is one size fits all approach, and you should experiment to see what works best for you.