By Stefan Ianev 

Should you really not eat before bed?

Whether or not you should eat before bed is another ongoing debate amongst fitness enthusiasts. Some people claim that eating before bed blunts growth hormone (GH) release, while others claim that eating before bed offsets overnight catabolism. 

So, who is actually right? Well, as with most things: it really depends on the person’s 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 [1]. 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. Genetic factors also come into 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 [2]. 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 susceptible 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 an 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 should be before 7pm. Several studies have shown that early time restricted feeding can lead to reduced energy intake and aid weight loss. Some studies have also 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 of weight loss [9,10].

However, this feeding pattern is not suitable for everyone, particularly night owls or evening chronotypes. That’s because in these individuals, elevated melatonin levels may persist for longer in the morning, which increases the metabolic risk, due to decreased glucose tolerance [2].  

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. 

In conclusion, there is no one size fits all approach, and you should experiment to see what works best for you!

References

1. Res PT, et al. Protein ingestion before sleep improves postexercise overnight recovery. Medicine & Science in Sports & Exercise. 2012;44(8):1560-9. 
2. Lopez-Minguez J, Gómez-Abellán P, Garaulet M. Timing of Breakfast, Lunch, and Dinner. Effects on Obesity and Metabolic Risk. Nutrients. 2019;11(11):2624. Published 2019 Nov 1. doi:10.3390/nu11112624
3. Nas A, et al. Impact of breakfast skipping compared with dinner skipping on regulation of energy balance and metabolic risk, The American Journal of Clinical Nutrition, Volume 105, Issue 6, June 2017, Pages 1351–1361, https://doi.org/10.3945/ajcn.116.151332
4. Varady KA. Meal frequency and timing: impact on metabolic disease risk. Curr Opin Endocrinol Diabetes Obes. 2016 Oct;23(5):379-83. doi: 10.1097/MED.0000000000000280.
5. LeCheminant JD, Christenson E, Bailey BW, Tucker LA. Restricting night-time eating reduces daily energy intake in healthy young men: a short-term cross-over study. Br J Nutr. 2013;110(11):2108‐2113. doi:10.1017/S0007114513001359
6. LeCheminant JD, Christenson E, Bailey BW, Tucker LA. Restricting night-time eating reduces daily energy intake in healthy young men: a short-term cross-over study. Br J Nutr. 2013;110(11):2108‐2113. doi:10.1017/S0007114513001359
7. Ravussin E, Beyl RA, Poggiogalle E, Hsia DS, Peterson CM. Early Time-Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity (Silver Spring). 2019;27(8):1244‐1254. doi:10.1002/oby.22518
8. Carlson O, Martin B, Stote KS, et al. Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metabolism. 2007;56(12):1729‐1734. doi:10.1016/j.metabol.2007.07.018
9. Sutton EF, Beyl R, Early KS, et al. Early Time-Restricted Feeding Improves Insulin Sensitivity, Blood Pressure, and Oxidative Stress Even without Weight Loss in Men with Prediabetes. Cell Metabolism. 2018 Jun;27(6):1212-1221.e3. DOI: 10.1016/j.cmet.2018.04.010.
10. Jamshed H, Beyl RA, Della Manna DL, Yang ES, Ravussin E, Peterson CM. Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans. Nutrients. 2019;11(6):1234. Published 2019 May 30. doi:10.3390/nu11061234
11. Moro T, Tinsley G, Bianco A, et al. Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational Medicine. 2016;14:290. doi:10.1186/s12967-016-1044-0.
12. Stote KS, Baer DJ, Spears K, et al. A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults. Am J Clin Nutr. 2007;85(4):981‐988. doi:10.1093/ajcn/85.4.981