For the last four years I have been telling my clients and my friends that it is okay to eat carbohydrates at night, but I was wrong. In the last year, I have changed my advice about carbohydrates completely. In the past I believed carbohydrates were the culprit for the obesity epidemic and that we should be eating them at night versus the morning. Unfortunately, I was wrong and I am not ashamed to admit it. Based off my current research I believe we should be eating our carbohydrates in the morning and throughout the day. Personally, I do best if I stop eating my carbohydrates by 7pm. I used to eat the majority of my carbs at night and I slept well and wake up feeling refreshed. But then one day I was listening to a podcast and learned that melatonin (read more here) inhibits the body's ability to use insulin. And since carbohydrates secrete insulin, I figured it would be a good idea to limit my carbs to the daytime only.
When I limited my carbs to the daytime only, I slept much better and woke up with even more energy than I could have ever imagined. My mind felt clear and focused. So this sparked my curiosity and for the last couple of months I have been digging into this insulin-melatonin relationship. And here's what I have found...strap in, we are about to get nerdy!
Generally speaking, f the body wants to create melatonin it needs adequate levels of the amino acid tryptophan. Once there are adequate levels of tryptophan in the body and the eye receives dim light (i.e night time) then the tryptophan will convert into the neurotransmitter serotonin which then gets converted into melatonin.
(Need a brush up on serotonin? Click HERE!)
Here's the interesting thing, serotonin is also found in the pancreas and directly influences insulin production(1). And as a Rokiskyfitness reader, you know that the body needs time for certain neurotransmitters and hormones to recover ( i.e serotonin converting in melatonin). Since serotonin directly influences insulin secretion, once it gets converted into melatonin the body will then lose its ability to secrete insulin i.e melatonin inhibits insulin production (2). And if you think about it from an evolutionary standpoint it makes total sense. Before agriculture and electricity, most of the eating was done during daytime. Most of the time, humans would be in a fed state during day time and a fasted state during the night. Which led to high insulin levels in the day versus low at night.
As you go even deeper into the process of how the body creates serotonin it starts to make even more sense. When insulin is secreted due to carbohydrate, protein or fat intake, insulin opens the cells and allows the body's amino acids to enter into those cells. This process allows higher levels of tryptophan in the body which makes it easier for it to convert into serotonin. In my opinion, the body does this on purpose to make sure it has adequate levels throughout the day to function properly. Furthermore, exercise aka movement increases tryptophan levels in the body due to the breakdown of muscle. When muscle is broken down (exercise) it uses amino acids (protein) for recovery and growth which then allows higher levels of tryptophan in the body and this is why exercise, specifically aerobic (running, walking), makes us feel so damn good. To sum up, the body has a series of feedback loops to make sure that the body has adequate levels of serotonin throughout the day. As the day progresses, these feedback loops slowly start to run out of energy and eventually need recover. This is when serotonin will convert into melatonin because melatonin is one of the strongest antioxidants in the human body and helps aid in its recovery by clearing out the free radicals that were produced throughout the day. (3)
Are you still with me?
Here's a quick summary...serotonin directly controls insulin production throughout the day, but needs time to recovery due to reactive oxygen species (ie byproduct of energy production). This need for recovery starts the conversion of serotonin into melatonin. And since serotonin controls insulin production, this means that melatonin will inhibit insulin production so that the body can recover. But here is the most fascinating thing, a study published in Cell Metabolism found the following:
"Up to 30 percent of the population may be predisposed to have a pancreas that's more sensitive to the insulin-inhibiting effects of melatonin, a circadian rhythm hormone. People with this increased sensitivity carry a slightly altered melatonin receptor gene that is a known risk factor for type 2 diabetes."
The study suggests that one in three people will be affected differently by carbohydrates at night. This means that people who carry this gene need to limit their carbohydrate intake and protein intake at night due to higher melatonin levels which would lead to higher blood glucose levels. Nevertheless, the body is extremely complex and only time will tell if my hypothesis is correct. But you don't have to wait for a genetic test, you can test it out on yourself. All you have to do is stop eating your carbohydrates by seven or eight o'clock at night and see how you feel the next day.
* Also people with this gene should not be taking a melatonin supplement