Carbohydrate Timing, Yay or Nay? Part One: PM Carbohydrate Consumption
The craze of nutritional timing and especially the craze, or obsession rather, over the extreme perfection of carbohydrate intake seems to be a forever, hot debate among bodybuilders and fitness professionals. Some “coaches” adhere to the strict rules of “no carbohydrates after a 6pm” or “no carbohydrates in your last meal”. Now there are some more “unconventional” believers that say carbohydrate timing is irrelevant, however, it is the overall daily amount that is the important or deciding factor in making or breaking your goals. There seems to be a little bit of science backing both sides of the argument. In this article I plan to evaluate both sides of each story and let you decide for yourself which one you think is best suited for you.
All that being said, it is ALWAYS important to, 1. Consider your personal goals and expectations with a particular diet or training plan and 2. Make a decision based on scientific evidence and facts (don’t be a drone!). Everyone’s goals and expectations will be different and also each person’s response to a particular dieting strategy will most likely be different. I always use the example of a man and a woman because it is most pronounced. A woman’s bodily response (whether she likes it or not) is going to respond differently to a higher carbohydrate diet opposed to man’s bodily response. This is in part due to the sex differences in carbohydrate metabolism but also more specifically in the individuals genetic predisposition and environmental factors effecting metabolic capacity. That said, lets delve a little deeper into some of the scientific factors of the late-night, evening, or PM carbohydrate intake.
First and foremost, when discussing carbohydrates we want to discuss the t
ype of carbohydrates (high glycemic vs. low glycemic) and the hormonal response that they both entail. Hormones are one of the most important factors if not the most important factor in weight gain/loss and muscular gains which I will elaborate more in depth on in later articles. However, for the purpose of this article we want to be concerned most with insulin and growth hormone and the effects that carbohydrates have on each. By first observing how carbohydrate type has an effect on hormones, we can then look at how timing of a particular carbohydrate might affect hormones differently. For the purpose of this article we are going to assume that your goals of carbohydrate timing would be to maximize muscular gains and simultaneously reduce the amount of fat gain. If your goals are otherwise, then your carbohydrate type and time intake may be different.
High glycemic carbohydrates are those that raise blood sugar quickly and induce a higher and more rapid release of insulin in order to control blood sugar and ultimately reduce blood sugar back to a normal range. Low glycemic foods on the other hand, have less effect on blood sugar and allow insulin to be reduced more slowly in order to control blood sugar. Most bodybuilding and fitness diets embrace the consumption of low glycemic foods for the very reason of insulin control. Continuously high blood sugar levels are conducive to fat storage and are, therefore, not traditionally used for weight loss or hypertrophy goals. That is not to say that one cannot benefit from eating any high GI foods, but in general consuming all high GI carbohydrates is actually not good for overall health.
So now that we have concluded that the majority of our carbohydrates should come from lower GI carbohydrates (or at least unrefined carbohydrates) lets look at why a timing variable is also questioned when trying to attain specific physique goals. One of the most important reasons for sleep as individuals, and bodybuilders alike, is the recovery and more specifically release of growth hormone during sleep. Growth hormone is actually sensitive to insulin (a hormone that’s fluctuations are mainly due to carbohydrate intake). That is with increased insulin, the release of growth hormone is suppressed. So why do you care? Well, growth hormone directly affects your goals of fat loss and indirectly affects your goals of muscular hypertrophy by affecting the release of igf-1(insulin-like growth factor); therefore, you want to maximize the natural release of growth hormone and adjust your dietary intake to have as little effect on the rise of growth hormone as possible.
However, it is important to note that insulin IS very much so needed to make muscular gains as will. Growth hormone and insulin alike are very anabolic hormones. That means they are both very important for building muscle and avoid catabolism. This was seen in some studies, which observed muscular growth in rats with no pancreas. Those rates that did not have a pancreas (resulting in no release of insulin with the consumption of carbohydrates) experienced less muscular hypertrophy than those with a pancreas. The possible reason for this is that insulin do
es deliver nutrients into the cell and allow for recovery. However, it may be that this is best manipulated to occur when it is interfering the least with growth hormone when it is at its highest levels. This being said, the prime example of why those who are on a low carbohydrate diet eventually plateau or cease to see any kind of gains is demonstrated; they are essentially lacking the nutrients that the muscle needs for recovery and thereby to produce hypertrophy. It is also important to note that when speaking about insulin and PM carbohydrate consumption, it will be important to be aware of the particular time of training of an individual in comparison to his/her actual bedtime. It will be important (as some may believe) to consume a higher carbohydrate meal post workout. If training was performed in the evening closer to bedtime than the average individual, it still may be of importance to consume the higher carbohydrate post workout meal because of the relationship to the time of training, more importantly than the time of carbohydrates prior to sleep.
The reason lots of coaches adhere to the “not carbs” at night rule is that their thinking reflects that of a slowed metabolism in the evening hours. This is a belief that has no true grounding in any scientific origins. What may be most important about PM food consumption as opposed to only carbohydrates is the amount of food upon bedtime in total. Ghrelin, the hormone that is released by your body when you are hungry, actually MUST be present for the release of growth hormone in the body. Like we said before, growth hormone is absolutely needed for recovery from any type of exercise. All that being said, it may be beneficial to have your last meal at least one hour to one hour and half before you go to bed. It may not be isolated to only carbohydrates at night in terms of growth hormone release.
In conclusion, it seems there have been scientific origins to both carbohydrate consumption at night and absence there of. It is specific to each individual and also the combination of other factors such as type of macronutrients being consumed, relationship of training time to sleep, and presence of absence of other hormones that can optimize growth hormone release. All in all, it will be important to see your personal factors and establish whether you believe carbohydrates in the evening are necessary for your particular body and goals.
Sources and Photo Credits:
Michaels, Jillian. Master Your Metabolism. New York: Three Rivers Press, 2009. Print.
Nass, Ralf. M., Bruce Gaylinn, Alan Rogol, and Michael Thorner. "Ghrelin and growth hormone: story in reverse ." Proceedings of the National Academy of Sciences of the United States of America. 107.19 n. page. Print.
Xu, J., and J. Messina. "Crosstalk between growth hormone and insulin signaling." Vitam Horm. (2009): 125-153. Print.
Joseph, Messina, Shaonin Ji, Ran Guan, and Stuart Frank. "Insulin Inhibits Growth Hormone Signaling via the Growth Hormone Receptor/JAK2/STAT5B Pathway." Journal of Biological Chemistry. n. page. Print.
http://www.joyamartin.com/carbohydrates-matter/
https://en.wikipedia.org/wiki/Growth_hormone
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