I'm now about at the half way point in the experiment I've set out to do with the "Carb Nite Solution" approach. You can read more about this experiment in my previous blog posts: Carb Nite Experiment and Carb Nite Experiment - First "Nite".
I've now done the "Carb Nite" 6 times, and I have some interesting effects to report. I've set out to do this for at least 3 months and then assess changes in my insulin sensitivity (as measured by my do-it-yourself glucose tolerance test) and average blood glucose (as measured by a home A1C test.) I've reported on my baseline measurements for these tests in the first post on this experiment. I chose 3 months as a target since the A1C is representative of an average blood glucose level over that period of time.
While it's too early to do follow up measurements to see the effects, I've made a few observations so far in this experiment.
I've generally aimed at a "standard american diet" (SAD) approach with a high level of carbohydrates and low fat (<30% of calories). I have not made any strong attempt to focus on "quality" of food in this experiment since this is aimed at changing macronutrient ratios and see the metabolic effects. While I haven't necessarily intentionally avoided quality foods, I've just found that it's a little more difficult to do while following the "SAD" for only a day a week.
Since i consume most of these meals during a regular work day, they've mostly been at area restaurants that are near work. They've included Noodles & Co. as mentioned in my last post, Amerigo (Italian restaurant), a local Mexican restaurant, and Panda Express (a fast-food Chinese restaurant.) I also managed to time my "carb nites" so that I would have one on Thanksgiving. (Hey, why not have some stuffing, mashed potatoes, fresh rolls, and pumpkin pie!)
Blood Glucose Impact
I've tracked the impact on my blood glucose for most the carb nites I've tried. I've found that the curve is very similar to the first time I tried it. I continue to see the high peak, lasting over 3 hours. I've included a composite graph of all the blood glucose tests I've done over the carb nites.
I've noticed that on the days when I would do the high carb meals I definitely felt over-full and bloated. I generally don't intend to overeat, but it's possible that I would be consuming more, either because I've tried to eat a lot of carbs, or because the carbs and the ensuing (intentional in this case) spike on insulin were driving overeating. In any event, I have definitely noticed a feeling of over-fullness after eating on these days.
I've noticed a return of some heartburn that I used to experience frequently before switching to a very low carbohydrate diet. Fortunately, I typically only notice it on the day I do the high carb eating, and I've not felt the need to take anything for it.
Perhaps the most pronounced effect I experience, one that the book predicts, is muscle cramping, particularly in my toes. This is probably the most notable observation that I made which confirm one aspect of the Carb Nite theory. Muscles (and the liver) store energy in the form of glycogen. As mentioned in other posts, humans can store about 2,000 calories worth of glycogen. When practicing a very low carb dietary approach, a significant portion (perhaps half) of that glycogen is depleted since the body doesn't need as much. The consumption of carbohydrates on "carb nite" triggers the body to store what it doesn't immediately need in the form of replenishing that glycogen. When glycogen in stored, each molecule of it is stored with 4 molecules of water. This means that this glycogen replenishment cause dehydration.
I was aware of this effect going in and have tried to stay hydrated, but found that these cramps occur surprisingly quickly. As I've done more carb nites, I've started hydrating sooner and have reduced the muscle cramps.
Normally I don't get muscle cramps in my toes. When I have at other times, usually due to some other electrolyte imbalance, I get cramping in my calf muscles. Why the glycogen replenishment would instead cause it in the toes is interesting. The only explanation I can propose is that since I'm intentionally trying to stay hydrating, and the glycogen replenishment seems to happen quite quickly, the toes are at the extremity and it's taking longer for the water to distribute out to them.
A reported benefit of this approach is that the consumption of carbs, especially in the evening, causes an increase in production of serotonin. Serotonin is the hormone that helps you feel good and helps to contribute to good sleep. I can definitely say that I've noticed this effect. At bedtime, when I'm doing the carb nite, I find that I'm very tired and ready to sleep. Much more so than when I'm not.
Another effect that the author reports is the feeling of increased body heat. This is supposed to be due to the excess carbs having to be burned, raising metabolism and thus body heat. I have not really observed this phenomenon.
Overall, the experiment is going well. I have been able to confirm some of the claims of the book but not others. The important effect that I'm looking for though, a positive effect on metabolic measures, I've not yet been able to assess. I'll do that after I've completed at least 3 months of the test. It is fun to have some of the "forbidden foods" from my normal, very low carb diet, but it's not something I would continue to do just for that reason. I don't really miss these foods and enjoy the high fat, low carb, whole foods that I normally eat.
From a health and weight standpoint, I've seen no benefits. In fact I "feel" like I'm less in-shape than before and that I've probably gained fat (although I've not measured any significant change so far.)