As the Paleo diet becomes more popular and people give it a whirl, it's important to understand that many early versions that were low carb presented problems for some people, especially people who were training hard in exercise modalities that primarily use glucose for fuel such as Crossfit. One of the more common experiences under this scenario is waking up between 2am-4am, often times with heavy heart pounding. This phenomenon can be explained and potentially remedied using what we know about blood glucose regulation and what I went over in my last 2 blogs found here and here on allowing the intestine to help the liver with blood glucose regulation.
Now, there is a simple fix, eat more carbohydrates; and you should probably do this over the long term anyway if you are training hard. There is a solution that you can use during short term low-carb dieting to lose weight or if you want to stick to a low carb diet over longer periods. But first, let's take a look at what may be happening to wake you up.
The modern Western diet, being high in carbohydrate and low in fiber, relies heavily upon the liver to regulate blood glucose levels. While it is pretty good at doing it's job, not providing carbohydrates to help it do it's job can make blood glucose regulation difficult. To help your liver keep pace, glucagon and epinepherine levels rise in the blood to communicate to the liver that it needs to release some of the glucose it stores as glycogen, provided it has stored up enough glycogen from the carbohydrates you consume and made enough glycogen from non-carbohydrate sources. But what happens if there is not enough glycogen stored in the liver to keep blood glucose above the critical level?
When you are up and moving around, muscles break down glucose in to lactate that the liver can use to make glucose via a process called the Cori cycle. This likely contributes to blood glucose regulation while you are awake. The interesting thing here is that epinepherine, more commonly known as adrenaline, causes muscle to break down glucose in to lactate and activates the Cori cycle(1). As you may know as well, adrenaline also rapidly increases heart rate and the force of contraction of the heart. Could the 2am low carb wake up call be due to blood glucose levels dipping too low and the adrenals correcting this issue by secreting epinepherine? This could certainly explain why people get woken up and experience a pounding heart. If this is the case, there is a simple correction that should remedy the situation. Remove some of the burden of blood glucose regulation on the liver by allowing the intestine to participate. In other words, increase your fiber intake.
Most Americans get less than 20g of fiber per day and a person who is undertaking a low carbohydrate diet likely gets less if they are avoiding vegetables. Bumping this number up to 60g or more could potentially help a person who wishes to maintain a low carbohydrate diet not have to worry about large drops in blood glucose. Optimally the fiber would come directly from the diet, but you could also take a fiber or resistant starch supplement to get your daily fiber intake up. Many people are taking Bob's Red Mill unmodified potato starch as a supplement to increase fiber intake, just start with a low dose and space out your intake throughout the day to prevent gas. You can work up to 4 tbsp per day which adds approximately 32g of resistant starch/fiber per day.
It may take a while to see significant improvements, especially in people who may not have a large amount of bacteria that ferment fiber/resistant starch in to the short chained fatty acids that help the intestine participate in blood glucose regulation. Be persistent and, most of all, pay attention to what your body is telling you. Gas tends to be a good thing, but if it becomes painful or smells putrid you may have to take it slower.