The paleo diet in and of itself is not a “high-fat, low-carbohydrate” diet; however, many people utilize paleo thinking as a method of achieving a low-carbohydrate way of eating. The paleo meal plan I’m currently using is based on that method. One of the premises of high-fat, low-carbohydrate is that your body enters into a state of ketosis. That means that your body is switching fuels from using primarily carbohydrate to mainly fat.
Remember in this post when I talked about how your body breaks down carbohydrates to use for energy? Well, here begins chapter 2: After your body turns the carbohydrates into glucose and your cells pick up the glucose, a bunch of active little proteins called enzymes start changing the glucose by adding and taking away chemical bonds. At the end, the glucose is converted to something called Acetyl CoA which then goes on into another process known as the TCA cycle (or Kreb’s cycle, or citric acid cycle, but that’s neither here nor there). This nifty little pathway is the major energy factory in your body. In fact, my metabolism textbook* says that “over 90% of the energy released from food is estimated to occur as a result of TCA cycle oxidation.” Basically, it’s where carbs, fats, and proteins all go to die. They are broken down until there is just water, carbon dioxide, and energy left. Pretty cool, huh?
Since Paleo is considered a high-fat diet, I’ll start with fat. After making its way into the cells, the fatty acids undergo a conversion to (guess what?) acetyl CoA. That molecule then has two possible destinations: it can either go through the TCA cycle just like the former glucose molecules do, or in the presence of extra acetyl CoA the liver can convert it into something called ketones. Ketones can then travel throughout the body to other tissues where they are actually converted back into acetyl CoA and used for energy there.
Starting Wednesday morning (paleo day #3), I started having hot flashes, brain fog, nausea, lightheadedness, and a mild headache. All of these are symptoms described by paleo-diet promoters as the “low-carb flu”. Others complain of such maladies as muscle soreness, extreme fatigue, poor sleep, and digestive disturbances. Doesn’t that just sound like a barrel of monkeys?
Anyway, these ailments are due mostly to chemical shifts in my body (that are super complicated) and the adjustment from using well-oiled glucose burning machinery to my dusty, rusty fat/ketone users. Most of my symptoms have gone away by now, but I now have a bad taste in my mouth (all the time) and occasional hot flashes. My next quest is to investigate the long-term implications of this way of eating and how it affects the body over time. Here goes nothing!
*Gropper, Smith, and Groff. Advanced Nutrition and Human Metabolism. 2009. 5th edition. Wadsworth, Cengage Learning. Belmont, CA.
UPDATE (3/1/14): A friend of mine made a good point that prompted me to edit the original post. I had originally referred to the paleo diet as a high-fat, low-carbohydrate diet, but paleo in and of itself is not “high-anything” or “low-anything.” If one wanted to not eat a low carbohydrate diet and still be paleo, he or she could eat loads of fruit, for example. In my case, the meal plan I chose only included fruit 3 times in the first week, so I have ended up on a high, fat low carbohydrate diet though paleo would not necessarily require that. I updated the post above to reflect this.