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.

As I’ve been focusing on carbohydrates in my research thus far, I wanted to build a “foundation of physiology”, if you will, to build all the dietary recommendations on. If you’re a science geek, I hope you’ll enjoy this with me. If you’re not a science geek and you’d rather mow grass with fingernail clippers than read about the way your body works, stop reading and come back tomorrow. I promise to post a delicious new recipe for you then. Now, on to the nitty-gritty.

Carbohydrates are the primary source of energy in grains, fruits, dairy, starchy veggies (potatoes, beans, etc.), and sugar. Depending on the type of food, the carbohydrates are either long chains of molecules (complex carbohydrates), or short chains or single molecules (simple carbohydrates). Once you put these in your mouth, your body gets right to work. An enzyme in your saliva starts breaking the bonds between the molecules. It usually doesn’t get very far, because most of us swallow before it has a chance to break all of the chains apart. My sixth grade science teacher used a neat trick to demonstrate this breakdown by giving us each a saltine cracker and told us to chew on it for at least a minute. Eventually, it started to taste sweet because the carbohydrates were being broken down into their individual sugar bits…pretty neat, huh?

Anyway, then you swallow and the food goes into your stomach. Not much happens here in the way of breaking apart the carb chains, because your stomach contents are too acidic for the enzymes to work. After your stomach has done its thing, the food passes into your small intestine where most of the magic happens. Another enzyme (dispatched from your pancreas) goes to work breaking the rest of the bonds in the chains of carbohydrates. You are basically left with single molecules known as monosaccharides. You may be familiar with their individual names: glucose, fructose, and galactose. I’m only going to talk about glucose for now, because that’s the most prominent player in your energy pathways. Glucose molecules are transported into your intestinal cells and then pass from there into your blood through a variety of methods. If you have ever heard of someone testing their blood glucose or their blood sugars, they are essentially measuring how many of these glucose molecules are floating around in their blood at any given time. Some of the glucose then goes to the liver for storage, and some of it needs to get into your body’s cells to provide you with energy. To get out of the blood and into most of those cells, glucose needs help from a hormone called insulin.

Think of the glucose molecules in your blood as people walking on the street, and the cells of your body as locked houses. The glucose can’t get into the houses without a key – in this case, insulin (as you can see in my highly sophisticated diagram above). Once it’s in your cells, it can either be used to make energy right away, or stored away in long chains called glycogen until your body needs energy later.

If there is more glucose left over when all of your body’s glycogen stores are full, then your body converts the glucose into fatty acids and stores it away as body fat. Furthermore, that extra glucose actually tells your body to use less of your body’s stored fat for energy. Now before you go scolding your body for this process, remember that it came from the survival instincts of our ancestors who often lived in times of either feast or famine. While there was plenty to eat, their bodies stored fat to sustain them in times of hunger. The problem for many modern-day people is that they constantly live in times of plenty. When people go on low-calorie weight-loss diets, their bodies will start to use that fat (and unfortunately, muscle) to fuel them. Now I’m definitely not advocating that we all just run off and haphazardly quit eating carbohydrates to lose weight. There are definitely pros and cons to be weighed, and for now I’m an advocate of age-old moderation. In agreement with the information I referenced in previous posts, my textbook on metabolism states that (as of 2009) researchers have yet to determine the ideal balance between carbohydrate, fat, and protein intakes for fat loss. Clearly, there is a balance to be achieved.

So there you have it – a snippet of your body’s complex innerworkings. Maybe now you and your body will have more to talk about!

You may or may not know that energy provided through our diets (measured in calories) comes primarily from three different substances called macronutrients. If you’re not sure what they are, I’ll give you a hint – check the post title! Carbs and proteins each provide 4 calories per gram and fats provide 9 calories per gram. I mentioned on Monday that the MyPlate diet was leaning me in a more carb-a-licious direction than I’m used to. Left to my own devices, I tend to focus more on protein in my diet. For healthy adults, the Dietary Guidelines recommend that 45-65% of our calories come from carbohydrate, 10-35% from protein, and 20-35% from fats. Here’s an analysis of what I ate Monday and Tuesday on the MyPlate diet meal plan:

My fat intake for yesterday crept up because I chose to use my discretionary calories on cookie dough ice cream (yum!), but you can see that I’m still within the ranges for everything based on the plan. That’s all well and good, but where do these percentages come from?

An excellent question. The ranges are based on the Dietary Reference Intakes (formerly known as the Recommended Dietary Allowances) created by the Institute of Medicine. The process for creating these is similar to that for creating the Dietary Guidelines: experts, committees, research, deliberation, gigantic reports, and finally, the guidelines themselves. The guidelines represent what the experts have determined to be a safe, healthful, and adequate intake of any given nutrient. Each macronutrient plays a different role in the body.

• Carbohydrates are anything that can be broken down into sugar in the body. Most of that sugar ends up in the form of glucose, which is processed to create energy.
• Proteins are often referred to as “building blocks”. They make up the cells of the body and act as transmitters and transporters. If dietary carbohydrates are restricted, they can also be used for energy.
• Fats provide a concentrated form of energy as well as components of hormones and other vital goodies. They also provide a medium for delivering fat-soluble vitamins to our tissues.

Since it is the first thing I noticed about my newly-adopted menu (and for the sake of not deluding myself to think you’d read 10,000 words on macronutrients), I am looking into the carbohydrate recommendations first. According to a report by the Institute of Medicine, the recommendations for carbohydrates are a range between the minimum amount of carbohydrate needed to provide fuel for the brain and maintain weight and a maximum recommended amount to prevent weight gain and decrease risk of chronic disease. It goes without saying that obesity and the loads of diseases associated with it are a significant problem in our country, so I looked further into the weight aspect of the recommendation.

We have all heard of low-fat, low-carb, or high-protein diets being promoted for weight loss. Just for context, the “low” and “high” qualifiers here are in reference to intakes that are outside of the recommended ranges I mentioned earlier. In the Dietary Guidelines 2010 Report, the authors wrote that “no optimal macronutrient proportion was identified for enhancing weight loss or weight maintenance” and that “there is strong and consistent evidence that when calorie intake is controlled, macronutrient proportion of the diet is not related to losing weight.” Two paragraphs later, however, they reported that twenty research studies showed no difference in macronutrient proportion for weight loss, thirteen showed that low-carbohydrate diets were more effective than either high-carbohydrate or low-fat diets, and six showed that high-protein diets were more effective than low-protein diets. So you might be having the same issue I am here – what is strong and consistent about the evidence? Nearly HALF of the total studies included are in disagreement with the conclusion. Now granted, not all research studies are created equally. The DGAC has a scoring system that rates the impact of the study based on the quality of the research, which may have led certain studies to be considered more relevant than others. Still though, I’ll have to look into the research articles myself a little more to see how it all really pans out.

In other news, I begin my traveling tomorrow to visit my friend Abbie in Lake Tahoe for a weekend snowboarding excursion. As I will be continuing my diet through the trip I informed her ahead of time of my situation. Fortunately, Abbie is an excellent sport and fully supportive of my diet plans. Thus, I will actually be flying all of my groceries to Lake Tahoe with me (thank goodness Southwest allows a free checked bag). I am sure at some point that I will end up straying from the meal plan, but I will still aim to eat MyPlate meals and meet my calorie goals each day. After all, adaptability is an essential life skill, is it not?