Low carbohydrate diets have gained a lot of publicity recently, thanks to folks like Dr. Atkins, Dr. Schwarzbein, Dr. Bernstein, and a host of others. Despite the credentials of these folks, there is still an acrimonious debate on the merits of low-carb diets. Ok, what are ‘carbs’? And what’s the Big Deal?
Let’s start with some basic chemistry. (If you are chemistry-averse, you can skip the rest of this paragraph.) A carbohydrate a molecule made up of carbon, oxygen, and hydrogen with a general ratio given by the formula Cm(H2O)n (where m could be different from n, and there are some exceptions to the hydrogen to oxygen ratio of 2 to 1). Carbohydrates include a range of molecules from simple sugars such as glucose to complex long-chain molecules such as cellulose (or fiber).
Simple carbohydrates can be used almost directly by the body for energy. The basic building block of carbohydrates is the saccharide. Glucose is a monosaccharide (one saccharide), table sugar is composed of the disaccharide (two saccharides) fructose combined with glucose, and cellulose is a polysaccharide (many saccharides). In the middle of that range is starch, which the body can easily break down into sugar.
Fruits typically contain fructose, and dairy typically contains lactose (both disaccharides). Both of these sugars can cause problems for people who are sensitive to them. Foods such as pasta and bread, which contain processed wheat, contain large amounts of several different carbohydrates, varying from relatively benign starches to unusual types of carbohydrate such as amylopectin-A. The carbohydrates in processed foods can be absorbed very rapidly by the body. In particular, amylopectin-A can raise blood sugar even faster than table sugar.
Complex carbohydrates take longer to digest, and some carbohydrates such as cellulose (fiber) are not digestible at all, but serve to slow down the digestion process of other foods. These complex carbs are found in green leafy vegetables, legumes, and other unprocessed plant foods. For instance, oatmeal, which has more fiber than most processed grains, will fill you up for longer than sugary cereal due to the way the body uses and processes the carbohydrates.
Carbohydrates are first processed by the saliva in the mouth, which contains enzymes which can break down starches (up to a point) into sugars. These sugars are transported directly to the liver, which converts some of the sugars into glucose and releases them into the bloodstream, and converts any excess to triglycerides. The pancreas detects the presence of glucose, and in response, produces insulin. One of the functions of insulin is to facilitate transport of glucose into the cells, where the mitochondria can break them down for energy.
The higher and faster the blood sugar increases, the more insulin is produced. If the glucose level goes abnormally high, the insulin production will “overshoot” and cause the blood sugar to go very low. This is the “blood sugar roller coaster” effect, which causes you to be hungry and lethargic an hour or so after eating a meal containing a lot of simple carbohydrates. Complex carbohydrates take longer to digest, so the rise of blood sugar is slower, which gives the pancreas more time to fine-tune the insulin response.
If the pancreas is stimulated into producing large quantities of insulin over a long period of time, it can “burn out,” leading to the disease called type II diabetes.
Glucose which is not immediately needed for energy is stored in the liver and the muscle cells as glycogen, which serves as a small reservoir of readily-available energy. The capacity to store glycogen is very limited, and once that capacity is full, excess glucose is converted to triglycerides, which is then stored away as fat. The body’s capacity for fat storage is orders of magnitude greater than for glycogen storage. Another of the functions of insulin is to facilitate fat storage, so as long as excess carbohydrate is present, the body will not use the energy in the fat storage.
The optimal amount of carbohydrate in the diet depends on your activity level, and in some cases, may depend on how much damage has been done to your body by chronic high levels of glucose in your blood. Many of the suggested levels of carbohydrate consumption (such as from the World Health Organization) are really only appropriate for athletes (and there is some controversy about the need for carbohydrates by athletes).
One of the myths prevalent in the medical establishment (and among proponents of low-fat diets) is that the body must have some carbohydrate in the diet in order to function properly. The fact is that the liver can convert protein into glucose in a process called gluconeogenesis. There are only a few organs in the body which must have glucose for a fuel, and the liver is capable of making more than enough to fill those needs.
Another myth is that insufficient carbs result in problems such as fatigue, poor mental capacity and muscle cramps. This is actually true in the short term, if your body is not fat-adapted. The fat adaptation process may take a week or more, after which fatigue and brain fog go away. This process of adaptation has been labeled “Atkins Flu,” and can usually be avoided by gradually reducing dietary carbohydrates instead of suddenly and drastically cutting them out.
Extremely low carbohydrate diets can (but don’t necessarily) result in some problems in the long term. These problems can include dry-eye or digestive problems, which can become just as serious as the problems caused by too much carbohydrate. Including a relatively small amount of complex carbohydrates (typically less than 150g/day, although for some people, 30g/day or even less will do the trick) in the diet will usually solve or prevent such problems. Individual carbohydrate tolerance is highly variable.
Most of the fuss over low-carbohydrate diets is a result of the fact that the dominant recommendation of the medical community has been low-fat, which is a result of the fact that a prominent proponent of low-fat diet managed to get into a position of considerable political power in the late 1960’s.
Low-carb diets have been shown in several clinical studies to be much more satisfying and effective for weight loss, much to the consternation of low-fat advocates. Low-carb diets have also been shown to no less healthy than low-fat diets (and much healthier than the extreme low-fat diets recommended by “diet gurus” Dr. Dean Ornish and Dr. John McDougall).
- Atkins for Life: The Complete Controlled Carb Program for Permanent Weight Loss and Good Health
- The Schwarzbein Principle: The Truth about Losing Weight, Being Healthy and Feeling Younger
- Dr. Bernstein’s Diabetes Solution: The Complete Guide to Achieving Normal Blood Sugars
- Protein Power: The High-Protein/Low-Carbohydrate Way to Lose Weight, Feel Fit, and Boost Your Health–in Just Weeks!
There are lots more, but these should give you a really good start on a healthy low-carb diet plan.