One interesting fact about the issue of gaining and losing weight is perhaps the acknowledgement that although portion size does matter, the macronutrient composition of a meal does however play more significant roles. As a consequence, there are quite a lot of weight loss diets which have made macronutrient manipulation their focus.
One such macronutrient manipulation concept is that of carbohydrates and their use in low-carbohydrate diets which have over the years been vilified to varying degrees but have also been seriously misunderstood by a generality of weight loss seekers.
But why all the fuss about carbohydrates? What roles do they play in the body and how do they and these low-carbohydrate diets impact on weight loss for experts to have been involved in so much divergent arguments about them?
Carbohydrates are almost exclusively from plants, vegetables, and grains with the exception of milk which is the only animal-based product which has a significant amount of carbohydrate. Essentially, there are two types of carbohydrates namely: simple carbohydrates (which due to their smaller particle sizes are more easily broken down by the body and therefore provide the fastest source of energy for the body) and complex carbohydrates (mostly starch and fiber).
The human body requires carbohydrate more than any other macronutrient because it is the fastest burning energy of the three (with fats and proteins being the other alternatives) and it is what the muscle cells and the brain in particular, are designed to almost exclusively run on.
While all carbohydrate-containing foods are generally metabolized to produce glucose, the body however does not immediately make use of all the produced glucose that is released into the bloodstream. The liver and muscle cells convert about one-third and two-third respectively into a storage form known as glycogen while any excess is stored as fat in adipose tissues.
Although glucose is the body's primary source of energy most especially for the brain, muscles however only use glucose for short-term bouts of activity. Glycogen on the other hand, serves as the body's auxiliary energy source and is only released and converted back into glucose through the process of glycolysis whenever blood glucose levels become too low or during any possible "fight or flight" situation.
However, when there is excess amount of glucose in the bloodstream, specialized cells in the pancreas secrete insulin (a hormone responsible for facilitating the storage of glucose as fat in fat cells) to normalize blood glucose levels. The over-secretion of insulin due to the excess amount of glucose in the bloodstream is what generally leads to body weight gain. And this is where the effect of excess carbohydrate consumption actually rears its ugly head.
Low-carbohydrates diets, such as the Atkins Diet and the South Beach Diet, are based on the premise that it is not fat that makes people fat but carbohydrates. These diets are therefore of the view that carbohydrates (especially simple carbohydrates) are so quickly metabolized and absorbed into the bloodstream that they make dieters get hungry too quickly after meals and thus tend to overeat.
However, this view of promoters of low-carb diets especially the Atkins Diet generated a lot of disparagement as a lot of nutritionists and dietitians were of the opinion that diets should rather be low in fat and high in carbohydrates, combined with plenty of grains, fruits, and vegetables and dieters should limit their intake of meat and other dairy products. Although the opinion of the experts became the de facto for dieting in the 1980s, the obesity epidemic however started escalating with the generality of western cultures including the American populace, starting to put on extra weight.
Low-carb diets however regained popularity when people found it difficult to lose weight and keep it off using low-fat high-carbohydrate diets. This renewed interest in the use of low-carb diets was partly as a result of several small-scale studies which began suggesting that low-carbohydrate diets may actually be more effective in helping people lose weight. Several of these studies demonstrated that the use of low-carbohydrate diets may not actually have all the harmful effects earlier associated with them by critics.
A recent study conducted in 2003 by researchers at the University Of Pennsylvania School Of Medicine found that using a low-carbohydrate diet resulted in a more significant weight loss when compared to a conventional low-calorie, low-fat diet during a six-month period. Other studies are also of the opinion that although most benefits were short-term, the negative effects will take decades to become evident.
Low-carb diets generally result in rapid weight loss during the initial phases because most of the weight loss actually comes from the loss of water from body cells. This water loss is due to the fact that reduced carbohydrate intake generally forces the body to deplete its blood glucose forcing muscle tissues to convert their glycogen store back into glucose and release them into the bloodstream. The depletion of muscle glycogen results in a significant water loss as glycogen is composed of about 75% water and 25% glucose.
Besides the effect of glycogen depletion, a high-protein/low-carb diet can also increase body water loss due to the fact that the kidneys would require a lot more water from body cells to be able to flush out the elevated nitrogenous compounds produced by the metabolism of protein which produces carbon dioxide, water, ATP (the basic unit of energy), urea, and ammonia.
However, the actual weight loss effect of a low-carb diet is mostly as a result of two other physiological effects. First, a low-carb diet causes a reduction in the production level of insulin which helps to reduce storage of glucose as fat in the body. And secondly, low-carb diets generally force the body to go into a state of ketosis - whereby the body is practically forced to start burning its fat deposits to produce energy.
Conclusively, other than the issue of non-sustainability, no major study or research has been able to categorically prove that low-carbohydrate diets are harmful to a person's health despite their non-relenting criticisms.
Nonetheless, while it is important to note that there are some possible side effects such as the reduced energy levels experienced by most people during the first phase of most low-carb diets, the overall idea of it reducing insulin production is fundamentally sound.
Therefore, the best advice that can be inferred about using a low-carbohydrate diet for optimal weight loss results, is that there is the need to significantly reduce (without necessarily extremely reducing) the consumption of high glycemic index and high-density carbohydrate foods in every meal. Balance and portion size control should therefore become the watchword.