Carbohydrates are the body's preferred energy source. They are abundant in most food of plant origin, and when consumed in as close to their natural state as possible, offer a myriad of health benefits. Why then have “carbs” become so popularly maligned?  They seem to have usurped saturated fat as the perennial bad guy in the battle of the bulge. The reality is that when the right kinds of carbohydrates are consumed in the right quantities they pose no threat to the waistline. The key point to understand in this matter is that all “carbs” are not created equal. 

All living organisms are based on carbon in varying forms. Carbohydrates are formed when carbon is linked with oxygen and hydrogen either in single molecules or in some cases hundreds of molecules. This determines whether they are considered “complex” or “simple”. Simple carbohydrates consist of just one molecule- sugar- and are termed “monosaccharides”. Complex carbohydrates, or “polysaccarides” are longer chains of sugar molecules, and as a consequence, take longer to get broken down by the body. 

Because complex carbohydrates take longer to break down, the molecules of sugar enter the blood stream slowly. The benefit of this is that blood sugar levels remain stable throughout the day, resulting in consistent, long lasting energy without peaks and valleys. Simple carbohydrates, on the other hand, enter the blood stream quickly, resulting in a sudden spike in blood sugar. To combat this sudden rise in sugar the body  secretes a massive amount of insulin. Insulin is an anabolic hormone that drives nutrients into the body's cells, and thus promotes fat storage. Repeated insulin spikes can promote insulin resistance, or a desensitizing  to the hormone, which in the long run can cause diabetes.   

Carbohydrates are stored in the muscle cells and the liver as glycogen. The body has a limited capacity to store glycogen and any excess is converted to body fat. Over consumption of carbohydrates, particularly of the refined, simple variety, are a leading cause of weight gain in the United States. Sugar consumption has increased 28% since 1983, and obesity rates have correspondingly sky-rocketed. To a large degree this increase in sugar consumption is due to increased consumption of soft drinks. It is estimated that the average person in the United States today drinks an average of 1.6 12 ounce cans of soft drink everyday. Each soft drink contains an average of 10 teaspoons of sugar. This contributes heavily to the estimated 170 pounds of sugar consumed by the average American annually.  

Not only does over consumption of refined sugars lead to weight gain and potentially diabetes, they have the potential to rob the individual of essential nutrients. Simple carbohydrates can be refined to the point where all vitamin and mineral content is lost, providing very little nutritional benefit. This gives us the term “empty calorie”. 

Aside from soft drinks, refined carbohydrates to avoid can be found in products made from white flour, such as white bread, white rice, pancakes, muffins,and bagels. Less refined alternatives are whole grain bread, brown rice, oatmeal and wholewheat pasta. Unrefined carbohydrates retain the outer husk of the grain, which is where much of the vitamin content is located. Whole grains also contain fiber, which promotes digestive health and a feeling of fullness, which generally results in a lower caloric consumption and therefore aids weight loss.  

In health and fitness circles there is a popular theory that one should avoid carbohydrates at night. Whilst there is some merit in this line of reasoning, when it comes to weight loss, this theory focuses unnecessarily on the finer details. The main focus in weight loss should be over all energy intake, of which complex carbohydrates should be the chief component. Carbohydrates are metabolized the same regardless of what time of day they are consumed, and if there is too much, the excess will be stored as fat. However, a high carbohydrate intake late at night may adversely affect growth hormone levels, which ideally should be at their highest during sleep. A small to moderate amount of complex carbohydrates at least 2 hours before bedtime will not harm growth hormone levels to any significant degree and may in fact help elevate serotonin levels in the brain, a neurotransmitter associated with feelings of tranquility, and can thus aid restful sleep. 

Is it ever acceptable to eat simple carbohydrates? Yes, as fruits contain the monosacchride fructose. Fruits are generally very low in calories and high in fiber, so in this case the simple carbohydrates they contain are unlikely to promote fat storage. I am yet to meet anyone who became obese form eating too much fruit. Fruits contain essential vitamins, especially vitamin C which is abundant in citrus fruit. 

In some situations the body actually needs quickly digested carbohydrates. This is in situations where muscle glycogen stores have been heavily depleted, such as which occurs after strenuous exercise. Simple carbohydrates like those found in bananas or even straight glucose is ideal for rapidly restoring glycogen levels and promoting recovery. How much to consume will depend on the intensity and duration of the physical activity. Two hours of endurance type activity will require 100 to 200 grams of carbohydrate within two hours of the cessation of the activity. However, for a hard training athlete such as this, it is the overall quantity and quality of carbohydrate intake that will have the most profound effect on recovery. For the vast majority of us, our post exercise needs will fall well short of such amounts. However, the body is most efficient at carbohydrate uptake in this post exercise period, so it makes sense to consume our biggest carbohydrate meal (and hence most calorie dense meal) during this metabolic window of opportunity. 

Zero and low carb diets are impractical and difficult to maintain. For a healthy and long term approach to weight management, carbohydrates should form approximately 55% of total calorie consumption, the bulk of which should be comprised of vegetables, fruit, and whole grains.