Extreme diets suck. For most people most of the time, it is best to balance the food that you need according to pyramid charts for your gender and age, and according to your body metabolism and exercise routine. Low carbohydrate may work for a few weeks at a time, but they are not a good idea if you exercise at an intermediate or higher level regularly, and especially if you also have an intense lifestyle of mental and physical work.
Your brain and muscles use primarily glucose for energy. At rest, the Brain uses about 20% of the blood glucose, and muscles use about 30% of blood glucose. During exercise, muscles may use up to 30 times this amount. The body has a limited capacity to store carbohydrates. When the capacity is met, glucose is metabolized to fat to be stored. This fat cannot be converted back to glycogen. It must be burned. So eating too many carbohydrates can make one fat.
Alternatively, if there is not enough carbohydrate intake, athletic performance will not be good, and the athlete may crash. Without glucose, the liver cannot metabolize fat for energy. The athlete will hit the wall. This is why marathon runners often eat carbohydrate gels like Power Gel along their ride. If the brain does to have glucose during exercise, athletes will feel lightheaded and weak.
The average American diet provides about 1.8 grams to 2.3 grams of carbohydrate per pound of body weight. For optimal glycogen storage, a carbohydrate intake of 3.2 to 4.5 grams per pound of body weight is needed. People who train lightly for less than 1 hour a day need 2.3 to 3.2 grams of carbohydrate per pound of body weight. This optimizes glycogen storage for most athletes training for 1 to 3 hours a day. Athletes training 4 or more hours a day need 5.4 to 5.9 grams of carbohydrate per pound of body weight.
Some of this information was taken from Winning Sports Nutrition by Linda Houtkooper, PhD, RD, FACSM, Jaclyn Maurer Abbot, PhD, RD and Veronica Mullins, MS, RD, CSCS.
Disclaimer: None of the above information can be taken as a substitute for advice from a medical professional such as a physician.
My third book, Pocket Guide to Fitness, is available on www.louizapatsis.com, http://www.authorhouse.com, www.bn.com and http://www.amazon.com. If you look up my name on those Web sites, you will find my other books The Boy in a Wheelchair and Life, Work and Play: Poems and Short Stories.