The Role and Basic Application of Dietary Carbohydrate for Body Composition

From a nutritional standpoint relating to body composition, carbohydrates are often misunderstood, neglected or vilified as being the cause for a variety of health problems such as obesity. This write up is meant to clear up the misunderstanding and identify what carbohydrates are, what they do, and how to use them for optimal body composition.

Carbohydrates are the main energy fuel for activity and brain function.They are categorized as simple or complex. Simple carbs are essentially sugar. This could be further defined, but for the purpose of this post and basic understanding, it isn’t necessary. Complex carbs are most plant based starches, including fruits, vegetables, cereals and grains, which also will typically contain dietary fiber. These are generally digested more slowly due to their complexity and fiber content, which will in turn provide energy over a longer period of time. Carbohydrate is stored as glycogen in skeletal muscle and the liver, whereas the amount of available glycogen you store is directly related to the amount of carbohydrate you consume. The more stored glycogen available, the longer and harder an athlete (or anyone dependent on fitness level) is able to work, achieving better results. This doesn’t necessarily mean though, that more is better. Too much will either; create an unwanted net caloric surplus, or not leave enough room for the desired amount of dietary protein and fat while still remaining within the individually determined caloric range.

Being that carbohydrate is the preferred fuel for activity, weightlifters as well as runners, CrossFitters, bodybuilders and even the generalist all need carbohydrate to improve their performance and body composition. If lean muscle is preferable to fat in terms of body composition and overall health, carbohydrate is an essential nutrient to drive the construction and maintenance of lean muscle and aid the body in resisting fat gain. The question is: What and how much?

High Glycemic vs. Low Glycemic Index

Complex carbohydrates are generally considered to be optimal for a healthy diet and should be taken in at every meal. Some types of carbohydrates affect the glycemic response quicker than others, elevating blood glucose and insulin more quickly and therefore affecting the energy output. The glycemic index is scored out of 100 against straight glucose. In general, a score of 55 or less is considered low. 56-69; medium. And, over 70, high (GI). Some consideration should be placed on the type of carbs, and how they affect the insulin response. Usually, low GI carbs should be emphasized for pretty much any meal with the exception of the timing of exercise/ training activity. According to the International Society of Sports Nutrition, the ingestion of high glycemic carbohydrate may have benefit immediately following intense exercise in replenishing muscle glycogen and enhancing recovery from workouts. But the farther away from exercise, training or competition, the lower GI carbs should be consumed. Below is a list with examples of both high GI and low GI carbohydrate sources, ranked from lowest to highest.

Starches, Cereals, Grains, and Legumes                                             Fruits

Chickpeas               28                                                                        Cherries           22

Kidney Beans          28                                                                        Grapefruit        25

Lentils                     29                                                                         Apricot (dried) 31

Pasta                      35-40                                                                    Apples/ Pears  38

Bulgar                    48                                                                          Plum                39

“Grainy” Breads     49                                                                          Peach              42

Brown Rice            50                                                                         Grapes              46

Buckwheat             54                                                                          Orange            48

Basmati Rice         58                                                                          Banana            51

Quinoa                   53                                                                         Pineapple         59

Oatmeal                 55                                                                         Cantaloupe      65

Potato (New)         57                                                                          Watermelon     72

Corn                      60

Sweet potato         61

Potato (baked)      85

It is important to know that any type of workout or exercise will deplete muscle glycogen stores. Many people are used to having a protein shake post-workout, but, it would be better to combine that protein shake with carbohydrate. In this case, a high glycemic carbohydrate source may be optimal to help replenish glycogen stores and facilitate the recovery and repair process by returning the body back to a positive protein balance.

How Much Carbohydrate Do You Need?

General recommendations for an active individual are between 55-65% of your total, daily caloric intake. Or, between 5 to 10 grams per kg of body weight, dependent on the type of exercise or training. The lower end of the spectrum would be more strength based training, the higher end; more endurance/ circuit training, though higher carbohydrate can help with the strength training as well. Too often, carbohydrates are blamed for health issues such as obesity and disease when in actuality, carbohydrates are essential to the improvement and maintenance of lean body mass through exercise and training and have a direct effect on performance. On the flip-side, most carbohydrates are easily over-consumed which is why it is crucial to understand food preparation, cooking, portioning, and overall intake to meet fitness, health and body composition goals. Neglecting or avoiding carbs for fad diets will only hinder your ability see optimal results from exercise/ training, and likely create an unfavorable amount of dietary fat intake to make up for the carbohydrate deficit.

It is important to understand that carbohydrates are not “bad”. But eliminating or avoiding them almost entirely will make it very hard to maintain lean muscle due to the extreme caloric deficit that accompanies that elimination. Low GI Carbohydrate and protein that is taken in at every meal based off of the needs of the individual should be the focus in order to maintain adequate energy and positive protein balance. Once that is in control, carbohydrate numbers can be modified a bit to create a net caloric deficit which will allow for a slower (but sustainable and healthy) loss of body fat.

For more information:

Other sources:

Krause’s Food, Nutrition, & Diet Therapy

High Performance Nutrition By, Susan M. Kleiner, PhD, RD

Sports Nutrition & Performance Enhancing Supplements By; Abbie E. Smith-Ryan, PhD, CSCS*D, CISSN and Jose Antonio, PhD, FNSCA, FISSN, CSCS


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