By now weall know that many athletes, depending on their sport, need carbohydrates tomaximize their performance. In fact, hundreds of studies conducted over thepast several decades have shown that carbohydrates help athletes fill up theirfuel tank and keep them going over the long haul. Low fuel, in the form ofglycogen, leads to poor performance. So why are so many personal trainers tellingtheir clients to go on lower carbohydrate diets? And do low-carbohydrate dietswork?

Carbohydrate and Athletic Performance
Beforelooking at low-carbohydrate diets and the type of carbohydrates people eat, itis important to understand what carbohydrates do for athletic performance. Moderateto high-intensity exercise relies on muscle glycogen for energy. Therefore,athletes need to consume carbohydrates before going out on a long ride or runor play in a tournament for hours on end. Doing so will help them top off theirglycogen fuel tank so they can exercise for a longer period of time beforecrashing. This pre-training, game or race meal should consist of a good amountof low fiber carbohydrates and some protein for staying power (fiber slowsdigestion and no athlete needs an emergency bathroom visit in the middle of arace). But because our glycogen stores run out in two to three hours max (orsooner if we are exercising intensely), athletes also need to consumecarbohydrates during exercise. Not just any carbohydrate will do.

Research has found that consuming multiple types of carbohydrate duringexercise (termed "multiple transportable carbohydrates") is the bestapproach for fueling. Each type of sugar has its own transport mechanism. Whenwe combine more than one type of sugar, we replenish our blood glucose moreefficiently without overwhelming, or maxing out, one transport mechanism.Therefore, your hardcore endurance clients should opt for sports nutritionproducts that contain more than one type of sugar -- glucose, fructose andgalactose, for instance -- compared to a sucrose-only beverage.

In additionto pre-activity carbohydrate fueling and during-exercise carbohydrate fueling,athletes also need carbohydrates after long bouts of activity to refill theirglycogen stores. How much? Post-training carbohydrate needs depend on theduration and intensity of the workout.

Why Low Carb?
Despite all the research and recommendations for carbohydrates, why are so manypeople advocating that we cut down our carbohydrate intake? For one thing, therecommendations on carbohydrate fueling are for athletes -- people who workoutintensely most days of the week. Weekend warriors or gym goers who hit theelliptical machine four times per week do not need to load up on carbohydrateimmediately after exercise. Likewise, if a client works out for less than onehour, they don't need a sports drink (unless they are trying to gain weight andneed the calories). In fact, your clients can workout for even longer than anhour without carbs (though they need water and may need electrolytes) dependingon the type of workout they are doing and their goal. And, if they aren'texercising again within 24 hours, they have plenty of time to restore glycogenthrough their meals (making that post-exercise carbohydrate recommendation lessimportant).

In additionto the fact that the average gym goer does not need to push carbohydrate like ahardcore ultra runner does, Americans in general have abused carbohydrates foryears. According to the U.S. Department of Agriculture, the average Americanconsumed 430 calories a day from grains in 1970. Fast forward through the fat-free90s, and by 2008 we were chowing down on 625 calories from grains every day. Notwhole grains either. A whopping 90% of the grains we consume are refined --sugar, white bread products and white rice, for example.

We didn't dothis in isolation. Our carbohydrate heyday got a helping hand from restaurants,which happily served customers unlimited cheap grain products (think tortillasand bread) before the main course even hit the table. More food, less money = ahappy customer. Then, this main course would sometimes double, triple orquadruple the recommended grain serving size by supersizing and pairing onecarbohydrate with another carbohydrate (fajitas on flour tortillas with a sideof rice). Restaurants aren't the only group that jumped on the bandwagon. Foodmanufacturers, in an effort to appease their customers, created fat-freeeverything.

Arecarbohydrates bad? Absolutely not. But the amount of carbohydrate we consumeand type of carbohydrate we consume is an issue, for some people. A good amountof research shows that lower carbohydrate diets can be effective, especially inthe short term, for obese individuals who want to lose weight (especially ifthey have insulin resistance, PCOS or type 2 diabetes). However, this is wherescience and anecdotal experience collide head on. People live in the realworld, not a university lab setting with all meals cooked and prepared forthem. And though some hardcore meat eaters can happily cut their carbs, shedweight and call it a day, for others, cutting carbs too low can take thepleasure out of eating and lead to a sense of failure the moment a piece ofbread passes their lips. In instances like this, the quest for weight lossinvolves a mix of behavior, psychology and food that all need some work. Inprofessions where we aim to help people improve their lives, possibly the worstthing we can do is set them up for feelings of failure and disappointment whenthey can't stick with a strict diet regimen.

In addition to the need for a very delicate approach in regard to body size,weight and diet by both personal trainers and dietitians, dietitians are alsodigging deeper into very specific details of one's diet, medical history andhow they feel. Food sensitivities and intolerances are an area where specifictypes of carbohydrates may need to be weeded out of the diet. As noted by JulieBurns, MS,RD, CCN of Sportfuel Inc. and Eat Like the Pros LLC, gluten is gaining more andmore attention:

The sticky,little hard to digest protein, found in wheat, rye and barley products andhidden in sauces, creams and other packaged goods, causes many problems in ourclients. When we test for nutritional status and gluten sensitivity, we oftenfind multiple nutritional deficiencies along with gluten sensitivity. If theperson adopts a gluten free diet and corrects nutritional deficiencies, theysimply get better! While the diet may be challenging, it can be an extremelyworthwhile and a life changing journey. Several of our professional athleteswho have adopted a gluten free lifestyle have experienced better energy,improved body composition, reduced soreness, and so much more. That said, wefocus on teaching our clients to eat real food--as nature intended- to promotehealth and performance, and not to overemphasize gluten free processed foodssuch as excessive gluten free breads, pastas and sweets. These real foods areeasy to digest and help to provide abundant antioxidants, vitamins and mineralsthat gluten-free processed foods.

So what'sthe bottom line on carbohydrates? Athletes, depending on their sport, need topay acute attention to the types and total amount of carbohydrate they areconsuming. The average American adult gym goer should not be following thecarbohydrate recommendations set forth for athletes. It's time for people tostart paying closer attention to both portion sizes and the type ofcarbohydrates they are consuming.

Marie Spano,MS, RD, CSCS, CSSD is one of the country's leadingsports nutritionists. She combines science with practical experience to helpOlympic, professional, and recreational athletes implement customizednutritional plans to maximize athletic performance. Spano is the sportsnutrition consultant at Competitive Edge Sports and runs Spano Sports NutritionConsulting.

AicaciaYoung is President-Elect of the Student Dietetic Association at Louisiana StateUniversity and currently interning at the University of Kentucky.