Outside magazine, February 1996
Professional triathlete Wendy Ingraham had a day of dietary reckoning a couple of years back as she tried to slip into her ski outfit on a vacation: "My pants weren't coming on too easily, and the harder I pulled, the tighter they felt. I'm thinking, 'How can this be happening to the skinny woman who finished fifth in the Ironman just a few months ago?'" As it turns out, her oatmeal breakfasts may have had something to do with it. Ditto the brown rice and the bagels. Many top-ten triathlon finishes later, the svelte, five-foot-nine Ingraham now suspects that carbohydrates betrayed her. An endurance jock burned by carbo-loading? It sounds as counterintuitive as eucalyptus leaves turning on a koala. But according to a small yet convinced group of researchers and athletes--and contrary to what a wide body of data has established--overdoing carbohydrates causes a hormonal reaction that increases our stored fat, impedes our ability to burn that fat, and restricts the flow of oxygen to our muscles, building love handles and curtailing athletic performance.
This concept alone is enough to rile many a sports nutritionist, but what's really making them squirm is the prescriptive: a diet in which the percentage of calories from carbohydrates barely exceeds those obtained from protein or fat, as opposed to the old standby in which carbos serve up roughly 60 percent of the calories. The 40-30-30 approach--meaning that from every meal, an athlete should get 40 percent of the calories from carbohydrates, 30 percent from protein, and 30 percent from fat--is based on the premise that a more even distribution of the three dietary components means more even hormone levels to sustain steady endurance efforts. Six-time Hawaii Ironman winner Mark Allen and 1995 Triathlete of the Year Mike Pigg, as well as the NCAA-champion Stanford men's and women's swim teams, are the new diet's poster children. But how do we know when to put away the pasta bowl?
"People need to start thinking of food from a hormonal perspective," says Barry Sears, a biological chemist and president of Surfectant Technologies in Marblehead, Massachusetts, who has worked on hormone control for cardiovascular-disease patients and elite athletes alike. The key figure in the crusade against carbo-loading explains, "Once you look at it that way, you can understand that dietary fat alone isn't so disruptive. But the hormone insulin can be, and one of the quickest ways to trigger an increase of it is by eating too many carbohydrates. For endurance athletes interested in keeping the flow of fuel constant, virtually all of the dietary recommendations being made are wrong."
The basic pro-carbo argument, which Sears condemns, is that an exercising body's most accessible and burnable fuel is muscle glycogen, a stored form of glucose. And since the best source of glucose is carbohydrates, the long-accepted wisdom says you should stock up. "I wouldn't think twice about recommending that an athlete's [caloric intake] be 60 percent carbohydrates, 25 percent fat, and 15 percent protein," says Ellen Coleman, a sports nutritionist and exercise physiologist in Riverside, California, who's worked with Dave Scott, the other six-time Hawaii Ironman winner. "Glycogen is still the fuel of choice."
Beget Good Eicosanoids
Another argument against carbo-loading is that since insulin is known to prevent fat from being mobilized, and since, as Sears claims, most people who fill up on carbohydrates will secrete a high amount of insulin, athletes might have a hard time accessing their calorically rich fat stores. And that can be a problem when glycogen supplies start to dwindle some 45 to 90 minutes into a workout. To top it all off, insulin does such a fine job of ushering glucose out of your bloodstream that you can feel hungry before you've done the dishes from your carbohydrate-rich lunch. "The craving that comes 90 minutes after a huge pasta meal means that the insulin has carried the glucose away and that it's preventing your body from getting at the glycogen that's stored in your liver," Sears explains. "Your sugar-starved brain is telling you to turn to external resources for more. You're entering carbohydrate hell--you're a slave to Oreos."
As adamant as Sears is about lowering insulin, he's convinced that building up good eicosanoids is the key to avoiding dietary damnation. Eicosanoids are what Sears calls superhormones, meaning they control other hormones such as insulin. There are both good and bad eicosanoids: The good ones will decrease insulin levels and increase blood flow, thus increasing the amount of oxygen that gets to working muscles. Bad eicosanoids will do just the opposite. In the end, either type of eicosanoid begets more if its kind, and Sears says eating meals that are relatively balanced in carbohydrates, protein, and fat generates good eicosanoids.
All of which nutritionist Coleman considers poppycock. Her objections, with a 15-year body of research behind them, range from the fact that the insulin reaction to sugar can vary widely from person to person to the thin amount of scientific evidence showing the performance benefits of a relatively low-carbo diet.
Pick Your Proteins, Package Your Carbos
According to Sears, the starting point for the 40-30-30 diet is protein. Protein is the main building-block of our cells and stimulates the production of the hormone glucagon, which works as a foil to insulin: It releases glycogen from the liver, which in turn stabilizes the amount of glucose in the blood. Sears claims that when protein is eaten alongside and in near equal proportion to carbos, a steadier level of blood sugar is maintained, keeping you out of the tumultuous cycle. "A good rule of thumb is that whatever size serving of low-fat protein you eat be accompanied by twice the quantity of a high-fiber carbohydrate source--something like steamed vegetables," says Sears. His superior protein suggestions include chicken, fish, low-fat cottage cheese, egg whites, and soy products. Good carbohydrates--sorry, linguine loyalists--include green vegetables such as artichoke, broccoli, and spinach and some fruits such as cantaloupe, strawberries, and grapefruit. As for pasta and bread, they're way down on the list because of the speed at which they put glucose into your bloodstream (see "The Absorption Race").
Fat in the 40-30-30 diet is there to provide the body with essential fatty acids, added energy stores for when your body runs low on glycogen, and any necessary calories that the carbo-protein combo doesn't provide. Of course, unsaturated fats (vegetable oils, nuts, nut butters, avocados) prevail over butter, cream cheese, and bacon. Cautions Maffetone, "Keep in mind that all of those reduced-fat and no-fat desserts have a lot of carbohydrates, which you'll end up storing as fat anyway."
Such a metabolic switcheroo has Wendy Ingraham carefully watching her carbohydrate consumption the way the rest of us keep cookies in check. Her pretraining meal is now a fried egg on a bagel for carbohydrates, protein, and fat in near equilibrium. "Meanwhile, my boyfriend--he's a pro mountain biker--will eat three huge slices of bread before heading out the door, and then he'll want to stop for a muffin 20 minutes later," she says. "When I see that, I know I must be doing something right."
Andrew Tilin, a former senior editor of Outside, completed last year's Leadville 100 mountain-bike race on a suspiciously high-carbohydrate diet.