His goal: rather unusual. His question: pretty typical.

A younger cycling teammate has decided to enter a five-day stage race this May and will compete in the toughest category. This stage race follows the same concept as the Tour de France, but is only a quarter of the days and a tenth of the distance.Yet it really couldn't be any longer than that. Really. For the course is not only exceptionally hilly but also rocky, rutted, and ridiculously narrow at spots.In other words, my teammate is doing a five-day stage race off-paved roads and up Pennsylvania hills on a mountain bike.He's already a skinny guy but wants to be ultra-light to excel on the climbs. So on a recent ride, he asked me something I've probably been asked a hundred times: "Should I go on a low-fat or a low-carb diet?"Although a fast-paced ride with three other excellent cyclists is not the best time to answer such a question especially when the real feel is 18 degrees at the start and you're the underdressed old guy I did my best to provide an answer.In hindsight, there's some stuff I left out as well as a pithy reply that I can't believe I didn't employ. For when a serious athlete of any sort even someone who doesn't compete but still likes to push hard during workouts asks me, "Low-far or low-carb?" I should say, "Neither," wryly smile, and then add, "both."This evasive and seemingly contradictory response is based on a few factors. First, a low-carb diet generally is best for weight loss; second, carbohydrates are definitely the preferred fuel source for moderate to intense physical activity; third, too many so-called low-fat diets aren't low enough in fat to really be effective; fourth, success with a low fat diet only occurs if protein ingestion remains high and the carbohydrates consumed are complex rather than simple.A 2014 study published in the Annals of Internal Medicine comparing low-fat and low-carb diets found what many past studies have found: that more weight loss occurs, especially initially, with a low-carb diet. In this study, 148 obese volunteers were assigned one diet or the other, and in one year those on the low-carb diet lost an average of nearly 8 pounds more than those following a low-fat regiment.Moreover, most their blood workup results were better, meaning they registered lower triglyceride and higher HDL cholesterol readings yet remained on par with the low-fat group in overall cholesterol.These results are especially significant because they contradict the old notion that a low-carb diet (aka a high-fat diet) will adversely affect heart health long term.But something else is significant about this study: the protocol. What the researchers were calling low-fat and low-carb diets didn't seem accurate or fair.Those assigned the low-carb diet limited carbohydrate ingestion to less than 40 grams of carbs a day, which caused an overall 75-percent decrease in carbs.Those placed in the low-fat group, however, only reduced fat ingestion to 30 percent even though their average before the study began was 35 percent. The low-fat group was also instructed to eat no more than 55 percent of their calories from carbohydrates.This is not my idea of a low-fat diet.In fact, hardcore low-fat diets keep fat ingestion to between 10 and 15 percent fat and make certain that the carbohydrates replacing the eliminated fats are a certain type: healthy, blood-sugar-stabilizing, high-fiber-containing complex carbohydrates.So I see the Annals of Internal Medicine study as an unfair fight. Proof of that is that both the low-carb and low-fat groups ingested the same amount of fiber throughout the study. People following a true low-fat diet consume far more fiber than those on a low-carb regiment.But you can learn from this study, and my cycling teammate can incorporate the info into his get-ultra-lean eating plan. When he's riding hard, he should follow the hardcore goal of a true low-fat plan to eat no more than 10 to 15 percent of his daily calories in the form of fat yo-yoing the percentages of protein and complex carbohydrates he consumes based on the ride's length and intensity.On days he isn't pushing his body to the limit, days where he does a recovery ride or a long, base-miles ride, he should consume a higher percentage of protein and a lower percentage of carbohydrates, in essence, eat a low-carb diet. Preferably, he would do these rides early in the day on an empty stomach, a strategy that causes the body to burn more stored fat than normal for exercise energy.And on those days when he rides long and hard, he needs some complex carbs three hours before and immediately afterwards. The first feeding helps fuel the effort; the second helps recover from it.This advice specifically avoids amounts and measurements because each body handles the different macronutrients fats, carbohydrates, and proteins in a slightly different way.It's up to my teammate as well as those readers who would like to get ultra lean (or just a bit leaner) too to experiment with food types and amounts to create a plan that provides part of the day's nourishment by tapping into the fat stores.