Post-Workout Refueling: Now Or Later?

If you're trying to shed some fat, eating less—or not at all—after a workout might be better for your body. Photo:

How disobeying a common rule of nutrient timing can help you reach your race weight.

If you’re having trouble losing fat and getting down to your optimal “race weight” this season, then you’re not alone. Among the endurance athletes I work with (both recreational age-groupers and elite-level athletes), one of the most difficult balancing acts is to solve the conflict between consuming more calories to completely fuel your muscles and improve/maintain performance and eating less to induce an energy deficit and encourage fat/weight loss. Go too far toward “fueling” and you don’t lose weight and go too far toward “cutting” and your performance suffers. So, how do you find the right balance point between fueling enough and not enough (or too much)?

Much has been made over the past few years about the importance of nutrient timing—which most of the time is interpreted as fueling immediately (or at least as soon as possible) following a bout of training. The general idea here is that your body is better able to replenish muscle and liver glycogen stores if you consume a blend of carbs/protein as soon as possible following exercise (for a variety of metabolic reasons including blood flow, enzyme activity, etc). True enough—but do you really need to be doing that? If your main objective is to fully restore glycogen levels for another high-intensity workout later in the day or the following day, then maybe you do need to fuel right away. If, however, you’re like most non-professional endurance athletes, and your main objective is to maximize weight/fat loss (to enhance performance later in the season), then the answer might be that you should not be fueling immediately after exercise.

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This recommendation goes against a great deal of what many age-groupers hold as common knowledge. You’ve been taught to slurp a carb gel before, sip a carb beverage during, and chug a carb/protein shake after your workouts. In doing so, you’re certainly enhancing your replenishment of glycogen—but you’re also reducing your body’s ability to burn fat and your ability to achieve your optimal race weight. In metabolism research, there is a saying that “fat burns in the flame of carbohydrate”—meaning, optimal fat metabolism occurs when some carbs are being metabolized (certain breakdown products of carbohydrate metabolism are needed as cofactors for cellular fat metabolism). The problem is that the constant supply of carbs before/during and especially after training reduces insulin sensitivity and reduces our ability to use fat for fuel and thus our ability to lose body fat. When your glycogen stores are stuffed full, as they are when you’re constantly fueling before/during/after training, there is nowhere left to store more glucose, so we burn it in preference to fat. If you can’t burn fat, you can’t lose fat.

A useful approach for many endurance athletes who are trying to lose those last few pounds to get them to their race weight is to simply stop eating after their workouts, because doing so will improve insulin sensitivity and enhance fat-burning and weight loss. If you’re a bodybuilder or a Tour de France rider or have aspirations of finishing on the podium at the Ironman World Championship, then you’re probably training hard enough and often enough (at least twice daily) that you’re already at your optimal body fat level and you can (and should) eat (and eat a lot) immediately after every workout.

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But even very good and highly competitive endurance athletes probably do not need to fuel immediately after their workouts—unless they’re already at your optimal race weight and have no need to shed any body fat. Instead, save the immediate post-workout fueling for after your most epic workouts (when you really need to maximize your glycogen replenishment) and instead allow your body to use that post-exercise period to benefit from enhanced fat metabolism. Eating later (2 or 3 hours later at your next meal) will still result in replenished glycogen stores—at least to a level that is enough to adequately support the typical training regimens for most recreational endurance athletes—and you’ll notice a gradual and progressive drop in body fat (with the same training regimen) that may have been eluding you previously.


About The Author:

Dr. Shawn Talbott is an avid iron-distance triathlete and ultrarunner. He holds a MS in exercise science and a PhD in nutritional biochemistry and develops products and programs for endurance athletes in a variety of sports.

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