HomeHealthSugar: Your Body’s Friend or Foe?

    Sugar: Your Body’s Friend or Foe?

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    Of all the questions rowers ask me, “What about sugar?” is at the top of the list. It’s likely you’ve have been bombarded with messages that sugar is evil, feeds cancer, causes obesity, ruins health, and should be avoided at all costs. It’s likely also you’ve heard that sugar fuels muscles during exercise, is the main ingredient in commercial sports foods, and enhances recovery from hard workouts. So let’s look at some sugar myths and misconceptions as well as new technology that can measure your personal response to sugary foods.

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    Is sugar addictive?

    No. While sugar lights up pleasure centers in the brain, sugar is not an addictive drug like cocaine. Sugar cravings can often be curbed by preventing hunger. Hunger triggers cravings for sugary foods and the urge to overeat. Hungry rowers can devour a lot of gummy bears or Oreos in the blink of an eye.

    If you believe you’re addicted to sugar, try this experiment: Rearrange your eating patterns to enjoy a king-sized high-protein breakfast (three-egg cheese omelet + Greek yogurt + fruit + granola) followed by a satisfying protein-rich lunch (peanut butter & banana sandwich + glass of milk), and you’ll notice quickly your afternoon and evening sugar cravings dissipate (that is, unless you’re eating to manage stress and smother feelings—as opposed to enjoying food for fuel).

    Is sugar fattening?

    No. Excess calories of any type are fattening. Many athletes tell me that despite eating only “healthy” foods (i.e., no sugary sweets), they’re not losing weight. They simply could be swapping 100 calories of gummy bears for 100 calories of grapes or 100 calories of nuts. No calorie deficit there.

    The conversion of excess calories of sugar into body fat is actually tough (as compared to the conversion of excess calories of dietary fat into body fat). Sugar often comes with fat (cookies, ice cream, chocolate); therefore, overeating gummy bears could be less fattening than overeating fatty chips. (But first, curb the urge to overeat sugary-fatty foods by enjoying a king-sized breakfast.)

    I’ve heard sugar feeds cancer cells. Should I avoid sugar to reduce my risk of getting cancer?

    No. Sugar feeds all cells, not just cancer cells. Giving sugar to cancer cells does not make them grow faster, nor does depriving them of sugar curb their growth. A diet rich in fruits, veggies, and whole grains reduces the risk of cancer—even though these foods all end up as sugar in your blood. (Yes, all grains and plant foods—all of which are carbohydrates—digest into sugar.) Sugary foods can be linked to obesity, and obesity can be linked to cancer. Cancer patients who are prescribed prednisone as part of their treatment may need to limit sugar because the medication can elevate blood sugar, but that’s a different story.

    Does sugar cause diabetes?

    No. Type-1 diabetes occurs when the pancreas makes inadequate insulin to transport sugar out of the blood and into the muscles. Type II diabetes occurs when the muscles don’t respond to insulin normally. This happens often with people who are fat and unfit. In comparison, most athletic people maintain normal blood-glucose levels.

    Should rowers be concerned about “sugar spikes”?

    Generally, not. After you eat any type of carb (fruit, veggie, grain, sugary or starchy food), your blood sugar (blood glucose) will rise as the sugar moves from your gut into the bloodstream. Blood glucose gets used by the brain, the liver, muscle, and internal organs. This “spike” is a normal response, and the body has a complex system of checks and balances to keep it within a normal range—between 70 and 180 milligrams per deciliter (about three ounces). After hard exercise, a spike in blood glucose is a normal physiological response.

    Will monitoring my blood-sugar level help me perform better?

    Some rowers are measuring their sugar levels with a continuous glucose monitor (CGM). The device is sort of like a fuel gauge that can help them figure out if they are under-fueled. This knowledge might inspire rowers who under-eat to fuel better to perform better, but we need much more research to validate this hypothesis.

    Most research with CGMs has been done on people with diabetes. They need to know whether their blood glucose is too low (causing shakiness and hypoglycemic sweats) or too high (causing damage to tiny blood vessels in the eyes, kidneys and other organs, which can lead to such long-term complications as organ failure and blindness). For them, CGMs can be health-saving, whereas for athletes the data are more a matter of curiosity.

    How does a CGM work?

    To the back of her arm, an athlete applies a sensor, a small circular adhesive patch with a thin filament that slips under the skin painlessly and measures glucose between cells. The sensor connects to a cell-phone app that collects the data. The technology can determine whether fatigue is related to low glucose and inadequate fuel.

    While a CGM can help you learn about your body’s response to carbs, listening to your body’s messages—not looking at numbers on your cell phone—is the better way to go. Simply pay attention to how you feel: Are you droopy? Edgy? Unable to focus on the task at hand? If yes, you’re likely low on fuel, and your glucose is low.

    I enjoy technology (heart-rate monitors, sleep trackers, GPS watches). Where can I buy a CGM?

    Search online or go to a drugstore. Two popular brands are FreeStyle Libre and Dexcom. offers abundant info.

    Before FOMO (Fear of Missing Out) nudges you to jump on the bandwagon, be sure this would be a smart choice for you. Some athletes feel driven to monitor their glucose levels obsessively, which can make them stressed and “glucorexic.” CGMs are used best for one to two weeks by athletes who have a specific performance problem they want to resolve, such as why they feel so tired 25 minutes into a steady-state erg session. A CGM can identify a need to adjust food intake. Will this enhance performance? Stay tuned for more research with rowers. 

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