It seems there’s a new headline almost daily about the rewards – and risks – of intermittent fasting. Tales of dramatic, life-changing weight loss and stunning disease reversals are quickly tempered by horror stories of eating disorders, depression, and boomerang weight gain.
Fasting for wellness dates back as far as the ancient Greeks, when Hippocrates reportedly prescribed the practice for patients with certain conditions. Religions around the world still employ fasting as a way to cleanse body, mind, and soul. Intermittent gained traction in health and fitness circles when people began losing weight quickly by restricting their eating to only certain times during the day.
Is intermittent fasting good for runners? We asked Ashely Muschiatti, Performance Specialist and Registered Dietician with Novant Health and Joe Gibbs Racing.
“Even for someone who does not exercise, eating enough calories in that time is hard,” says Muschiatti. “So, you tend to go into a calorie deficit. When you cut meals, cut food, cut calories, you are going to go into a deficit and lose weight. Simple math there.”
But, and there’s always a “but,” Muschiatti warns. Fasting can create brain fog, fatigue, and decreased muscle mass, especially if you are not making sure to get enough nutrients during when you’re eating. Fasting can also foster disordered eating patterns or even social withdrawal and can create unhealthy relationships with food.
At first you may feel good – and many people that do it report feeling fine and energized— but our bodies will go into starvation mode, which can mess with hormones and other processes. Intermittent fasting is not usually a long-term dietary habit, or people do it “loosely” because it is not maintainable. Many times, too, when someone stops intermittent fasting and returns to a more sustainable dietary pattern, the weight lost tends to come back.
Muschiatti says most studies on intermittent fasting have focused on obese patients, and the majority of people trying to incorporate it into their routine aren’t likely aren’t getting enough of the right kind of foods when they do eat. If you plan on trying fasting as a weight loss method, she recommends consulting with a dietitian and make sure you are eating adequate calories and hitting all macronutrient goals. Be cautious if you are exercising during your fasting window as you have a higher chance of becoming lightheaded or passing out due to high exertion with no “gas in the tank.”
Also, be aware if your dietary habits and restrictions are impacting your social life, or creating unhealthy feelings about food and eating, cautions Muschiatti. And understand the side effects. Discuss fatigue, energy levels, mood changes, and any other changes you see with your doctor and Registered Dietitian.
And for runners, Muschiatti posits the same questions she poses to the pit crew at Joe Gibbs racing. “I ask, would you start a race on an empty tank of gas? And they automatically say, ‘No that would be dumb.’ So why would you start your day with an empty tank?”
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