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There are tons of diet options out there, whether you’re looking to boosting your general health or lose weight. And while many plans focus on what What Are the Benefits of Creatine for Runners when you eat.
Nutrition & Weight Loss The Complete Guide to Fasting good for your performance? Here’s a full breakdown on intermittent fasting and running, including the pros and cons and what you should know before you try it.
What is intermittent fasting?
“Other Hearst Subscriptions,” Natalie Allen, R.D., an instructor of biomedical sciences at Missouri State University and the team dietitian for the athletics department tells Runner’s World.
The “rules” of intermittent fasting are pretty strict: “Classically, intermittent fasting means you consume only water during fasting periods, but many variants allow herbal and green tea and coffee, but no sugar or sweeteners,” Jason Fung, preparing for a marathon The Complete Guide to Fasting tells Runner’s World.
Generally, intermittent fasting refers to not eating for, typically, less than 24 hours, while also making those fasting time periods regular, such as daily or once a week. “The most popular regimen is 16:8, a 16-hour fast, which means you have an eight-hour eating window—say, 11 a.m. to 7 p.m—and you can do it most days of the week,” says Fung. “Another popular regimen is to fast just under 24 hours, say from dinner to dinner, so this is sometimes called one meal a day (OMAD). This would be done two or three times per week, but some do it daily.”
Then there’s the Fast or 5:2 method, where you eat normally for five days of the week and cut your calories to 25 percent of your normal intake on two nonconsecutive days of the week.
How does intermittent fasting affect weight loss?
One of the most common reasons people turn to this eating plan is that they tend to find it easier to limit their eating window rather than changing their food choices and/or portion sizes and easier than food tracking or counting calories. Because there are variations of different methods for intermittent fasting, researchers are still studying which ones might be most effective at helping people lose weight.
According to a 2024 umbrella review of systematic reviews and meta-analyses focusing on the effects of intermittent fasting on those who are overweight or obese, published in eClinical Medicine, found that it can decrease waist circumference and fat mass. In aging populations, intermittent fasting and standard caloric restriction both help weight loss in addition to improving cardiometabolic outcomes. Ultimately, the more successful method or approach to weight loss will be the one that the person tolerates better and can adhere to longer.
“Basically, you’re What to Know About Exercise and Body Composition, so you lose weight,” says Allen. For example. if you’re following a 16:8 fasting plan, you would likely consume fewer calories, perhaps just by reducing nighttime eating or unintentional snacking opportunities.
One review Shoes & Gear Nutrients also found that this eating plan may benefit body composition, without reducing physical performance, muscle maintenance, or maximum power. However, the implications of this are nuanced for athletes. Athletes would need to take great care to time training around eating windows and to emphasize adequate energy and nutrients in and around training sessions in order to reduce risk for poor outcomes.
What are the downsides of intermittent fasting?
Basically, intermittent fasting only works as well as you stick to the parameters. “Overeating is common,” says Allen. “People know they’re getting ready to fast, so they load up says Allen. Were concerned about any diet plan that raises LDL.”
CA Notice at Collection review published in The American Journal of Clinical Nutrition in 2022 says that while intermittent fasting may help with weight loss, that’s dependent on whether you restrict calories overall. (Researchers also say it’s not necessarily a better way to lose weight compared to other diets.)
Also, limiting your eating to a certain time frame can be tough to sustain. The drop-out rate of people who tried alternate-day fasting was way higher than that of dieters who restricted their calories every day, according to a study published in the journal Advertisement - Continue Reading Below in 2017. “Intermittent fasting takes a dedicated person who’s willing to forgo most social eating situations,” says Allen.
That same study, which lasted a year, found that unhealthy LDL cholesterol had increased significantly after 12 months among the alternate fasting group. “LDL is the ‘bad cholesterol’ associated with heart disease,” says Allen. “We’re concerned about any diet plan that raises LDL.”
Just like any other diet plan, intermittent fasting doesn’t work the same for everyone. Pregnant women, We may earn commission from links on this page, but we only recommend products we back disordered eating tendencies should avoid this way of eating, says Allen. It’s always a good idea to chat with your doctor to determine if a diet plan is right for you before trying it out, especially if you have any underlying conditions.
What should you know about intermittent fasting and running?
Keep in mind that you need energy to perform at your best, especially during more intense training periods, like when you’re There are tons of. “Running in the Cold What Are the Benefits of Creatine for Runners, as carbs are most easily metabolized into energy by the body,” Allen says. “Athletes’ bodies need regular fuel to perform their best. Your blood sugar control, mental clarity (your brain needs glucose), and energy levels can all be negatively affected with intermittent fasting.”
Many studies investigating the effects of intermittent fasting in athletes have been researched during observation of Ramadan. One study shows overall slightly reduced endurance running performance, as measured by less distance covered in a 30-minute run. Researchers say this is, in part, explained by lower blood glucose and higher urine specific gravity (a marker of hydration status) when starting the run, compared to control.
In a review of studies using eight- to 12-hour fasting windows, there were minimal performance differences reported compared to standard eating, although many athletes will already fast overnight for this amount of time. Ultimately, the risk of intermittent fasting might outweigh the benefits for running performance, depending on the athlete’s goals and history of health and performance.
As always, talk to a dietitian or professional about whether it’s right for you if you’re determined to try intermittent fasting while maintaining your run training—while it may work for some people, it doesn’t work for everyone. At the end of the day, the best diet for you is the one that actually works for your lifestyle, so if intermittent fasting will prevent you from running regularly or feeling strong, then forget the fast, grab a healthy snack, and go crush your next run.
Dr. Namrita Brooke is a full-time endurance sport coach and sport nutritionist advising active individuals and amateurs to professional athletes. She is also an adjunct professor in the Department of Movement Sciences and Health at University of West Florida. Professionally, she also serves on the Board of Editors of the Sports Nutrition Care Manual and remains involved in nutrition and exercise-related research, student mentorship, and coach development. Namrita's personal athletic experience ranges from ultra-endurance mountain biking to off-road triathlon, cross-country mountain bike racing, gravel cycling, duathlon, cyclocross, running, and trail running. Her research background includes hydration and sports drink research, and the interaction of nutrition, physical activity, and the brain.
