Do you know how to prep your body for a workout, including what you should eat before, if anything?
On social media, many people praise fasted workouts for their alleged health benefits, such as extra fat burning and weight loss
But dietitians caution that exercising on an empty stomach can be risky and the evidence to suggest it has any benefits is limited
Expert Tip of the Day: Fasted Workouts Are Not Better for Fat or Weight Loss
“Fasted exercise does seem to increase fat burning during the workout itself,” Joy Bauer, dietitian and TODAY contributor, tells TODAY.com. “When you haven’t eaten, insulin levels are lower and your body is more likely to tap into stored fat for fuel. But here’s the important distinction: Burning more fat during one workout does not necessarily mean you’ll lose more body fat over time.”
TODAY nutrition editor and dietitian Natalie Rizzo agrees: “There’s little evidence that exercising on an empty stomach leads to greater weight loss than exercising after eating, as long as total calorie intake and exercise are similar.”
In fact, eating before exercise may give you the energy to burn even more calories and build more muscle, Rizzo adds
Why It Matters
It’s important not to try every trend you see on social media just because influencers say it works, as some come with health risks
“Research suggests there may be some metabolic benefits with fasted exercise, including adaptations related to insulin sensitivity, but for most people, the biggest drivers of weight management are still the overall quality of their diet, how much they’re eating, and most importantly, whether they exercise consistently,” Bauer explains
How to Get Started
Rizzo and Bauer offer a few guidelines for determining if you should eat before exercising
“I usually tell people to eat before almost every workout. But if you want to exercise in a faster state, then consider three things: the workout, the timing and how you feel,” Rizzo says
“If you’re doing an easy walk or gentle yoga first thing in the morning and you naturally feel fine without eating, it’s probably OK to exercise fasted. But if you’re lifting weights, doing HIIT, running, cycling or any other endurance sport, having some carbohydrates beforehand is beneficial and recommended.”
Bauer compares fueling for a workout to a road trip. “If you’re taking a quick spin around the block, you probably don’t need a full tank of gas, but if you’re headed out on a long haul, you don’t want to start on empty,” she says
The dietitians say fasted workouts can actually be dangerous for certain groups:
- Anyone taking insulin or a medication that can lower blood sugar, such as people with diabetes
- Pregnant people
- Anyone with a history of fainting or low blood sugar
- Anyone with a history of disordered eating
- Anyone training multiple hours a day with high caloric needs
If you decide to try a fasted workout, pay attention to how your body is feeling. “Feeling a little challenged during exercise is normal; feeling faint, disoriented or unable to control your body is not,” Bauer says
Signs you need to take a break and refuel include “dizziness, lightheadedness, shakiness, unusual weakness or even lack of physical enthusiasm to work out, nausea, cold sweats, blurred vision, confusion, trouble concentrating or a sudden drop in coordination or performance,” Bauer explains
In this case, sit or lie down and have 15-20 grams of a fast-acting carb, such as juice, a sports drink or piece of fruit. “Give yourself about 15 minutes to recover, and don’t resume exercising until the symptoms are completely gone,” Bauer adds
