Research limitations also matter. “Many studies are short, small, and done in young men alone,” says Phillips. “We still need longer trials in women, older adults, and people with obesity, prediabetes, or type 2 diabetes.”
How to approach fasted workouts safely and effectively
For those who choose to work out before eating, how you approach it may matter more than the timing itself. One key is matching your nutrition to your workout. “If the workout is easy and short, fasted exercise is a reasonable option,” Tiller says. “But if the workout is long or hard, eating beforehand is the superior choice.”
Hydration is also important, as it’s easy to overlook fluid intake when skipping out on calories. And refueling afterward matters just as much. “I always recommend eating right after a fasted workout, so that you can replenish nutrients right away,” says Lin.
Most importantly, pay attention to how you feel. Though fasted workouts are generally considered safe, Burke notes that individual fatigue, dizziness, irritability, or declining performance are all signs that fasted training may not be a good fit.
While fasted workouts remain an area of scientific interest, their overall impact remains modest for now—and far less important than other exercise fundamentals. “For most people,” Phillips notes, “the big rocks are exercising at all, doing it well, and eating in a way that supports their goals.”