Fez — The 12-3-30 treadmill workout, created by influencer Lauren Giraldo, has amassed over 14 million views online for its simple formula: walk at a 12% incline, at three miles per hour, for 30 minutes. Marketed as a low-impact, fat-burning routine, it has attracted both fitness beginners and seasoned gym-goers.
A peer-reviewed study in the “International Journal of Exercise Science” compared 12-3-30 with “self-paced” treadmill running. Sixteen healthy young adults completed both workouts — one 12-3-30 session and one running session lasting around 20 to 25 minutes — with calorie output adjusted to be equal in both.
The results showed running burned calories faster, averaging 13 calories per minute compared to 10 for 12-3-30. However, the walking workout used more fat as a fuel source, with about 41% of energy coming from fat, versus 33% during running.
Fitness experts note that while the fat-burning percentage is higher for 12-3-30, the overall difference is modest. Total calories burned still play a larger role in weight loss than whether energy comes from fat or carbohydrates.
Walking at a steep incline is more challenging than walking on a flat surface but is still less intense than running. For those with joint issues, beginners, or anyone preferring a lower-impact option, 12-3-30 can be a sustainable choice.
Researchers emphasize that workout selection should depend on personal goals and consistency. Running may be more efficient for quick calorie burn, while 12-3-30 offers a joint-friendly option that engages fat metabolism slightly more.
Both approaches can be effective if performed regularly. Experts advise choosing the workout you are most likely to stick with, rather than forcing an activity you dislike.
