What is the 12-3-30 weight loss trend? Science breaks down the viral workout that may burn fat for fuel

A treadmill workout that once seemed like just another fleeting social media fad might actually have some science behind it. The 12-3-30 method — walk at a 12% incline, at three miles per hour, for 30 minutes — was popularized by influencer Lauren Giraldo as a low-impact, fat-burning routine. But how does it fare against good old-fashioned running?

A new peer-reviewed study in the International Journal of Exercise Science, highlighted by Fox News Digital, set out to find the answer.

Walking Uphill vs. Running Flat Out

Researchers tested 16 healthy young adults — both men and women — who were already exercising at least three times a week. Each participant completed two workouts:

1. 12-3-30 walking session
2. Self-paced treadmill running for 20–25 minutes

Both sessions were adjusted to burn the same total number of calories so that researchers could compare how each exercise tapped into the body’s energy sources.

The results revealed a clear trade-off:

• Running burned calories faster — around 13 calories per minute, compared to 10 calories per minute for 12-3-30.
• Walking at 12-3-30 relied more on fat for fuel — 41% of energy came from fat, versus 33% during running.

What the Experts Say

Certified personal trainer Maelee Wells Sutton from Crunch Fitness told Fox News Digital that the findings are not surprising.

"Walking at 12-3-30 is certainly more intense than walking on a flat surface, but is less intense than a run," she explained. She also stressed that the study’s participants were already active, meaning the results may not directly apply to beginners or less active individuals — a large segment of the population.

Sutton emphasized an important reminder: total calorie burn still matters more for weight loss than the percentage of fat burned. “The ‘fat-burning’ percentage of a workout is not the same as total calorie burn,” she noted.

Time, Goals, and Consistency Matter

If your priority is to burn a set number of calories in less time, running remains more efficient. But for those who want a lower-impact, joint-friendly workout or a way to build endurance while burning more fat proportionally, the 12-3-30 method offers a compelling option.

Most importantly, Sutton says, pick something you can stick with. “If a person dislikes running but loves 12-3-30, it’s far better to do that consistently than to force a certain workout that a person rarely completes,” she said.

The verdict? The viral 12-3-30 treadmill trend may not replace running for speed and calorie burn, but for many, it can be a sustainable step toward better fitness.