A new study suggests that the viral 12-3-30 treadmill workout, which went viral on TikTok by influencer Lauren Giraldo, may burn more fat than traditional treadmill running, even though it takes longer to complete.
The 12-3-30 workout is simple. All you need to do is set your treadmill to a 12 per cent incline, walk at 3 miles per hour, and continue for 30 minutes. Giraldo, who introduced the workout to millions on social media, claims she lost 30 pounds (13 kgs) without strict dieting. A new study by researchers at the University of Nevada, Las Vegas, compared the 12-3-30 workout to self-paced treadmill running in 16 adults, analysing calorie burn, fat and carbohydrate use, and exercise time.
Why the 12-3-30 went viral
Fitness trends keep changing every now and then. We’ve seen everything from aerobics in the ’80s to Zumba in the 2000s. But with social media, new workouts are spreading faster than ever. Giraldo’s video showcasing her routine has now been viewed more than 14 million times on TikTok.
In the clip, she explains how the routine helped her lose weight and stay fit without obsessing over calories or spending hours at the gym. Many people agreed with her, saying the workout felt easy to follow and less scary than running or intense exercise. But without scientific proof until now, the question remained: does it really work or is it just another TikTok trend?
Study findings
The study, published in the International Journal of Exercise Science, involved 16 participants (7 women, 9 men) who completed both a 12-3-30 session and a self-paced treadmill run in a lab.
Both sessions were designed to burn the same number of calories, ensuring a fair comparison. Researchers measured:
- Completion time
- Energy expenditure rate (how quickly calories were burned)
- Substrate utilisation: Whether calories came mainly from carbs or fat
The study found that running helped people burn calories more quickly. But the 12-3-30 workout made the body use more fat for energy. Participants spent more time exercising during 12-3-30 but ended up with a higher percentage of calories coming from fat.
Why 12-3-30 could help you burn more fat
“Running gets you to the finish line faster, but incline walking seems to recruit more fat for fuel,” the researchers explained.
Scientists say that while overall calorie burn is the main driver of weight loss, the type of fuel your body uses can also matter, especially for people looking to reduce body fat rather than just lose weight.
The study found participants used about 7.5 per cent more fat for energy during 12-3-30 compared to running. On average, 40 per cent of their energy came from fat during the incline walk, versus lower levels during the run.
Why 12-3-30 works slower but smarter
The 12-3-30 workout took significantly longer to complete than the self-paced run. For busy people, running may be a faster way to burn calories.
“If efficiency is your goal, running may be the better option. But if you want a lower-impact exercise that encourages fat burning, the 12-3-30 could be a smart choice,” the authors revealed.
Why does incline walking work better?
Experts say incline walking forces the body to work harder against gravity, increasing muscle activity in the legs and glutes. This extra effort explains the higher fat utilisation compared to running on a flat treadmill.
Earlier research had already shown that incline walking burns more calories than flat walking, but this is the first peer-reviewed study directly comparing the viral 12-3-30 to running.
What experts are saying
Fitness trainers say the findings make sense. “Incline walking is less jarring on the joints than running and is easier to stick with long term,” shares Dr. Jennifer Lee, a sports medicine specialist not involved in the study. “For beginners or those who dislike running, the 12-3-30 could be a great way to stay consistent.”
However, she cautions that consistency matters more than the specific workout. “It’s less about whether you walk or run, and more about finding something you can do regularly.”
So, should you try 12-3-30?
If you’re healthy, enjoy walking, and want a fat-burning workout, experts say the 12-3-30 can be a good choice. Just make sure to:
- Start slow and build up if you’re new to incline walking
- Use proper footwear to avoid strain on your knees and ankles
- Pair it with strength training for balanced fitness
- Listen to your body, especially if you have pre-existing joint issues
The study’s authors reveal that long-term effects weren’t measured, so more research is needed to see if the fat-burning advantage translates to actual fat loss over months.
The 12-3-30 treadmill workout isn’t just a viral TikTok trend, it now has scientific evidence backing its fat-burning potential. While it may take more time than running, it offers an accessible way to burn calories.