If you were sceptical of the viral 12-3-30 treadmill workout, a new study directly comparing it to running has found that it burns more fat – despite expending the same number of calories. Published in the International Journal of Exercise Science, the authors note, ‘This is the first study to directly compared metabolic responses between 12-3-30 and self-paced running.’
As the 12-3-30 workout goes, participants walked at a 12% incline at 3mph (or 4.8kmph for UK treadmills) for 30 minutes, with no handrail holding allowed; their runs were self-paced, stopping once their total calorie burn matched that of their 12-3-30 workouts (they each performed one 12-3-30 workout and one run within a seven-day period). Researchers then measured whether participants sourced more of their energy from fat or carbohydrates while exercising, and the results showed that running burned 33% of its calories from fat, while incline walking burned 40% from fat.
This won’t be a surprise if you’re familiar with heart rate zone training – zone 2 training at 65-75% of your max heart rate, like incline walking, uses fat as your primary fuel source over carbohydrates. As your heart rate increases, you switch from your aerobic energy system to your glycolytic energy system and begin to use carbs for energy. But for many, the study’s findings go against the common belief that high-intensity workouts are best for fat burning.
Incline walking is more effective for fat burning than running, study confirms
While running triggered a faster (but not bigger) calorie burn, it relied more heavily on carbohydrate stores for fuel. Incline walking, at a lower intensity than running, showed that the body’s fuel preference was fat. It’s a no-brainer if you’re aiming to preserve muscle mass and glycogen stores while maximising fat loss, particularly if you’re training in a calorie deficit and need to conserve energy.
But there are a few limitations to be aware of. The first is that the study had a small sample size of just 16 participants (seven female, nine male), though the authors note that this is ‘large enough’ to corroborate the findings.
Secondly, if you’re short on time – and less bothered by where you burn calories from, it’s worth noting that running burned the same number of calories in 23 minutes, seven minutes faster than incline walking. Body recomposition – preserving and building muscle while burning fat – is important for everyone, but anyone significantly overweight may benefit from starting with running to achieve a negative energy balance, which the study’s authors note is the ‘main determinant for weight loss’.
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Of course, if the idea of walking on a treadmill for 30 minutes fills you with as much dread as five office days every week, you probably won’t hit your goals. Finding something you enjoy and will stay consistent with is crucial – but if fat loss is your goal, even one incline walk a week could help.
How to do the 12-3-30 workout
- Set your treadmill incline to 12%
- Set your speed to 3mph (or 4.8kmph)
- Walk for 30 minutes
12-3-30 workout safety tips
We asked fourfive ambassador and celeb PT Jenny Francis-Townson:
Who is the 12-3-30 workout good for?:
- People with a good fitness base who want to ‘tune out to the world’
- People who are prone to injury/joint pain and will benefit from low-impact movement
Who should avoid the 12-3-30 workout?:
- Beginners, since ‘it’s certainly a challenge and will put a lot of strain on your body’. Start with 10 minutes at 4% incline once a week. After a month, increase by 2% and five minutes and continue doing so every two weeks
- Those who are already suffering with knee or lower back problems
As Women’s Health UK’s fitness director (and a qualified yoga teacher), Bridie Wilkins has been passionately reporting on exercise, health and nutrition since the start of her decade-long career in journalism. She secured her first role at Look Magazine, where her obsession with fitness began and she launched the magazine’s health and fitness column, Look Fit, before going on to become Health and Fitness writer at HELLO!. Since, she has written for Stylist, Glamour, Cosmopolitan, Marie Claire, Elle, The Metro, Runner’s World and Red.
Now, she oversees all fitness content across womenshealthmag.com.uk and the print magazine, spearheading leading cross-platform franchises, such as ‘Fit At Any Age’, where we showcase the women proving that age is no barrier to exercise. She has also represented the brand on BBC Radio London, plus various podcasts and Substacks – all with the aim to encourage more women to exercise and show them how.
Outside of work, find her trying the latest Pilates studio, testing her VO2 max for fun (TY, Oura), or posting workouts on Instagram.