It’s cold, the hours of sunlight are short and if you’re not already a committed runner, chances are not every second of your time pounding the pavement is a pure, unrestrained pleasure. Along with all the life-admin thoughts and qualms that pop into your head while running, the question that accompanies every stride is: Should I be going hard or taking it easy? Two deeply qualified experts were on hand to end the debate.

Short vs long-distance running

Josh Kerr, a UK-based runner, and the 1500m world champion, says, “The short, sharp bursts make a big difference, that’s what’s going to get things going a little bit quicker, with the high heart-rate it’s gonna take less time, which may help you get out the door.”

However, he also concedes that if you want to fall in love with running, you need to first "go out and run slow and enjoy all the aspects training brings, staying away from the screens and getting out into nature and enjoying it.”

As he takes a break from altitude training in Albuquerque, Mexico, the word Kerr comes back to is “longevity” – he says the best approach is the one that you will stick to.

We ask him to imagine a man in his thirties, a former sports enthusiast with reasonable fitness who is looking to slim down. “Anyone with a background in sport will be competitive with themselves, so you’ve got to be aware of that," he says. "The slow miles approach will never engage them that much, so little mini-interval sessions will be important.”

A weekly plan that includes Fartlek

Kerr suggests Fartlek (timed bursts at different paces) along with slower runs for as long as you can manage. He is (coincidently) currently coaching his brother, who's a rugby player, and this is his recommended week:

Monday and Tuesday: Easy runs with some hill sprints at the endWednesday: Fartlek trainingThursday: Day off Friday: Five-mile run Saturday: Hill running Sunday: If working towards a marathon, a long run

If you are thinking of a cut-to-the-chase version of this and plan to run intensely every day can we politely suggest you don’t? Kerr says the Fartlek intervals are hard, and therefore, twice a week is the recommended max. It's a view very much in line with Taren Gesell, an endurance sport coach and founder of the Canadian Mottiv training company suggests.

Short hard bursts can pay off

“I had a really hard time losing weight sustainably. I tried bodybuilding-style workouts, I tried various diets–I was able to get down to about 190lbs, but it was a big struggle. The thing that finally got the weight loss to stick and get down to losing a total of 65 lbs was a mixture of mainly low-intensity workouts and then once, or possibly twice, a week very high-intensity workouts.”

A study carried out in New South Wales found that a group of young men defined as carrying excess weight experienced ‘significant reductions in total, abdominal, trunk and visceral fat’ after 12 weeks of 20-minute, intense interval sessions three times a week.

There are a number of ways in which it does this, says Gesell, echoing Josh Kerr, but it’s really hard on the body, so that kind of training would wear you out and injure you if you attempted it every day.

“When you do most of your training at an easy pace, you burn a lot of calories during those running efforts, and they help you undertake the intense sessions much more safely. Your cardiovascular fitness and general foundation are able to withstand HIIT training more easily.”

Gesell tells us that intense exercise has been found to burn between five and 15 percent additional calories after exercise has ended, but the overall effect remains a mystery with a whole range of reasons potentially in the mix, including changes in insulin sensitivity and adaptations in the muscle tissues themselves.

On pure calorie burn, he says: “You use more calories on a steady run, but consistently in studies, high intensity wins on fat burn.”

So, the final answer to the question of short runs vs long runs for fat disposal is short and fast every time – both experts agree. But you can’t really do it every time.  At the risk of sounding like a politician in a marginal seat, there are strong arguments on both sides of the debate, and the middle way is best.

Phil Hilton was the one of the first UK editors of Men’s Health magazine in the 1990s and now writes about midlife fitness, body image and ageism for publications including The Times, The Telegraph and The Guardian. He has lifted weights, trained in martial arts and experimented with all kinds... Read moreXInstagram