Super-short workouts sound fantastic. Who wouldn't want to pack 60 minutes worth of exercise into just 20 minutes — or sometimes even less? But whatever those short workouts do for your fitness, they're not going to burn the same amount of energy as a longer session, which means they won't help with weight loss.
Photo by NOAA's National Ocean Service
Amby Burfoot, writing for Runner's World, decided to take a look at the numbers.
You can't get 60 minutes worth of calorie burn from seven or four minutes worth of exercise.
The maths doesn't even come close. Any runners who exchange their four-times-weekly six-mile runs for four seven-minute workouts are going to burn at least 1000 fewer calories per week. Which will lead to a weight-gain of 12+ pounds in a year. Minimum. In one year. Try multiplying that by a couple of years.
And if you gain 12+ pounds a year, there's no way your endurance fitness or health is going to be better than it is today. No way. So what exactly have you gained by following a "scientific 7-minute program"? Beats me, though I think you'll probably have stronger quads, if that turns you on.
Shorter workouts can do a lot for your muscles, but if you seek weight loss you really need a good diet you can follow and exercise that will consume more emergy. Eating less is the simplest way to reduce weight/fat, and compact exercise routines can help build muscle, but you shouldn't expect them to make you slimmer. You'll only get more bang for your buck with that approach. Otherwise, you have to put in the time.
Why I Love Shortcuts … And Why They Don't Work [Runner's World]