Originally Posted by HarryT
That's I suspect, is talking about benefit for your heart. That's rather different from extended exercise for the purpose of burning calories. 3 minutes exercise a week, no matter how "high intensity" it may be, certainly isn't going to burn many calories
I try to average 3-4 miles brisk walking on a weekday, and perhaps double that at the weekend. It's pounding out the miles that burns fat.
I have to admit to being sceptical about the 3 minute a week claim, too, but there is something in HIIT as concept. For example, a 154 pound person running at a pace of 8 mph burns 320 calories in 20 minutes. That same person, walking at 3 mph for an hour, burns 235 calories. Additionally, the claim is that after a high-intensity session, your body continues burning calories at a higher rate than normal for the rest of the day, and even into the next day.
Also, according to a 2011 study presented at the American College of Sports Medicine Annual Meeting, just 2 weeks of high-intensity intervals improves your aerobic capacity as much as 6 to 8 weeks of endurance training.