Is sitting the new smoking?

Are you sitting comfortably? You may want to stand up after reading this. People are spending so much time on their derrieres it could be shortening their lifespans by up to six years, research suggests. This sedentary lifestyle and lack of exercise is one of the contributing factors to the current obesity crisis.

Michael Mosley, broadcaster and author, explained to Kat Arney why sitting is so harmful to your health, and also explained the concept of 'high-intensity training', the fast way to exercise.

Michael - We spend on average, something like 10 hours a day sitting down. In the good old days, people roamed around a bit and they were much more active in their jobs whereas I don't know about you, but I spend an awful lot of time sitting down at my computer, tapping away. The problem is that, what happens is, the glucose you eat in your meal, it all kind of sits rather sludgily in your body because your muscles just don't get active enough. And there are a lot of studies now which suggest, as you said earlier, that being sedentary is almost as bad for you as smoking. And that you cannot undo the damage you do to yourself in those 8 to 10 hours sitting down by than dashing off to the gym or going for a run.

Kat - As he mentioned earlier, Chris has been standing up for this entire hour. I've been sitting down. What sort of difference has this actually made? For example, has he burned off more calories than me?

Michael - He has burned off some more calories. Not a huge amount but we did a little experiment for a series "Trust Me I'm a Doctor" and what we did was, we got 10 people in an estate agent, we took away their chairs and we got them to stand for around 3 hours a day. We fitted them with accelerometers and we also measured the effects that standing had on their blood glucose after eating lunch and on insulin. There was a big reduction in the levels of glucose. Their glucose returned to normal much faster which is obviously good for diabetes. But they also burned a few more calories and according to our expert Dr. John Buckley when he did the experiment. On basis of this, if you stand for 3 hours a day, 5 days a week, that adds up to 10 marathons a year.

Kat - Wow! Now, I'm feeling a bit guilty because I'm writing a book at the moment and I'm spending a lot of time sitting on my bottom. And lots of people work in offices every day. What can we actually do about this? I see some people who have these very trendy standing desks. How do we get more standing in our lives?

Michael - I think you have to be fairly hard core to do that. I have not quite persuaded myself to get around to it. Lots of the writers used to work standing up, Winston Churchill wrote his speeches standing up and there's a long history of it, but I think it's an acquired thing. Professor Jim Levine from the Mayo Institute is very keen, so keen in fact that he has a sort of treadmill and he works at that.

Kat - That's hard core.

Michael - But even if you simply get up every 30 minutes for 1 minute and walk around, they did the study in New Zealand where they got about 17 normal healthy volunteers and that's what they did. The others sat for 9 hours with brief toilet breaks, or every 30 minutes they would get up and just walk around for 1 minute. And just getting up and walking around for 1 minute every 30 minutes made a substantial difference.

Kat - So, maybe I should set a timer. Should I set a timer if I'm working?

Michael - Yes, absolutely, completely because otherwise you just forget and then you sit there for hour after hour. But set the timer every 30 minutes, get up for 1 minute and indeed, drinking lots of nice cold water is good. You'll burn a few calories, but the main thing is, forcing you to go off to the loo more frequently.

Kat - Now, for people who are gym bunnies, I do like my gym, what is the best way of doing exercise in terms of counteracting the effects of sitting?

Michael - There are two kinds of approaches. The standard one is you go there and you tread your way on the treadmill. I'm personally much more a fan of high intensity training (HIT) and that is becoming extremely fashionable now. And that can be as little as 3 sets of 20 seconds going flat out. That's what I do. I have an exercise bike and it takes me about 5 minutes. HIT, what it does is, it does something which standard exercise just doesn't do. It increases the amount of activity of the mitochondria. It seems to lead to greater fitness faster. I mean, what people who are gym bunnies like to do is they do standard you know, and every so often, you put a little burst in. If you go for a run for example, what you should do if you see a hill is sprint for 20 seconds flat out up that hill, preferably obviously not damaging yourself in the process. But there seems to be something about the intensity which is incredibly important if you want to improve your fitness.

Kat - And for people who have spent maybe most of their lives sitting on their backsides, if they think, "Right! I'm going to start, get up, walking, maybe do a bit of a physical exercise, some high intensity" is it going to make a difference or is it just too late?

Michael - Absolutely! Start any time, any age and it's going to make a difference. We know that doing even say, 20 minutes, if you go from sedentary will increase your life expectancy by around 5 to 6 years which prorata works out at about 40 minutes. So, 20 minutes invested now is worth 40 minutes of longevity. So, it's a good deal.

Kat - I feel like I want to stand up for the rest of the show. Thank you very much. That's Dr. Michael Mosley, science writer and broadcaster.