Sitting is the new smoking.

Get used to that expression because you're going to be hearing it a lot. Inactivity has become public enemy No. 1.

The reason sedentary behaviour is so worrisome is well-illustrated by a new study, published on Monday.

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The research, led by Dr. Emma Wilmot of the diabetes research group at the University of Leicester in Britain, analyzed 18 existing studies involving almost 800,000 people. The paper, published in the medical journal Diabetologia, compared disease rates between the most active and least active among a broad cross-section of adults.

The researchers found that the least active, essentially those who sit all day, had a:

147-per-cent increased risk of heart attack or stroke;

112-per-cent increase in the risk of developing diabetes;

90-per-cent greater risk of dying from a cardiac event;

49-per-cent greater risk of premature mortality.

Those are sobering numbers, especially when you consider that the average Canadian adult spends 50 to 70 per cent of their daily lives sitting, and roughly another 30 per cent sleeping.

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Do the math and you quickly realize that between sitting in our cars, sitting at our desks at work, sitting in front of the TV, sitting in front of our games consoles, sitting to eat, sitting in school, we hardly move any more.

And there is good evidence that inactivity now kills more people than smoking each year.

We have engineered activity out of our daily lives and it's taking a real toll on our health, individually and collectively.

In recent years, the focus has been on the staggering increase in the number of people who are overweight and obese. That discussion was refined a bit with an emphasis on belly size and waist-to-hip ratio – recognition of where we put on weight matters.

But weight is only part of the story. You can be fat and fit, and you can be thin and unfit.

What is highly unlikely is, regardless of your body shape, that you are sedentary and healthy.

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Activity really matters – to your heart, to your brain, to your bones and to your sexual health.

It's important too to recognize what activity means. It's about moving. You don't have to run a marathon every day to derive health benefits.

Ideally, you should be moderately active – the equivalent of a brisk walk – 30 to 60 minutes a day, every day.

Very few people are meeting that minimal standard. According to Statistics Canada, only 15 per cent of adults and 7 per cent of children meet the minimum recommended physical activity guidelines every day. Those are the most active people in modern society, and they're not that active.

What is even more important than this planned activity is what researchers call "light ambulation" – moving around at regular intervals instead of remaining on your duff.

Exercising like a maniac for an hour a day isn't going to offset 23 hours of being sedentary. But breaking up your sitting with activity, even very light activity, can have a significant impact.

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Take this example, from Dr. Wilmot's paper: Prolonged sitting sharply reduces glucose and insulin secretion, key factors in developing diabetes. But these changes can be offset by standing up and walking two minutes for every 20 minutes of sitting. This is true even in obese people.

What this means, practically speaking, is that even if you watch TV for hours at a time, if you get up and walk during the commercials, you will be doing your heart a big favour. Sure, it's even better if you switch off the TV and take the dog for a walk but a little effort matters.

Similarly, office workers, can offset much of their risk by taking a short walk every half-hour, or by having a standing desk, or even by sitting on an exercise ball. (Research shows they will also be more productive.)

There are four main components in activity: domestic physical activity, work-related activity, transportation-related activity and exercise. In the past generation or two, levels of activity in each of these areas have fallen sharply – except exercise.

From time immemorial until a decade or two ago, almost all physical activity occurred on the job. The number of people doing manual labour has plummeted, while the number of people in white-collar jobs has soared.

Manual tasks in the home have also largely disappeared. We vacuum instead of sweep; we have dishwashers instead of washing dishes by hand; we have tractors to cut the lawn. And so on.

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Almost all our transport is now by car. Fewer than 10 per cent of people walk or take public transport to work. The same is true of kids – 90 per cent are transported to school; they don't walk or bike.

There is a small – but growing – minority of the population that exercise. They run, they swim, they do CrossFit or spinning or whatever the latest fad exercise is.

But we are not going to exercise our way out of the real health crisis – sedentary behaviour or, more accurately, sitting disease.

The solution is simple movement, a little bit at a time, incorporated into our daily lives.

In short, we need to re-introduce a dose of inconvenience into our lives. But we need to think of it not as inconvenience but as a few steps to a better life.