Don't just sit there
If you are serious about losing weight, don’t take up a gym membership: stand up more often.
Sitting contributes more to weight gain than missed exercise classes, according to Adrian Bauman, Sesquicentenary Professor of Public Health. “We often inappropriately think that a single session of exercise will help us fight obesity, but it’s what we do with the other 23 and a half hours in our day that also counts. The two sides of the equation are energy intake and energy expenditure. You won’t expend much energy in terms of weight control if you are in a seat most of the day, even if you did your recommended 30 minutes of physical activity.”
Bauman concedes that those more intense bursts of energy expenditure do have real health benefits, it’s just that ‘fat busting‘ is not one of them. “Physical activity is important to ward off heart disease, diabetes and stroke. It reduces the risk of breast and colon cancer. It also reduces the risk of falls, which is important for older people, as is the reduction in risk of Alzheimer’s and some forms of dementia. Physical activity is also beneficial for mental health.
“We’ve known for 15 years that we need to be active at a level of ‘moderate intensity’ for about half an hour a day. Just under half the adult Australian population is managing that. “On the other hand, not sitting is important for weight control and reducing the risk of diabetes. The risks of prolonged sitting and physical inactivity are partly independent, so you need to do both,” says Bauman.
For Bauman, sitting may be a potential cause of a new wave of chronic diseases across the world. But there are significant challenges in getting people to change long-standing behaviour. “As we develop knowledge, we realise that things might not be as we have always believed. Fifty years ago, we didn’t know about the harms of tobacco and high cholesterol. Now we realise that we need to have a prudent diet and not smoke if we want to have a healthy long life.”
"The simple act of standing - not even walking - is beneficial."
Bauman points to the reduction in smoking rates as one of the great public health success stories. But then, it has been easier to draw the dots between smoking and lung cancer, and hence to make the case for quitting more compelling.
"We don’t make changes to single risk-factors in isolation, so it is difficult to say how much of an improved health effect is attributable to one change in lifestyle. For example, heart disease can be affected by a whole range of things, from diet and physical activity to smoking and controlling high blood pressure. The exception to that rule is lung cancer, where we know that 85-90% of the risk of the disease is from smoking. The other problem is the long lag-time between developing chronic diseases and the risk factors that precede them. A person can be indulging in a bad diet for 30 years before we see signs of heart disease.”
Rather than sit around waiting to discover if Bauman’s predictions prove right some decades down the track, there’s a very easy way to hedge your bets without too much effort: get up on your feet. The simple act of standing - not even walking - is beneficial.
“When you are sitting or lying, all your muscles are at rest. When you are standing, your large thigh muscles are electrically activated, pushing blood sugar into muscle so that you have lower blood sugar than those sitting down. Prolonged high circlulating blood sugar levels are one pathway for developing diabetes.
“In the past three decades, we have moved into occupations which are increasingly sedentary. We are sitting down all the time. There are fewer manual occupations than ever before. Security guards who used to walk around, now sit in front of monitoring screens; labourers who unloaded ships, now use cranes; and farmers are threshing wheat sitting on tractors. Jobs which involved expending energy are disappearing in all but the poorest countries where active occupations are still common.
"Sitting is pervasive at work and at home, as well as in the cars we drive to and fro. In transitional countries, such as China, where people are working hard and for long hours, we see that a retired 65-year-old sits much less than an employed 55-year-old. The young adults in China and other rapidly developing countries, have changed their morning active commute by bicycle or walking, and now ride motorcycles or cars. This engineers activity out of their lives," says Bauman.
“We need to build activity into our day by using the stairs, walking for short trips, or visiting the office next door to talk to a colleague, rather than emailing them. Students can stand around the sides of lecture theatres rather than sit, and we could conduct standing meetings - there’s no real need to be on a seat during these gatherings.”
As Bauman likes to point out: “There’s nothing biologically or environmentally adaptive about sitting.”
When obliged to sit, would it help to flex your muscles with a bit of fidgeting? He thinks it would be useful but might end up annoying others. For his own part, Bauman has a sit/stand desk, holds some standing meetings, stands during teleconferences, and dictates standing up. “I have done so for years,” he says.
Adrian Bauman is Sesquicentenary Professor of Public Health, School of Public Health, Sydney Medical School.