According to one expert, your workouts aren't doing much for your waistline.
Exercising to lose weight is a waste of time and the only way to shed those unwanted kilos is to eat less. After years of studying kilojoule tables, Sydney exercise specialist John Glynn says it would take seven hours of walking every day for a week to lose just one kilogram and only then if the person ate no "bad" food the entire seven days.
That's distressing news for those who hit the gym or pound the pavement to squeeze into that little black dress for a special occasion. His findings are backed by research, but what has the medical profession concerned is that people might interpret his claims as a green light to stop exercising altogether.
And Glynn's assertion that we only need to exercise for 15 minutes two or three times a week flies in the face of national recommendations to exercise for 30 minutes a day - recommendations the medical profession stands by. Glynn says there are different types of exercise and, while undoubtedly physical activity is necessary for cardiovascular fitness, muscle strength, metabolism, core stability, posture and body shape, it's useless for losing weight.
According to guidelines for the management of people who are overweight and obese, published by the National Health and Medical Research Council, studies show a modest weight loss with physical activity alone of only 1.8 kilograms over a year doing three to five hours of moderate or vigorous exercise each week.
Exercise vs diet
But when that exercise is combined with a cut in kilojoule intake, the weight loss can be as high as 7.5 kilograms in just 12 weeks. While diet is more effective for short-term weight loss, evidence suggests a continuing exercise program outweighs the value of diet in the maintenance of weight loss over two or more years.
"In a second or two we can easily eat hundreds of kilojoules - which overweight people do - and it would take hours to exercise those off," Glynn says. "The right food choices can reduce our kilojoule intake by thousands every day. It would take over five or six hours of exercise to get the same benefit. "Each person has their own unique kilojoule reference point, which is the most kilojoules they can eat in a day and still lose weight without the need for any extra physical activity."
Glynn says that those who exercise to lose weight also tend to pay less attention to their diet, which makes it even more difficult for them to lose weight.He also says exercise for weight loss is a serious long-term health risk because of the added load on the body's organs, and that thin people need to exercise more than those who are overweight.He argues that for years health professionals have misled Australians about the value of exercise because they don't understand the facts of exercise science. "We've been horribly misled and its time to put a stop to it," he says.
No need to sweat it out
Some experts agree that exercise alone will do little for the waistline, but they still advocate a combination of physical activity and diet. "I share some of the sense of [what Glynn is saying], but you can't send a signal that you don't need to exercise," says Dr Steve Hambleton, federal vice-president of the Australian Medical Association. "It is probably true to say that it is very tough to exercise your way out of being overweight. Anyone who has a pedometer is disappointed after they do the maths," he says.
"It's certainly a very important weight-loss mechanism to exercise, but it's a lot easier to lose weight if you eat the right food and don't eat the wrong food." Glynn also claims that overweight people are at greater risk of injury and are more likely to die younger if they exercise because they will wear out their bodies faster. But Dr Hambleton says that while overweight people may be at greater risk of injury from exercise, "the risk and benefit is weighted on the side of benefit".
Professor Stephen Colagiuri, professor of metabolic health at the Boden Institute of Obesity, Nutrition and Exercise at the University of Sydney, agrees that the weight loss from exercise alone is modest but says it remains an important component. "If you just set out to exercise without doing anything about your kilojoule intake, it's highly unlikely that you will lose weight," he says. Prevention is better than treatment and that includes watching what we eat, being more active and minimising the time we spend sitting. "It is genuinely difficult to lose weight and keep it off without doing something drastic like bariatric surgery [gastric banding surgery] if you've been overweight for a long time," Professor Colagiuri says.
Susan Anderson, national director of healthy weight at the Heart Foundation, says it's careless to suggest that exercise for weight loss is useless. "It's irresponsible because movement is fundamental to health and therefore necessary for an individual to achieve and maintain an ideal healthy weight," Anderson says."All overweight people, and adults who are starting or re-starting physical activity and exercise regimes, should consult their doctor before beginning an exercise routine and gradually increase the intensity and duration of their activity. There is abundant evidence that adopting a healthy eating pattern and being physically active can control weight."
Julie Gilbert, a spokeswoman for the Dietitians Association of Australia, says weight loss comes from a combination of diet and exercise. "We know that 70 per cent of weight loss comes from cutting your portion size down and 30 per cent comes from exercise," she says. "Exercise plays the biggest role, not so much in terms of weight loss, but in terms of helping people to maintain their weight."
Mixed messages
Gilbert says diet is the most important aspect of weight loss, but if someone is only losing a quarter to half a kilo a week while on a diet, she would look at their physical activity levels. "The best part about exercise when you're trying to lose weight is it makes you feel good and when you feel good, you often don't eat a lot of the treat junk foods." The recommended 30 minutes of exercise a day will have no impact on weight loss and those trying to slim down need to do between 60 to 90 minutes of physical activity a day, she says.
Professor Jonathan Shaw, associate director of health services at the Baker IDI Heart and Diabetes Institute, says he is concerned that Glynn's message could be misinterpreted to mean that all exercise is pointless. "Exercise certainly has health benefits even if it doesn't lead to weight loss," he says. "Starting to lose weight is usually really easy. Most people can get the first three or four kilos off without much effort. One of the reasons it's challenging to lose more is the body will often try and respond to weight loss by trying to conserve energy ... so you need to be pushing yourself to keep that weight off."
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