Does exercise really work?

You have heard it for years: to lose weight, hit the gym. But while physical activity is crucial for good health, it does not always melt off the weight - in fact, it can add some. That was the blurb on a recent cover story in Time magazine.

Time writer John Cloud stated his case: "Yes, it's entirely possible that those of us who regularly go to the gym would weigh even more if we exercised less. But like many other people, I get hungry after I exercise, so I often eat more on the days I work out than on the days I don't. Could exercise actually be keeping me from losing weight?"

"In general, for weight loss, exercise is pretty useless," Eric Ravussin, chair in diabetes and metabolism at Louisiana State University and a prominent exercise researcher, said in the Time article.

The basic problem is that while it is true that exercise burns calories and that you must burn calories to lose weight, exercise has another effect: it can stimulate hunger.

That causes us to eat more, which in turn can negate the weight-loss benefits we just accrued. Exercise, in other words, is not necessarily helping us lose weight. It may even be making it harder, Mr Cloud wrote.

So what is fact and what is fiction? Dr Hamish Osborne, a senior lecturer in sport and exercise medicine at the University of Otago, puts his side of the story...

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Is exercise really an effective means for weight loss? That was the important health question Time magazine raised in a cover story recently.

The article claimed exercise is not an effective health tool, particularly as it pertains to weight loss.

This is despite overwhelming evidence from the majority of the scientific literature that physical activity is not only an important component of effective weight loss, but a major contributor to good health.

A vast amount of research has proven exercise, when combined with a healthy diet, results in both weight loss and maintenance of a healthy weight.

The American College of Sports Medicine released an updated, evidence-based scientific report in early 2009 that proves these points.

Further, there is little evidence to the claim that exercising produces hunger so uncontrollable that it leads to weight gain.

If it were true you would just have to look around your local gym or jogging track to find a lot of overweight people.

In fact, research has proved just the opposite: overweight and obese women didn't eat any more food after 40 minutes of exercise than they normally would when sedentary.

Exercise does require effort, and it does require self-control.

But when these are combined to form a healthy lifestyle, the rewards are beyond substantial.

Economically, expenditures are reduced and people lead more enjoyable, more energetic and happier lives.

It has been estimated that obesity accounts for about $303 million in health-care costs per year in New Zealand.

This could be halved if New Zealanders met guidelines of 30 minutes' brisk walking daily.

Obesity is a major risk factor to good health.

Regular exercise is a key factor in reducing this risk to one's health, independent of weight.

Regular exercise halves the risk to one's health of being obese.

This is partially through the effect of exercise on lowering blood pressure and cholesterol, risk of diabetes and heart disease.

This effect occurs regardless of whether there is weight loss, and obviously an even greater effect occurs if there is a reduction in weight.

Even for the non-overweight, exercise provides benefits that no single pill or prescription ever could.

It treats and prevents numerous chronic conditions, such as heart disease, high blood pressure, type II diabetes, lower back pain, arthritis, and even depression.

And it is important to note that the risk of sudden death while exercising is less than the risk of death by accident while driving somewhere to exercise.

Maori and some Polynesian groups have diabetes rates three times as high as New Zealanders of European descent.

The complication rates of diabetes are up to 10 times higher for Maori at least in part due to high rates of obesity.

Exercise has been shown in these groups to be highly effective at treating and preventing both diabetes and obesity.

An article earlier this year in the British Journal of Sports Medicine showed just how dangerous it is to not exercise.

This study followed over 2000 sedentary men for more than 10 years.

Those who took up regular exercise (30 minutes of brisk walking daily) gained as much health benefit as those who did not take up regular exercise but gave up smoking.

Put simply, inactivity is as dangerous as smoking! The New Zealand Government, through Sparc initiatives, encourages regular physical exercise.

Initiatives such as Push Play, Green Prescription, He Oranga Poutama and No Exceptions provide pathways of support across different populations in New Zealand.

Exercise is a health tool we all need, regardless of our weight, and the public should be taking its importance seriously.

Further, advice about weight loss should come courtesy of a qualified health or fitness professional, instead of irresponsible articles that fail to show the full realm of scientific facts surrounding the issue.

- Dr Hamish Osborne is a senior lecturer in sport and exercise medicine at the University of Otago.