Moderate exercise won't help most people avoid becoming overweight or obese-or to keep weight off once they've lost it.

Australia's National Health and Medical Research Council mentioned the obvious, that a high-calorie, high-fat Western diet combined with decreasing levels of physical activity has put more people at risk of health ailments. But experts now recommend 60 to 90 minutes of moderate-intensity activity per day for formerly obese people.

"In the current environment of abundant availability, promotion and consumption of energy-dense food, it is now internationally recommended that 45 to 60 minutes of moderate-intensity daily physical activity is the minimum required... without reduction in current energy intake," the Australian government reported.

However, experts temper their recommendations to avoid discouraging people from giving up entirely. Dr. Amanda Lee, chairperson of the health organization's dietary guidelines committee, said she wouldn't want to discourage anyone with time for only 30 minutes or so of exercise per day.

"At this stage the national activity guidelines still recommend 30 minutes of moderate activity a day," she said. "Even then, not even 50 percent of the population is managing that, so I would be reluctant to tell everyone that they now need to find an hour."

Lee said Westerners must make either substantial dietary changes or significantly increase levels of physical activity.

"There's no denying we have a huge problem with what's called energy balance. Simply speaking we are eating way too much poor-quality, energy-dense food for the amount of daily exercise we're getting," Lee says. "The reality is if finding the extra time in your day to burn off that energy through exercise is just not possible, then it's important you eat less food and of better quality."

Presently, 14 million Australians fall into the overweight or obese category, according to Monash University there. If current trends continued, nearly 80 percent of Australians would fall into the overweight or obese category by 2025, including one of three children.

However alarming that might sound, Australia doesn't even make the top-ten list for worldwide obesity rates, according to the U.S. Central Intelligence Agency. On that list, the U.S. territory American Samoa ranks number one, with the United States placing sixth. While five of those most obese countries are in Oceania and another four in the Middle East, Western Europe and Australia are rapidly catching up, researchers said.

As people in the developed world become increasingly sedentary with Western-style diets high in fat and calories, health experts acknowledge the impracticality of devoting 60 to 90 minutes per day to exercise.

The National Women's Health Network in Washington, DC, recommends "incidental exercise" for people striving to stay healthy. Rather than spending time at the gym, physicians and others recommend walking to the corner, carrying your own groceries, and taking the stairs rather than the elevator, according to Dr. Adriane Fugh-Berman, an associate professor at Georgetown University affiliated with the group.

"The only exercise one friend of mine gets is climbing stairs to his office, which is nine flights up," Fugh-Berman said. "He does that two or three times a day, and it seems to keep him in shape."