If current weight gain rates are continued, normal-weight adults will constitute less than a third of the population by 2025, and the obesity prevalence will have increased by 65 per cent, according to Monash University research.

In findings published in Obesity, the research conducted by lead authors, Helen Walls and Dianna Magliano, followed the weight of a group of adult participants aged under 25 years of age in the year 2000.

The research found that in this population, approximately one-fifth of those with normal weight or overweight progressed to a higher weight category within five years.

Following these trends, only about 28 per cent of adults would be at a healthy weight in 2025 but nearly 34 per cent would be obese.

Dr Helen Walls, study leader and a research fellow at Monash University said that while the percentage of people who were overweight was expected to remain steady - about 38 per cent, over the 25 year period the numbers of obese people would increase dramatically.

"Many people in the overweight category will move into the obese category, however, they are being replaced by increasing numbers of people who are currently in the normal weight range," Dr Walls said.

"Fewer than 30 per cent of the youngest people in the study group currently in the healthy weight range will remain so by 2025," Dr Walls said.

Dr Walls said the surge in obesity could be prevented if the government implemented the recommendations of the National Preventative Health Taskforce, with a countrywide approach of tackling obesity.

"The evidence generally suggests that individual-based strategies aren't going to work," Dr Walls said.

"Educating people about good nutrition and the importance of physical activity isn't generally effective, and that is very intuitive for people who know how they can live more healthily but don't."

For more information contact Megan Gidley, Media and Communications + 61 3 9903 4843 or 0448 574 148.