The Low GI Diet has been the University's Professor of Human Nutrition, Jennie Brand-Miller, along with Joanna McMillan-Price who is researching her PhD at Sydney and dietician Kaye Foster-Powell. It is a follow-up to the series of books by Professor Brand-Miller, The New Glucose Revolution, which have sold more than two million copies worldwide over the last 8 years.

The book is based on choosing low GI carbohydrates, which are slowly digested and absorbed producing only gentle rises and falls in blood glucose and insulin levels. The diet also places an emphasis on regular exercise.

The Glycemic Index, on which the book is based, was developed by the University's Human Nutrition Unit and has since spawned a website, www.glycemicindex, and a trademarked food labelling program, the GI Symbol Program.

"I believe this is the most solid scientific platform on which any popular diet has ever been based," said Professor Brand-Miller at the launch of the book. "We do not describe it as a low-fat, low-carb or high protein diet. It is much more flexible than that and aims to act as a blueprint for healthy eating for the rest of your life."

The launch of the book coincided with the results of a new study by Joanna Macmillan-Price comparing the effects of four different diets on weight loss, body composition and cardiovascular risk.

"In the first month the participants in each diet performed more or less the same. After that the results separated showing weight loss on the low GI diet was more sustained," said Ms Macmillan-Price. "This is important because part of our hypothesis is that a low GI diet helps to prevent middle aged spread as well as immediate weight loss."

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Employment grade was divided into three categories: administrative (the seven highest paying grades), executive (including senior executive officers, higher executive officers, executive officers and other professional and technical staff receiving similar salaries), and clerical (including clerical and office support grades). Participants also answered questions regarding family history of diabetes, coronary risk factors (including smoking, alcohol consumption, exercise habits and diet), and psychosocial questions regarding work, social support, depression, and relationships.

The researchers found that over an average follow-up time of 10.5 years, 4 percent of the participants (242 men and 119 women) developed diabetes. Men working in lower employment grades had almost three times the risk of developing diabetes, and women had a 70 percent higher risk of developing diabetes than participants in higher employment grades. Participants whose body mass index (BMI) indicated overweight (BMI, 25.0-29.9) or obesity (BMI, 30 or greater) were at increased risk of diabetes. Among the psychosocial risk factors examined, only effort-reward imbalance was associated with diabetes, and only in men, who had a 70 percent greater chance of developing diabetes if they reported experiencing effort-reward imbalance.

"We have demonstrated that there is a social gradient in incidence of type 2 diabetes in middle-aged men and women in white-collar occupations," write the researchers. "In addition, we show that effort-reward imbalance is associated with incidence of type 2 diabetes in men only."

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