Lynette Perrett, 55, of Stanhope Gardens, was one of five semi-finalists named in a national weight-loss competition in Sydney last Thursday.

Ms Perrett, who won the Best Health Improvement category, lost 56.2kilograms in 20 months.

She weighed 125.8kg when she joined Weight Watchers in 2007 and now weighs 69.6kg.

Other semi-finalists Sarah Herman, Helen Landas, Barbara Williams and Vicki Scrine are from other parts of NSW.

Ms Perrett decided to do something about her weight when she couldn't recognise her own reflection in a mirror at a shopping centre.

She joined Weight Watchers, meeting once a week, and worked out at her local gym three times a week.

``I've been overweight since school and was always the fat one in the family,'' she said.

``I hated having my photos taken and always felt the odd one out.

``The last straw was being told by my doctor if I didn't lose weight I'd need medication for my blood pressure and cholesterol because they were elevated.

``Now I stop and think before I eat, think about healthy choices, think of chocolate as a treat not an everyday food. I do more exercise if I know I'll be eating out with limited choices of food.''

A Weight Watchers spokeswoman said the five NSW and ACT semi-finalists lost a combined total of 190.7kg and transformed their lives and health. The state winner, to be judged by a panel next month, will spend a week in Sydney for a makeover, magazine photo shoot and judging for the national Weight Watchers Slimmer of the Year award.