The purpose of this trial is to determine the most cost effective programme for overweight and obese individuals to maintain weight loss over a 2 year period.

Although short term weight loss is often achievable in overweight individuals, long term maintenance is generally poor. The researchers urgently need new information regarding the most cost effective programme(s) for maintenance of weight loss. This study will recruit 200 women and compare two approaches for providing support: one with intensive health professional support, the other peer group support facilitated by a research nurse with frequent 'weigh- ins'. The researchers will also compare two different diets one a high carbohydrate, high fibre, low glycaemic index diet versus one relatively high in monounsaturated fat and protein and low in glycaemic load.

Inclusion Criteria:

• Female participants
• Aged 25 to 70
• Those who have intentionally lost more than or equal to 5% of initial body weight in the previous 6 months will be recruited
• Objective evidence that volunteers were overweight or obese and have lost weight will be obtained from doctors records

Exclusion Criteria:

• Presence of major illness including cancers
• Established cardiovascular disease or stroke
• Diabetes
• Gestational diabetes
• Renal disease
• Malabsorption disorders
• Thyroid disorders
• Major psychiatric disorders
• Taking weight loss medication or medications known to cause weight gain
• Planning a pregnancy in the next 2 years
• Those who do not intend to be in the area for the next 2 years