Obtain a preliminary assessment of the feasibility and acceptability of delivering the sustained lost weight (SLW) intervention in a real-world clinical setting for patients who have completed a 21-week very low calorie diet (VLCD).

Hypothesis: Intervention will be feasible to implement as evidenced by the ability to recruit and retain participants and acceptable to participants as evidenced by self-report of satisfaction with the program and adoption of weight maintenance behaviors.

Secondary Aim: Obtain a preliminary assessment of the effectiveness of the sustained lost weight (SLW) intervention for patients who have completed 21 weeks of a very low calorie diet (VLCD).

Hypothesis: Greater than 75% of participants who receive this novel approach, where maintenance behaviors are individualized based on resting metabolic rate and a physical activity factor, will regain greater or equal to 10 kg. at week 52 follow-up.

Inclusion Criteria:

• Completed fast and transition period of the OPTIFAST® program
• Be able to participate fully in all aspects of the study
• Willing to refrain from participating in additional weight loss interventions for the duration of the study
• Willing to provide written informed consent.

Exclusion Criteria:

• Myocardial infarction within 6 months
• Unstable angina
• Stroke
• Chronic steroid use
• Active peptic ulcer disease
• Advanced cirrhosis
• Active hepatitis
• Advanced renal disease
• Active thrombophlebitis
• Recent skeletal fractures
• Use of lithium
• Pancreatitis
• Pregnancy
• Type 1 diabetes mellitus
• History of diabetic ketoacidosis
• Active bulimia nervosa
• Severe depression
• Psychosis
• Substance abuse