The goal of this clinical trial is to prospectively assess the efficacy of the BLOOM program, a comprehensive weight loss dietary and lifestyle program, in a population of patients living with obesity and awaiting hip or knee surgery. The main questions it seeks to answer are:

1. Can the BLOOM program support these patients to lose up to 10% of their initial body weight?
2. Will patients continue to lose weight for the next six months after completing the program?
3. Does the BLOOM program help patients to improve their overall quality of life?

Study participants will undergo the BLOOM program, a virtual pre-operative weight management program that spans 24 weeks and is carefully supervised by medical professionals. They will be recruited at the LEAF Clinic after being referred by their primary care physician.

During the BLOOM program, they will meet with a physician (initially, then once monthly) and a dietitian (initially, and then biweekly as part of virtual group coaching). They will have access to LEAF's online learning portal. These are normal elements of the BLOOM program.

Furthermore, as part of their participation in the research study, participants will be asked to complete the following questionnaires: the Mediterranean dietary score, the Oxford Hip and Knee Questionnaire and the EQ-D5-5L quality of life assessment. They will complete these initially, and then at completion of the program and 3 and 6 months post-program. We will also collect their height and weight at these intervals.

Inclusion Criteria:

• To be eligible for the study, subjects must meet all the following criteria:

  1. Age ≥ 18 years old
  2. Body mass index (BMI) ≥ 35 kg/m2
  3. Have being identified as a potential orthopedic surgery candidate by the Total Joint Assessment Clinic (TJAC)
  4. Have a referral by their primary care practitioner
  5. Ready to participate actively in the program (i.e., readiness to change scale score ≥7)
  6. Acquisition of the required technology tools and skills to use the virtual platform (the BLOOM program will be conducted via virtual video conference)
  7. English comprehension at a level that allows for active participation in the program

Exclusion Criteria:

• Subjects who meet any of the following criteria are not eligible for the study:

  1. Active eating disorder
  2. Active substance use disorder
  3. Active smoking
  4. Currently or past enrollment in another weight loss program in the previous year prior to enrollment in the study
  5. Ongoing pregnancy or breastfeeding

There is currently no plan to share IPD with other researchers, nor are we seeking institutional ethical approval for such sharing.