Lifestyle interventions have had established efficacy for decades but they are costly and have poor scalability. Remotely-delivered lifestyle interventions have increased the potential for scale and systematic reviews have found that they are effective, especially those that include human coaching. Some remote lifestyle interventions are synchronous, such that they are delivered via videoconferencing or phone. Other remote lifestyle interventions are asynchronous, such that they are delivered via online platforms that allow for clinicians and patients to engage via text exchanges or via online groups where patients engage with a clinician and each other by posting messages and contributing to discussion threads. The advantage of asynchronous approaches are 24/7 accessibility which makes them conducive to "just in time" support, allowing patients to engage anytime they want to, as opposed to in scheduled blocks of time each week. Asynchronous, remote interventions may also be more scalable than synchronous remote interventions. We conducted a trial of two asynchronous, remote lifestyle interventions-one with a group of 94 participants and one with a group of 40 participants. Findings revealed similar weight loss and acceptability between conditions. We also found that the larger group was more sustainable, such that participants continued to engage in the group for longer when we turned the groups over to participants to lead themselves for a year after the intervention ended-a period we referred to as the peer-led maintenance phase. The next step in this research is to examine how an asynchronous, remote intervention compares to a synchronous, remote intervention, not only in short term weight loss, but also in sustainability, scalability, and weight loss maintenance. Now that we've established the feasibility of conducing large asynchronous, remote groups, in the proposed trial we will randomize participants to large groups (n=82) in both conditions, which will allow us to compare synchronous to asynchronous remote interventions that are scaled up to a level that we have established is acceptable for asynchronous remote interventions. The purpose of the proposed trial is to determine whether an asynchronous, remote lifestyle intervention is non-inferior to a synchronous, remote lifestyle intervention in weight loss at 6 and 12 months, but more scalable and sustainable, and thus producing greater weight loss maintenance at 18 and 24 months. Establishing evidence for asynchronous interventions is more important than ever given that telehealth reimbursement for behavioral health has recently expanded but is still limited to synchronous forms of remote care. Asynchronous interventions may be more convenient for some people and possibly more scalable but for this treatment model to reach its potential, evidence for efficacy is needed to inform reimbursement policy. We hypothesize that an asynchronous, remote lifestyle intervention will produce similar initial weight loss as a synchronous, remote version but will be less expensive, more sustainable, and generate greater collective efficacy, which will drive greater weight loss maintenance at 18 and 24 months.