Costs of obesity, obesity-related complications, and weight loss in the United States: A systematic literature review.

Background: One hundred million American adults are living with obesity; 75% also have obesity-related complications. Related medical spending exceeds $261 billion dollars. A contemporary synthesis of evidence on the average, per person cost for people living with obesity (PwO) and the impact of obesity-related complications in the United States is lacking.

Objective: To summarize estimates of direct medical costs among PwO by obesity severity and presence of obesity-related complications and to characterize the impact of weight loss on direct medical cost savings.

Methods: A systematic literature review was implemented in MEDLINE/EMBASE on February 21, 2023, identifying observational studies and economic models published since 2012 reporting on direct medical costs among US PwO. Identified studies were screened; outcomes including all-cause and obesity-specific direct medical costs were extracted. Direct medical costs data were summarized overall, by obesity severity (class I, II, or III), and by the presence of obesity-related complications. Impact on cost savings with weight loss was also summarized. Where possible, comparisons with normal weight cohorts, obesity-related complications subgroups, and treated and untreated groups were explored.

Results: From 9,725 records identified, 32 studies (6.0%) were deemed eligible, all reporting all-cause, direct medical cost estimates. For mean costs per person per year (PPPY) by obesity severity (n = 15 studies), findings relative to a normal weight cohort (n = 11 studies) indicated total costs among PwO ranged from 1.1-fold (class I) to 3.3-fold (class III) higher. For costs by the presence of obesity-related complications (n = 7 studies; relative to an "obesity-only" group) costs were up to 5-fold greater among PwO with both type 2 diabetes and hypertension. Substantial savings were associated with 5% weight loss over 1 year (n = 5 studies). When costs among PwO using obesity medications (OMs) were compared with those among eligible nonusers (n = 3 studies), in 1 study OM users incurred lower costs than nonusers after 2 years. When mean costs among adults undergoing weight loss surgery were compared with nonsurgery controls (n = 5 studies), there was no associated reduction in cumulative total costs across the study periods.

Conclusions: Evidence from this review indicates that direct medical costs among PwO increase with increasing obesity severity and development of obesity-related complications. Although cost savings were observed with 5% weight loss, uncertainty surrounding cost savings accounting for the cost of more recently approved interventions remains. Furthermore, current evidence is lacking, and longitudinal studies considering a wider range and overlap of obesity-related complications are needed to help document and quantify the current direct cost burden of obesity.