Associations between bone mineral density, body composition and amenorrhoea in females with eating disorders: a systematic review and meta-analysis

Plain English summary Individuals with eating disorders (EDs) have an increased risk for developing osteoporosis and suffering fractures. To better understand this problem, we conducted a systematic review and meta-analysis comparing bone mineral density (BMD) of females with EDs with that of healthy people without an ED. We also tried to identify key factors linked with reduced bone mass in EDs. We included studies reporting BMD of individuals with anorexia nervosa (AN), bulimia nervosa (BN), binge-eating (BED) or other non-specified ED (OSFED), and of healthy controls. We found that people with AN had overall lower BMD than controls and also in the spine, hip, and femur. In people with BN, there was lower BMD overall and in the spine, but that must be only in those who previously had AN. In people with OSFED, BMD was lower in the spine. Having a low BMI, low fat mass, low lean mass and not having menstrual periods seem to negatively affect BMD. Therefore, this systematic review supports the idea that people with current or past AN, irrespective of their current ED diagnosis, should have their bone health assessed. For early identification of those most at risk, body composition measurements, current menstrual status, duration of amenorrhoea and presence or absence of a history of AN should be considered in clinical practice. Background Lower bone mineral density (BMD) increases the risk of osteoporosis in individuals with eating disorders (EDs), particularly women with anorexia nervosa (AN), making them susceptible to pain and fractures throughout adulthood. In AN, low weight, hypothalamic amenorrhoea, and longer illness duration are established risk factors for low BMD, and in people with other EDs a history of AN seems to be an important risk factor for low BMD. Purpose To conduct a systematic review and meta-analysis of BMD in individuals with EDs, including AN, bulimia nervosa (BN), binge-eating disorder (BED) and other specified feeding or eating disorders (OSFED) compared to healthy controls (HC). Methods Following PRISMA guidelines, electronic databases were reviewed and supplemented with a literature search until 2/2022 of publications measuring BMD (dual-energy X-ray absorptiometry or dual photon absorptiometry) in females with any current ED diagnosis and a HC group. Primary outcomes were spine, hip, femur and total body BMD. Explanatory variables were fat mass, lean mass and ED clinical characteristics (age, illness duration, body mass index (BMI), amenorrhoea occurrence and duration, and oral contraceptives use). Results Forty-three studies were identified (N = 4163 women, mean age 23.4 years, min: 14.0, max: 37.4). No study with individuals with BED met the inclusion criteria. BMD in individuals with AN (total body, spine, hip, and femur), with BN (total body and spine) and with OSFED (spine) was lower than in HC. Meta-regression analyses of women with any ED (AN, BN or OSFED) (N = 2058) showed low BMI, low fat mass, low lean mass and being amenorrhoeic significantly associated with lower total body and spine BMD. In AN, only low fat mass was significantly associated with low total body BMD. Conclusion Predictors of low BMD were low BMI, low fat mass, low lean mass and amenorrhoea, but not age or illness duration. In people with EDs, body composition measurement and menstrual status, in addition to BMI, are likely to provide a more accurate assessment of individual risk to low BMD and osteoporosis.