Bone Characteristics and Their Determinants in Adolescents and Young Adults with Early-Onset Severe Obesity

Abstract

Childhood obesity is associated with compromised bone health. We studied bone characteristics and their determinants in obese young adults. The study included 68 subjects with early-onset severe obesity and 73 normal-weight controls. Data on physical activity (PA), diet and smoking were collected. Bone characteristics were measured using peripheral QCT. The obese and control subjects were similar in age (mean 19.6 ± 2.6 years) and height but BMIs differed (39.7 and 22.6 kg/m(2)). A clustering of unhealthy lifestyles was marked: Obese subjects reported less supervised PA in childhood, adolescence and currently (p < 0.03) and were more likely to smoke (p = 0.005), and had a lower healthy eating index (HEI) (p = 0.007) but similar alcohol consumption compared with controls. In obese women, all crude bone characteristics were higher than in controls; in men, the differences were smaller. Associations of lifestyle factors with bone characteristics were tested using partial correlations. Independently of BMI, supervised PA in adolescence and alcohol consumption were related positively to bone characteristics in both groups. HEI associated positively with bone characteristics only in controls, while smoking was a positive determinant of bone characteristics only in obese subjects. The multivariate model showed that the contribution of lifestyle factors to bone characteristics was minimal compared with BMI. Early-onset obesity is accompanied by poor dietary quality, sedentary lifestyle, and more frequent smoking, but the overall contribution of these lifestyle factors to bone strength is limited. Bone strength is more likely to be compromised in men and in unloaded bone sites in subjects with early-onset severe obesity. The impact of obesity-related endocrine changes on bone characteristics need to be evaluated in future studies.

Metabolic milieu associates with impaired skeletal characteristics in obesity

“…Written informed consent was obtained from all study participants and in case of minors, the consent was obtained from their legal guardians as well. Inclusion criteria for the obese subjects were: i) weight-for-height ratio exceeding 60% before age 7 years, according to Finnish growth standards (comparable to BMI > 97 th percentile for age), ii) referral because of severe obesity to Children's Hospital, Helsinki University Hospital, during childhood, iii) residence in the capital region of Helsinki at age 7 years, and iv) aged between 15 and 25 years at the time of the study, as described earlier [10]. We identified a total of 366 patients fulfilling the inclusion criteria in the hospital's patient register and 68 (19%) of them consented to participate in the study.…”

“…Anthropometry including height (cm), weight (kg), and waist (WC; cm) and hip circumferences (cm) was collected during the study visit and BMI (kg/m 2 ) calculated, as described previously [10]. The health and diseases of the subjects, and their use of medicines were self-reported and collected with a questionnaire [10].…”

“…Similar association may be true for skeletal complications. Abnormal metabolic milieu may affect bone mineral accrual and bone size [9,10]. In fact, Lucas et al [11] demonstrated that high hs-CRP concentrations in overweight girls led to decreased BMD by 17 years of age.…”

Testicular Function and Bone in Young Men with Severe Childhood-Onset Obesity

“…BMI was calculated as weight divided by square height (kg/m 2 ). Lifestyle factors including smoking, alcohol use and current total physical activity, and use of medications were evaluated with questionnaires as described previously [22]. Less than 10 min of total physical activity per day was considered a threshold for a sedentary lifestyle.…”

“…We previously observed that in subjects with severe childhood-onset obesity bone strength is more likely to be compromised in men than in women [22]. This prompted us to evaluate testicular function and related skeletal features in males with severe childhood-onset obesity.…”