Public Health Nutrition

Assessment and methodology

BMI ≥ 50 kg/m2 is associated with a younger age of onset of overweight and a high prevalence of adverse metabolic profiles

Jean O’Connella1 c1, Phillip Kierana1, Kathleen Gormana1, Tomas Aherna1, Tom J Cawooda1a2 and Donal O’Sheaa1

a1 Obesity Research Group, St Columcille’s Hospital and St Vincent’s University Hospital, Elm Park, Dublin 4, Republic of Ireland

a2 Department of Endocrinology, Christchurch Hospital, Christchurch, New Zealand


Objective To study the demographic and clinical parameters of three different categories of obesity, with particular focus on a cohort of individuals with BMI ≥ 50 kg/m2, the fastest growing category of obesity.

Design Over 700 obese individuals were studied (186 with BMI = 30–39 kg/m2, 316 with BMI = 40–49 kg/m2 and 290 with BMI ≥ 50 kg/m2).

Results Median BMI was 51 kg/m2 for patients who reported onset of overweight before 15 years of age, 47 kg/m2 for patients who reported onset between 15 and 30 years, and 42 kg/m2 for patients who became overweight after 30 years of age. The BMI ≥ 50 kg/m2 group was notably younger than the group with BMI = 30–39 kg/m2 (44 (sd 11) years v. 50 (sd 15) years; P < 0·0001). Eighteen per cent of obese patients studied were considered metabolically healthy according to standard cut-off points for blood pressure, fasting glucose and lipid profiles. However, the proportion of metabolically healthy individuals was significantly higher in the BMI = 30–39 kg/m2 group than in the BMI = 40–49 kg/m2 and BMI ≥ 50 kg/m2 groups (31 % v. 17 % and 12 % respectively; P < 0·05 and P < 0·005). When compared with people of similar age in the general population, individuals with BMI ≥ 50 kg/m2 had lower rates of marriage (51 % v. 72 %) and a higher prevalence of unemployment (14 % v. 5 %).

Conclusions The current study suggests that the increasing prevalence of childhood obesity worldwide will lead to many more individuals achieving a higher BMI at a younger age. Furthermore, an earlier onset of overweight does not appear to prevent the adverse metabolic health outcomes associated with extreme obesity.

(Received June 26 2009)

(Accepted December 07 2009)

(Online publication January 26 2010)


c1 Corresponding author: Email