Associations between cardiorespiratory fitness and weight loss in patients with severe obesity undergoing an intensive lifestyle intervention program: retrospective cohort study

BACKGROUND: To assess the association between cardiorespiratory fitness (CRF) and weight changes in treatment seeking patients with severe obesity who underwent a 1-year intensive lifestyle intervention (ILI) program. METHODS: Retrospective cohort study conducted at a tertiary care outpatient rehabilitation center from November 1, 2013 through January 1, 2017. CRF was measured as maximal oxygen consumption during a maximal oxygen uptake (VO(2max)) test on a treadmill or bicycle at baseline and after 3 months. RESULTS: A total of 180 patients had a baseline mean (SD) BMI 41.1 (4.8) kg/m(2) and CRF of 79.4 (14.9) mL·kg(-0.75)·min(− 1). Patients with a baseline CRF above median achieved a greater 3-month and 1-year weight loss compared with patients with CRF below median; mean (95% CI) 2.5 kg (1.3, 3.8) and 4.0 kg (0.8, 7.2), respectively. In addition, patients with 3-month changes of CRF above median had 4.0 kg (0.9, 7.1) greater weight loss at 1-year follow-up than those below median. CONCLUSIONS: Among patients with severe obesity who underwent a 1-year ILI program, higher baseline CRF was associated with significantly larger weight loss after 3 months and 1 year. In addition, those with higher initial 3-month CRF changes had greater weight loss at 1 year. TRIAL REGISTRATION: Retrospectively registered in Regional Committees for Medical and Health Research Ethics (REC) south east September 22, 2016 (2016/1414) and clinicaltials.gov August 13, 2018 (identifier: NCT03593798). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12902-019-0394-z) contains supplementary material, which is available to authorized users.