Adults with obesity have atypical gait with poor balance leading to an increase in fall risk. After massive weight loss, their gait improves. However, we know little about changes in postural stability after massive weight loss. The present study aimed to examine how massive weight loss after Roux-en-Y bariatric surgery affected adjustments in center of pressure (COP) velocities during flat ground walking and obstacle crossing. Before and one-year post-bariatric surgery, nineteen female adults walked under four conditions: baseline walking on flat ground and obstacle crossing with three different obstacle heights for a total of 20 trials. COP data were obtained from raw pressure time series data extracted from a gait carpet. Massive weight loss increased anteroposterior COP velocities under the midfoot of both trailing and leading legs (ps<.01) and decreased mediolateral COP velocities under the forefoot of trailing leg (p < .05). Decreased BMI from pre- to post-surgery was correlated with an increase in anterior-posterior and decrease in medial-lateral COP velocities and with increased velocity (ps<.05). Massive weight loss not only improved gait but also facilitated effective balance control strategies. Examining how massive weight loss affects adjustments in COP velocity may help create ways to better understand why individuals with obesity have atypical gait with poor balance and how we can facilitate participation in physical activities.