There is increasing concern that patients gain considerable weight in the year prior to treatment and that outcomes may not reflect true treatment losses. To date, we know little about the accuracy of self-reported weight change prior to treatment. To investigate weight gain, and accuracy of self-reported recent weight history, Veterans (n = 126) reported their current weight and one-year weight history prior to entering treatment. These weights were compared to electronic medical record weights. Patients gained an average of 2.03 kg (4.5 lbs) in the year prior to treatment. Self-report and objective weight assessments showed high concurrent validity at the group level. However, standard deviations for the absolute difference scores revealed high individual variability in historical reporting, suggesting that weight loss seeking patients are inaccurate reporters of recent weight. Our findings have implications for the emerging area of pre-treatment weight gain research and processes for clinical care.