Dietary factors (e.g. feeding treats and table scraps) can predispose to obesity in dogs, but it is not known whether they also influence success of weight loss. Therefore, the aim of the present study was to determine which pre-weight-loss factors were associated with outcome of their weight management regimen in dogs. Information from ninety-five dogs attending the Royal Canin Weight Management Clinic, University of Liverpool (Wirral, UK), was reviewed. The effect of different food types (e.g. dry, wet and home-prepared), feeding practices (e.g. method of portion size calculation and number of meals per day) and use of treats was assessed on outcome measures of the weight management regimen. Before weight loss, most owners (sixty-three out of ninety-five, 66 %) fed twice daily, used complete dry food (seventy-two out of ninety-five, 76 %) and calculated portion size either by measuring cup (thirty-six out of ninety-five, 38 %) or by visual estimation (thirty-seven out of ninety-five, 39 %). Feeding treats was common and included purchased treats (forty-one out of ninety-five, 43 %), table scraps (twenty-four out of ninety-five, 25 %), pet food (eighty-three out of ninety-five, 87 %) and human food (eighty-one out of ninety-five, 85 %). The majority of feeding practices did not influence any outcome measure for the weight-loss period (P>0·05 for all). However, metabolisable energy intake during weight loss was significantly higher in dogs fed dry food (P = 0·047) and lower in dogs fed purchased snacks before weight loss (P = 0·036). Thus, most pre-weight-loss factors have limited effect on outcomes of weight loss. The significance of the associations identified between feeding of dried food and purchased treats, and weight-loss energy intake, requires further study.