To determine whether the strict rules of a very low calorie diet influence the frequency of dietary lapses, the magnitude of the abstinence violation effect, or the situational determinants of lapses, we compared the lapses reported by obese subjects with Type II diabetes who were randomly assigned to a balanced low calorie diet (LCD; N = 48) or to a very low calorie diet (VLCD; N = 45). Both self-monitoring diaries and periodic telephone interviews were used to assess dietary lapses. Telephone interview lapses were categorized as subjective or subjective with calorie violation, depending on whether the calories in the lapse day exceeded the goal by > 20%. Data from both diaries and phone interviews indicated that lapses were reported with equal frequency in the two diet conditions. However, the situational determinants of lapses differed; for subjects in the LCD group, emotion was more likely to be the primary trigger of subjective lapses and more subjective lapses occurred while in a negative mood. For VLCD subjects, food and cravings often served as the primary triggers of both subjective lapses and subjective lapses with calorie violation. Other situational determinants, most importantly, the degree of hunger, were similar in the two conditions. Following a lapse, VLCD subjects were more confident than LCD subjects about avoiding future lapses and continuing to lose weight. Thus, there was no evidence that the rigid rules of the VLCD increased the frequency of lapses or led to greater feelings of abstinence violation after the lapse.