A 6-week longitudinal study with N = 126 overweight women participating in a weight-loss programme investigated the hypothesis that focusing on the process (dietary behaviours) rather than on the outcome of dieting (weight loss) is associated with more successful goal pursuit and achievement. As expected, process focus was related positively to subjective daily success in dieting as well as to actual weight loss, and negatively to deviations from the diet. In contrast, outcome focus had a negative impact on successful dieting: focusing on weight loss was marginally negatively related to actual weight loss and was associated with more disinhibition after lapses. Confirming hypotheses, self-regulation failure (i.e. deviations from the diet, disinhibition) was negatively related to daily affective well-being. Contrary to hypotheses, however, goal focus was not directly associated with affective well-being but only indirectly through self-regulation. Focusing on the process rather than on the outcome of dieting, then, might help achieving difficult health-related goals and support self-regulation but does not contribute directly to affective well-being.