The tendency to approach food faster than to avoid it (i.e., approach bias) is thought to facilitate food intake, particularly foods that conflict with one's dietary goals. However, this relationship has been difficult to demonstrate, which ties into an ongoing debate about whether such cognitive-behavioral biases represent stable traits or fluctuating states. We thus investigated the temporal fluctuations of food approach bias (1), its within-participant association with food craving (2) and intake (3), and the role of top-down control in this bias-intake association (4). The 76 participants completed an impulsivity questionnaire and performed a smartphone-based approach-avoidance task on nine days. Every day, they also reported their daily craving, intake, and dietary intentions for 12 personalized foods they wanted to eat less or more often over the study period. Approach bias varied considerably within individuals (1), and correlated in unexpected ways with food craving (2) and intake (3); this association of approach bias with intake was moderated by inter-individual differences (rather than day-to-day fluctuations) in dietary intentions and impulsivity (4). Results emphasize the need to re-conceptualize approach bias as comprising both state and trait components, and indicate that the more trait-like aspects of top-down control gate the relationship of approach bias with intake. The large day-to-day variation in approach bias may explain why single-session bias measures often do not predict distal outcomes like body weight. Furthermore, our results suggest that interventions targeting approach bias may be most effective for certain timepoints (high-risk situations) and individuals (those with weak dietary intentions).