Timing, frequency, and regularity as chrono-nutrition are emerging fields in nutritional epidemiology. The authors investigated the association of irregularity in energy intake, frequency, and overnight fasting with nutrient quality and health. Methods: Iranian adults who attended the health center of Tehran participated in this cross-sectional study. Dietary intake was derived from 3-day 24-h dietary recalls of 850 participants. Weight, height, and blood pressure of the participants were measured, and frequency, irregularity, and overnight fasting were recorded from 24-h dietary recall. Then, intra-class correlation coefficient (ICC) was used to obtain the consistency of time regarding three main meals. Following that, energy density was measured and nutrient density was calculated using the nutrient rich food (NRF 9.3) index. Obesity was defined as body mass index (BMI) >30 kg/m2, and blood pressure was measured. Results: The highest consistency regarding the time of meal was observed at breakfast. Frequency was positively related to the intake of fruit, energy, carbohydrate, and NRF 9.3 index (P<0.05). Overnight fasting was negatively associated with fruit, vegetable, grain, energy intake, and NRF 9.3 index (P<0.05). Moreover, irregularity in energy intake showed a negative and significant association with fruits, vegetables, and NRF9.3 (P<0.05). Frequency was significantly associated with weight and diastolic blood pressure (DBP) after adjustment with covariates (P<0.05) and overnight fasting was negatively related to body weight (P=0.009). Moreover, irregularity in energy intake showed a significant association with systolic blood pressure (SBP) (P=0.03). Conclusions: Frequency and regularity may have a potential positive association with dietary intake which is not associated with BMI. Nutrient density is higher among the participants with a higher number of eating occasions, more regular eaters, and shorter overnight fasting.