The aim of this study was to identify the dietary-intake correlates of food insecurity in UK adults. We recruited groups of low-income participants who were classified as food insecure (n = 196) or food secure (n = 198). Participants completed up to five 24h dietary recalls. There was no difference in total energy intake by food insecurity status (βFI = −0.06, 95% CI −0.25 to 0.13). Food insecure participants consumed a less diverse diet, as evidenced by fewer distinct foods per meal (βFI = −0.27, 95% CI −0.47 to −0.07), and had more variable time gaps between meals (βFI = 0.21, 95% CI 0.01 to 0.41). These associations corresponded closely to those found in a recent U.S. study using similar measures, suggesting that the dietary intake signature of food insecurity generalizes across populations. The findings suggest that the consequences of food insecurity for weight gain and health are not due to increased energy intake. We suggest that there may be important health and metabolic effects of temporal irregularity in dietary intake, which appears to be an important component of food insecurity.