The COVID-19 pandemic has impacted the mental health of people worldwide. An increase in perceived stress can lead to unhealthy behaviors such as increased food consumption. The aim of this study was to find the level of perceived stress and its relationship with increased food consumption during the “third wave” of the COVID-19 pandemic in Spain. This was a cross-sectional study that employed anonline self-reported frequency of consumption questionnaire and the Perceived Stress Scale-10. A total of 637 subjects participated and 83.6% of respondents had moderate or high stress—more prevalent in the female and young respondents. Moreover, 36.1% of respondents reported that they had increased the frequency of consumption of some foods, mainly nuts, snacks, and jellybeans, along with coffee, tea, cocoa, and soft drinks. Eating between meals was more pronounced in those with high stress (65.1%) than in those with moderate stress (40.4%) and low stress (20.2%). Furthermore, the respondents with high stress reported greater weight gain. Thus, the results show that the level of perceived stress during the ‘third wave’ of this pandemic increased food consumption.