In Iran’s economy, monetary policies can alter household food consumption patterns and reduce nutritional quality through increases in liquidity and inflation—an issue that has received limited empirical attention at the food-group level. This study analyzes the effects of monetary policies on the caloric shares of 14 major food groups in urban and rural areas, examining the relationship between liquidity, food prices, and real income. Panel data from 30 Iranian provinces over 2004–2022 were used, and a seemingly unrelated regression (SUR) model was applied to estimate the food-group equations simultaneously while accounting for cross-sectional error correlations. Results indicate that increases in liquidity, both directly and through interactions with prices and real income, significantly affect caloric shares. In urban areas, higher liquidity reduced the share of calories from nutrient-rich groups such as dairy and meats, while increasing the share from cheaper, energy-dense items like cereals, oils, and sweets. In rural areas, monetary policies, through declining real income and relative price changes, increased the caloric share of grains and legumes while reducing consumption of protein and dairy groups. Overall, the findings suggest that monetary policies can shift food baskets toward lower-quality calories even without reducing total caloric intake, thereby threatening hidden food security. The results underscore the importance of considering nutritional impacts in policy design and implementing targeted food interventions tailored to urban and rural contexts.