The food we eat has a critical impact on human and planetary health. Food systems are responsible for approximately a third of total global greenhouse gas emissions (GHGEs). This review summarises studies that have measured dietary GHGEs and assessed their associations with various demographic variables. Most studies report dietary emissions at the individual level, but some studies use households as the unit of analysis. Studies investigating individuals estimate dietary intakes using 24-hour dietary recalls, food frequency questionnaires, diet history interviews, food diaries or other dietary records. Studies investigating households rely on food purchasing data and expenditure surveys. The majority of studies estimate dietary GHGEs using process-based life cycle assessments. It is difficult to directly compare emissions estimates between studies at either the individual or household-level due to methodological differences. In general, there are mixed findings with regards to the relationships between various demographic variables and dietary emissions, although older adults generally had higher dietary GHGEs than younger adults, and men typically had higher dietary GHGEs than women, even when standardizing for total energy intake. This review may be useful in informing and targeting policies and interventions to reduce GHGEs of dietary intake.