Global food production faces significant challenges, acting as a primary driver of land use change, biodiversity loss, and greenhouse gas (GHG) emissions, while a significant part of the world's population still struggles with food security and nutrition. In response, the EAT-Lancet Commission has proposed a healthy and sustainable planetary diet aimed at reducing resource-intensive foods like meat, starchy vegetables, and eggs, while suggesting a 67% increase in global per capita unsaturated oil consumption (e.g., soybean, sunflower, rapeseed) and the maintenance of the current palm oil intake. Using a spatially explicit land allocation algorithm, we assess how future global food oil demand for the expected 9.2 billion people by 2050 might impact forests and other carbon-rich ecosystems, along with associated land use change GHG emissions. We also evaluate the potential consequences of substituting palm oil with other vegetable oils, noting their different health and environmental implications. Results show that the projected 74% rise in global vegetable oil production for food by 2050 would require 317 million hectares of land-a 68% increase compared to maintaining current consumption. This could escalate pressure on forests and threaten global food security, potentially causing 115-120 million hectares of deforestation and 1163-1210 Mt. CO