Food insecurity would be affected by environmental impacts of the food system because insufficient food production yields to the number of consumers. This study aimed to develop a simulation model of greenhouses gas (GHGs) emission related to food consumption of Thais by population age group and simulate scenarios of changing food consumption with the altering outcomes on environment. Aging chains were made by age group of infants, children, adults and elderly and GHGs from food consumption were calculated. Population for each age group and their consumption were optimized to actual numbers. Simulations were set at 2006-2030. The overall emission was higher than that of Food-based Dietary Guidelines (FBDGs). The contribution was the highest from adults. The four scenarios were made by changing amount of food consumed. Reducing meat intake and substituted energy intake by vegetables has influenced to decrease of emission. Decreasing of beverages in children and adults provided the drastic change in decreasing GHGs. Additional increase of milk intake by elderly had affected to GHGs level in a few numbers. Food choices may ultimately result in impacts on the environment. It is therefore recommended that environmental friendly consumption practices should be encouraged for human well-being and food security.