Malnutrition is a major concern in Madagascar. Eating a wide variety of nutritious food is necessary because Malagasy diets heavily rely on rice consumption. This study explored the barriers to dietary change towards diversification from the perspective of consumer behaviour. We analysed the impact of risk and time preferences on dietary diversity using economic experiments conducted with 539 rural lowland rice farmers in Central Highlands in Madagascar. The results showed that risk-averse or impatient individuals were more likely to have lower Household Dietary Diversity Score (HDDS), indicating poorer diet quality. Risk-averse people may not want to add different foods to meals as they perceive unfamiliar food as a ‘risk’; people who prefer immediate gratification may fail to invest in nutritious diets now to achieve better health in the future. Additionally, higher HDDS was observed among households with a female head who earned off-farm income and who had frequent market visits. These findings contribute to explaining the limited shift in nutritional transition in Madagascar and provide useful insights into nutritional policies promoting healthier food choices. Depending on the preferences, more focused support such as nutritional education, financial support, market development, and pre-commitment mechanisms could be provided to reward long-term nutritional benefits.