We highlight the causal effect of energy poverty on health in France. After collecting original data from 5000 individuals, we first statistically study the correlations between different pathologies and different aspects of energy poverty. Then, using econometric models, we quantify the causal effect of energy poverty on physical health and mental health scores, and also on the risk of occurrence of certain pathologies. Our data show a significant difference in health status between energy-poor individuals and energy-sufficient individuals. Results confirm that falling into energy poverty significantly degrades health scores. Being in energy poverty reduces the World Health Organization’s (WHO) physical health score by 8.14 points. The negative and significant effect on the mental health indicator is 3.78 points. When individuals are in a situation of energy poverty, their self-assessed health scores are on average 3.37 points lower than individuals who are not energy insecure. In addition, individuals living in dwellings with poor roof insulation, humidity, or mold suffer more frequently from chronic disease or psychological distress. Finally, it appears that reducing energy poverty by 1% would save about EUR 476 million. Regarding mental disorders, this could rise to EUR 10.6 million.