This study compared the lifestyle patterns, dietary patterns, and health care practices of Korean middle-aged people by household type, and ultimately analyzed their relationship with different risk factors for the prevalence and severity of metabolic syndrome. We analyzed the data from 4,755 subjects who were from 40 to 64 years old, and gathered our sample from participants of the Korea National Health and Nutrition Examination Survey from 2013 to 2015. Our results showed that single-person households had lower economic income levels, lower subjective health statuses, and higher levels of food instability than households with two or more individuals. The incidence of metabolic syndrome was 1.64 times higher in single-person households than in households with two or more individuals. After adjusting for potential confounding factors (sex, age, education, household income, smoking status, health status, and dietary factors), single-person households showed 1.75 times higher hypertriglyceridemia ORs than non-single-person households. In the conclusion of our study, we suggest that middle-aged people in single-person households may be at greater risk for metabolic syndrome and hypertriglyceridemia.