Diet is a lifestyle factor that contributes to the risk of overweight/obesity and cardiovascular disease. The objective of this study was to examine the hypothesis that a Mediterranean-type dietary pattern (M) is associated with healthy body weights in a large suburban municipality in Ontario. A random cross-sectional sample of 759 adults, 18 to 65 years of age, participated in a telephone survey, which included questions on the frequency of consumption of 60 food categories. Principal components analysis showed that food categories aggregated into six low-order dietary factors and two high-order dietary patterns. The M pattern reflected higher consumption of fruits and vegetables, olive oil and garlic, and fish and shellfish. The non-M pattern reflected high fat/nutrient poor, meats and poultry, and foods high in added sugars. The M-score was inversely related to body mass index (BMI) (p = 0.027). After adjustment for gender, education, income and marital status, a higher M-score predicted a lower BMI in the 40 to 49 year age group. Heart health promotion strategies aimed at preventing adult obesity should emphasize components of a Mediterranean-type diet pattern.