: The association of dietary patterns and resting metabolic rate is still unclear. : To study the relationship between the major dietary patterns, resting metabolic rate, and adiposity measures in Iranian adults. : This is a cross-sectional study of 270 adults aged between 18-45 years old who lived in Tehran. Dietary intakes were achieved using food frequency questionnaire. Resting metabolic rate was measured using indirect calorimetry. Anthropometric measures were recorded using body composition analyzer. : Three major dietary patterns were identified by factor analysis labeled as healthy pattern (vegetables, fruits, and fruits juices, legumes, poultry, nuts, fish, egg, low fat dairy product, olive, and olive oil), mixed pattern (non-refined cereals, vegetables, vegetable oils, mayonnaise, high fat dairy product and, pickles), Western pattern (refined cereals, red or processed meat, soft drinks, sweets and desserts, Tea and coffee, salty snacks and French fries). After adjusting for covariates higher score of the Western dietary pattern was associated with lower resting metabolic rate ( = 0.023). There was significant decreasing difference in means for fat free mass across tertiles of mixed pattern when the first tertile was compared to the third tertile ( = 0.046). Higher adherence to healthy pattern was associated with lower body weight ( = 0.034), body mass index ( = 0.021), and higher resting metabolic rate ( = 0.033). : Higher adherence to the Western dietary pattern was associated with a lower amount of resting metabolic rate. Also higher adherence to the healthy dietary pattern was associated with higher resting metabolic rate and lower body weight and body mass index. Further studies are required to examine the causal relationship between dietary patterns and resting metabolic rate.