The addition of resistant starch (RS) to a food lowers its energy density but its impact on appetite, food intake (FI), and body composition is not well understood. This study explores the effect of RS from high‐amylose cornstarch on FI, body composition, mineral‐absorption, and inflammatory markers when tested simultaneously in control (C) and moderately increased fat and sugar (HFHS) diets. Four groups of weanling rats are fed C, C + RS, HFHS, or HFHS + RS diets and their FI and body weight (BW) are recorded. After four weeks blood serum, abdominal fat, total gut weight, cecal content, and feces are collected and analyzed. FI increases (p < 0.000) in C + RS (440 ± 29 g) versus C (396 ± 40 g) while it decreases (p = 0.001) in HFHS + RS (419 ± 44 g) versus HFHS (481 ± 35 g). Both BW and abdominal fat decrease significantly in HFHS + RS (212 ± 39 g) versus HFHS (247 ± 28 g) (p = 0.032) and (7 ± 2.27 g) versus (10 ± 2.41 g) (p < 0.000), respectively but remains unchanged in C + RS versus C. Percent calcium absorption selectively increases in HFHS + RS (p <0.000) versus HFHS. In conclusion, RS effectively reduces FI, weight gain, abdominal fat‐mass, and enhanced mineral absorption differentially when added to standard or a moderately HFHS diet of growing rats.