Energy bioavailability can be influenced by food matrix factors and processing conditions or treatments. In this study, the effects of endogenous sweet potato amylase enzyme activation and slurry solids content of soy‐enriched orange‐fleshed sweet potato (OFSP) porridges on in vivo energy bioavailability (energy, weight gain, and feed efficiency ratio) and porridge acceptability were determined. Fifty‐six weanling albino rats were randomly assigned to two blocks each having eight groups of seven rats. The rats were housed in individual cages in a well‐ventilated animal house. The intervention block had rats fed on activated porridges (held at 75°C for 15 min), while rats in the control block were fed on nonactivated porridges (boiled at 90–95°C for 10 min). The rats were fed for 28 days on 50 ml of porridge per rat per day. The four groups per block were each fed on porridges with varying amounts of total solids content (10%, 15%, 20%, and 25%). Weight gain, energy bioavailability, and feed efficiency ratio were determined at the end of the feeding period. Consumer acceptability of activated and nonactivated porridges at 25% solids content was determined using a nontrained human panel ( n = 40). Activation of amylases did not significantly ( p > .05) affect the bioavailable energy, cumulative weight gain, and feed efficiency of the rats. Increasing slurry solids content of activated and nonactivated porridges significantly ( p < .05) increased feed efficiency ratio (−14.6 ± 11.7 to 102.3 ± 2.3), weight gain (−1.4 to 5.6 g ± 1.9 g), and bioavailable energy (702.8 ± 16.2 to 1242.8 ± 12.2 kcal). Activation of amylases reduced porridge viscosity but did not significantly influence the overall acceptability. This work demonstrates the opportunity of utilizing sweet potato amylases to facilitate the preparation of complementary porridges with appropriate viscosity and increased energy density.