Dietary supplement with a mixture of fish oil and krill oil has sex-dependent effects on obese mice gut microbiota

•Fish oil (FO) and krill oil (KO) treatments alleviate diet-induced obesity in mice.•FO and KO treatments show better anti-obesity effects in male mice.•FO and KO treatments lead to diversified gut microbiota modulation in mice.•The effects of FO and KO treatments on gut microbiota modulation are sex-dependent.