Recent reports have highlighted the potential anti-obesity effects of epicatechin (EC) in regulating metabolism. Most studies have primarily used rodent models housed at standard temperatures (ST) 22°C ± 2°C. However, these mice may experience chronic cold exposure at ST, which can influence energy metabolism. Housing mice at thermoneutrality (TN) 28°C ± 2°C could provide a more accurate representation of human temperature conditions. Additionally, many studies focus solely on male animals, overlooking the significance of considering sex differences in the investigation of physiological and metabolic dysregulation. In our trial, we used both male and female C57Bl/6 mice, including lean and obese individuals. The mice were treated with either 12 mg or 20 mg of EC/kg of body weight (administered by gavage) over 12 weeks, five days a week, and were housed at either ST or TN. Contrary to previous reports, we found no anti-obesity effects from EC in either male or female mice at both doses. The mice exhibited similar weight gain, adipose tissue sizes, biochemical profiles, and liver fat accumulation when compared to obese, untreated animals. Furthermore, obese male mice supplemented with 20 mg of EC and housed at TN showed increased subcutaneous white adipose tissue (scWAT) weight and worsened glucose tolerance compared to their non-EC-treated counterparts. In conclusion, epicatechin administered by gavage did not improve obesity, liver steatosis, or insulin resistance in either male or female obese mice housed at ST or TN. This suggests that the route of administration and the EC dosage could influence its anti-obesity effects.
