Tirzepatide is a dual agonist of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors with potent effects on body weight regulation, glucose homeostasis and metabolic health. However, its interaction with dietary and exercise interventions as well as its impact on obesity and hepatic metabolic pathways, particularly in females, remain unclear. Here, we tested whether tirzepatide, alone or combined with time-restricted feeding (TRF) or resistance training, modulates energy balance, strength performance, adipose tissue remodelling, insulin sensitivity and hepatic lipid accumulation in female mice. Female Swiss mice after 10 weeks of obesity induction were treated with tirzepatide, TRF or resistance training for 8 weeks. Tirzepatide was administered subcutaneously using a dose-escalation protocol. TRF consisted of a 12 h feeding window, and resistance training was performed as stair climbing on alternating days. Body weight, caloric intake and feed efficiency were monitored longitudinally. Glucose homeostasis was assessed by intraperitoneal glucose and insulin tolerance tests. Adipose depots, skeletal muscle and liver mass were quantified, and hepatic lipid accumulation was evaluated by histology and RT-qPCR of lipogenic metabolism genes. Tirzepatide reduced body weight gain and feed efficiency, consistent with a negative energy balance. When combined with TRF and resistance training, tirzepatide accelerated weight loss, and the addition of resistance training further enhanced this effect, bringing body weight close to control levels. These effects were associated with reduced adipose mass and adipocyte hypertrophy, indicating improved adipose tissue remodelling. Resistance training improved strength performance and increased skeletal muscle mass. Tirzepatide combined with TRF, with or without resistance training, improved glucose tolerance in female mice. All interventions reduced hepatic lipid accumulation. Collectively, tirzepatide, particularly in combination with TRF and resistance training, exerts enhanced metabolic benefits on obesity, insulin sensitivity and metabolic regulation in female mice. KEY POINTS: Tirzepatide combined with time-restricted feeding and resistance training produced greater reductions in body weight and adiposity in obese female mice. Combined interventions improved whole-body insulin sensitivity more effectively than isolated strategies. Resistance training preserved skeletal muscle mass during tirzepatide-induced weight loss. All interventions similarly reduced hepatic lipid accumulation and lipogenic gene expression. Tirzepatide-based therapies enhanced systemic metabolic health without additional hepatic benefits from combined interventions.
