<p>Selective Forwarding Attacks (SFAs) occur when compromised nodes intentionally discard specific packets, posing a serious threat to energy and power efficiency in 6LoWPANs. The self-healing mechanisms within RPL are insufficient in detecting and mitigating SFAs, leaving the network vulnerable to security threats. This research aims to comprehensively analyse the impact of SFAs on CPU, LPM, Tx, and Rx consumption in MRHOF and OF0 objective function scenarios within 6LoWPAN, focusing on the effect of attacker nodes on energy and power consumption. Our findings indicate that CPU consumption in MRHOF exhibits mixed effects, whereas in OF0, it shows widespread increases. Similarly, LPM consumption in MRHOF fluctuates due to the mixed impacts, while in OF0, it presents varying patterns. Tx and Rx consumption in MRHOF experience more pronounced increases, whereas OF0 demonstrates a combination of substantial decreases and anomalies. Additionally, both energy and power consumption rise significantly in the presence of attacker nodes, with OF0 exhibiting a higher percentage increase compared to MRHOF. These variations highlight the critical influence of the selected objective function (MRHOF and OF0) on resource utilisation and security resilience. The study underscores the need for targeted mitigation strategies to optimise energy efficiency and strengthen network security, especially in adversarial environments.</p>