Hormonal

Resting metabolic rate (RMR) reduction following weight loss is driven primarily by the loss of adipose tissue mass and metabolic adaptations, rather than the loss of skeletal muscle mass.

You don't need to obsess over preserving every gram of muscle to stop your metabolism from slowing down. Research shows that losing fat mass itself, along with hormonal shifts (like lower leptin and thyroid hormones), is what actually drives your resting metabolic rate down after weight loss. This means metabolic adaptation is a natural response to losing fat, not just a failure to build muscle. To manage this, focus on sustainable, slower weight loss and personalized strategies that address these hormonal changes, rather than just trying to 'save' muscle.