Final answer:
Starvation mode slows the body's metabolic rate to conserve energy during times of reduced caloric intake, making dieting more challenging.
Step-by-step explanation:
The bodily mechanism that may sabotage efforts to diet by slowing the body's metabolic rate is D) Starvation mode.
Starvation mode is a defense mechanism of the body that activates during prolonged fasting or severe caloric restriction. It reduces the metabolic rate as part of an adaptive response to conserve energy when the body perceives it is in a state of scarcity.
When facing reduced caloric intake, the body prefers to decrease its basal metabolic rate (BMR) rather than deplete its fat stores. This intentional decrease in metabolism can make weight loss more challenging and cause dieters to feel colder and less energetic. In contrast, actions like increasing muscle mass, engaging in regular exercise, and getting adequate sleep can help maintain or even raise the metabolic rate.