How is a negative energy balance defined?

A negative energy balance is defined as a state where energy expenditure exceeds energy intake. This means that the body is burning more calories than it is consuming through food and beverages. As a result, the body must utilize stored energy, typically from fat reserves, to meet its energy needs. This is the fundamental principle behind weight loss, as a consistent negative energy balance will lead to a decrease in body mass over time.

In this context, options referring to energy intake exceeding expenditure or resulting in equal levels do not describe a negative energy balance, while maintaining energy levels constant does not create a deficit or surplus, further highlighting that option C accurately captures the essence of a negative energy balance.