What can extreme negative energy balance lead to aside from unfavorable body composition?

Extreme negative energy balance refers to a situation where the body is expending significantly more energy than it is consuming, often leading to weight loss. While some may seek this as a strategy to reduce body fat, it can have concerning physiological repercussions beyond just body composition.

Impaired reproductive function is a well-documented consequence of extreme negative energy balance. This occurs because the body recognizes a state of energy scarcity, often triggering hormonal changes that can disrupt the normal menstrual cycle in women and reduce testosterone levels in men. In women, this may result in amenorrhea (the absence of menstruation), which can affect fertility. In men, low energy availability can lead to diminished libido and infertility.

In contrast, enhanced cognitive function, improved athletic performance, and increased endurance capacity are not typically associated with extreme negative energy balance. In fact, cognitive function may decline due to insufficient energy and nutrients necessary for optimal brain health, while athletic performance and endurance capacity often suffer due to fatigue, muscle loss, and lack of adequate recovery caused by inadequate caloric intake. Thus, impaired reproductive function stands out as a clear and pertinent risk of extreme negative energy balance.