What specific risks are associated with ignoring low body weight, defined by a BMI under 18.5?

Weakened immune function, muscle wasting, and fragile bones

Maintaining a body weight significantly below the healthy range, indicated by a Body Mass Index below 18.5, poses serious physiological risks that extend beyond mere appearance. The body, lacking necessary reserves, begins to compromise essential systems. This can manifest as a weakened immune function, making the individual more susceptible to illness and infection because the body cannot adequately support immune cell production or response. Furthermore, the body starts breaking down its own structural components, leading to muscle wasting, which further lowers metabolism and strength. Perhaps most critically for long-term health, insufficient nutrition can compromise bone density, resulting in fragile bones that are more prone to fractures.