18.5: 18

While the absolute risk is low compared to a BMI of 15, being at the lower end of the scale does carry potential downsides:

When body weight is low, caloric intake often follows suit. Individuals in the range may unknowingly consume insufficient micronutrients—especially iron (anemia risk), vitamin D, calcium, and B12. 18 18.5

Studies on distal radial epiphyseal fusion (wrist bone growth) indicate that complete fusion—a sign of reaching biological maturity—often occurs around 18.0 to 18.5 years of age. While the absolute risk is low compared to

If you walk into an office supply store or a vintage furniture shop, you will encounter the "18 to 18.5" rule in seating design. This range is the gold standard for chair seat height. 18 18.5