Final answer:
The relationship between BMI and mortality is often illustrated using a graph with a J-shaped or U-shaped curve, indicating that both very high and very low BMIs increase mortality risk, with normal weight being safest.
Step-by-step explanation:
When discussing the relationship between BMI (Body Mass Index) and mortality, studies typically illustrate this with a graph that has a J-shaped curve or U-shaped curve. The shape of the graph shows that both very high and very low BMIs are associated with an increased risk of dying. This indicates that a BMI in the middle range, corresponding to a "Normal weight", is associated with a lower risk of mortality.
It's important to note that while BMI is a common measure for assessing body fat, it does not account for the distribution of fat. For example, having a higher proportion of abdominal fat, a trait more common in men ("apple-shaped"), is associated with higher health risks compared to fat distributed around the hips ("pear-shaped"), which is more common in women and is associated with fewer health risks. Consequently, health assessments sometimes also include measurements of waist-to-hip ratio.