I feel like the description field could be described better

The contents of the column are irrelevant.

"Description" is the language - Ruby, SQL, Python etc., not "which items the events happened on" - that's the "created at" field

The "which events happened on" part clearly referred to the created_at field, so I'm not sure what you mean. Anyway, the description has been improved.

If you make the change you propose, your code will never return "Obese" and there will be a gap between bmi's.