They basically trap for null or empty values in the event that the user clicks the Search button without selecting valid options for both usage and configuration.
Perhaps selection for the caring professions, especially medicine, could be made less by good grades in chemistry and more by such considerations as sensitivity and sympathy.
Here's the reality. On a physiological level, your breakfast choices - or lack of them - can set off a cycle of cravings and blood sugar spikes that spells doom for weight control.