Why didn’t the examiner ask you about exercise or diet, but did ask about smoking? Well, actuarial tables exist to account for the effects of smoking, and a host of other conditions. There simply aren’t actuarial tables to account for self-reported exercise or dietary habits, so the examiner is not going to ask about those things. Such tables, especially for dietary habits, would be difficult-to-impossible to write with any degree of accuracy. Just using your BMI as a proxy for those things is easier to measure, accounted for in existing tables, and “good enough”.