Why am I so healthy? (I'm obese)?

A couple of times, I've participated in research at universities, where they gather health-profiles, to compare to patients etc. Every time, they comment on how surprisingly healthy I am.

They've checked my fasting blood sugar (4mmol/L - normal is 3 to 6-ish), they did an Insulin Tolerance Test (where I was very sensitive to insulin, and my hormones were very potent at stablizing me = very low chance of diabetes), they checked my cholesterol (don't remember the number, but it was much better than what they would have expected for a lean person, even), blood pressure (109 / 70 - normal is 120/80), pulse at rest (55 - normal is 60-100. 40-60 is athletes. The person who took this insisted that I must be in very good shape, but I don't do anything), measured WHR (0.7 - Optimal is 0.7-0.79, and it is bad if it is more than 0.85), and a lot of other things: Most of it was better than average, and nothing was worse than average.

As I mentioned, I don't do any form of exercise, or take walks, or anything. I walk to the bus, I go up the stairs for classes, and I walk to get groceries, that's pretty much it. I don't struggle to do any of these things, but I wouldn't want to run after the bus or walk to the 3rd floor.

I eat alright, though too much obviously, compared to how little I do. I like veggies and healthy foods, fish is my preferred meat and I never eat fast food, but I probably eat more carbs (rice, bread etc) and a bit more sweets than ideal, and I also get drunk in weekends. I prioritize my sleep, and I don't smoke, so nothing too unusual there.

^So it's not like I live like a health nut at all: So how can I be healthier than average, despite having a BMI between 35.6 and 38.2? (my weight goes up and down a bit), and thus unhealthy by definition?

What would happen if I was lean and in good shape then? Would I live to be a 100? :b Would all these values change a lot (and in that case, would it go too far in the other end of the spectrum?), or are they pretty stable no matter the weight, and in that case, is it just impossible for me to be unhealthy? O.o

It all seems very contradictory to me!