To go back to the issue of being obese and healthy, I thought I might chime in since I have a somewhat unique PoV. My SO is a researcher in the field of obesity. While I'd really really REALLY like to say that one could be 400lb and healthy, that's just not what the science indicates. That's the general consensus here, so I won't dwell on it.
However, there are a lot of things you can do to help manage risks. Life without risk is boring, who cares if you live to 90. The key is to find that quality of life that you enjoy most and offers the best longevity returns. For example, organisms under stress (not stress like work related problems, but stress like extreme temperatures, insufficient water, calorie restriction, etc) tend to actually live longer: but who wants to live longer if they have to be miserable to do so?
If getting your SO to gain weight is part of what you two decide is an acceptable lifestyle choice, there are things you can do to help guide you. The first is to start seeing an MD/PhD, instead of just a regular MD. You will get better care, and they are more likely to be up on the "bleeding edge" knowledge. The second is to get your genes test, and if you can manage it, the genes of everyone in your families. This can be done fairly cheaply through companies like 23 and Me or DeCodeMe. Then, take those results to a genetic counselor to interpret them. And read up on health research as much as you can. Abstracts to all journal articles funded by the government (which is most of them) have to be posted to pubmed, and full articles of a lot of stuff are posted to pubmedcentral. Anyone can access those and get research straight form the source. Don't be too discouraged at how unreadable it all is: it takes researchers themselves years to learn how to read articles quick, and there is always a steep learning curve when one moves to a new field.
So yes, being obese is bad, but being ignorant is worse. Find those who can help guide you, and build your own knowledge base, and you'll decrease your health risks at every weight.
