Regarding the fat/heart disease hypothesis, you may find this site will provide you with some food for thought: www.thincs.org

The more I read and research, the more I'm convinced that the fat/heart disease hypothesis theory has more holes in it than swiss cheese and the "evidence" behind it is shaky indeed. Add to that the fact that I've been following low carb for going on 3 years now; I had a Thallium stress test last year (after being on low carb for almost 2 years). Result? I may be a little out of shape, but my cardiac arteries are clear as can be.
Ultimately, we have to do what we all think is best for us, but do yourself a favor and actually read some of the articles on the site that I provided a link to. As a diabetic, I should be more frigtened of developing heart disease than the average person because statistically, I'm at much higher risk than the average person and yet on low carb, my cardiac profile has done nothing but improve.
I'm still curious how long that neighbor of yours was on Atkins before this occurred?