I'm not. Came to LC six years ago after reading the chapter in Gary Taubes GC, BC on Cancer and Dementia,and there has been nothing but many more studies in those six years since linking obesity and cancer. https://www.ncbi.nlm.nih.gov/pubmed/27168354
Taubes has a similar chapter in his new book, The Case Against Sugar, starting with the 2003 CDC report that overweight men and woman have a 50-60% increased risk of many common cancers. So no, there are sizes that are unhealthy...maybe not at age 30 but in a lifetime.
http://www.obesity.org/resources/fa.../cancer-obesity