I didn't write that. I wrote that in my own experience, most of the people who are overweight who try unsuccessfully to lose weight a) don't have as healthy a diet as they'd like to believe and b) don't exercise long enough and intensely enough if they work out at all.

What is a "healthy diet"? I don't believe there's a one-size-fits-all answer, but I mentioned processed foods because at the highest level, there is plenty of evidence that processed foods are problematic when consumed in the quantities they are being consumed in:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2897733/ http://news.yale.edu/2013/03/06/yale-researchers-identify-sa... http://www.biomedcentral.com/1741-7015/11/63 http://www.diabetes.org/news-research/research/access-diabet... http://jn.nutrition.org/content/139/10/1950 http://wholegrainscouncil.org/whole-grains-101/health-studie... http://www.sciencedaily.com/releases/2012/02/120210110038.ht...

Well this whole discussion, especially debunking citations with citations, pretty much is a big evidence in favour of the original thesis - we don't know for sure pretty much anything about nutrition.