A recent study suggested that discrimination against overweight people - particularly women - is as common as racial discrimination. The study compared self-reported weight discrimination against experiences of discrimination based on race and gender among a nationally representative sample of adults aged 25 - to 74-years-old. The study also found "that women are twice as likely as men to report weight discrimination and that weight discrimination in the workplace and interpersonal mistreatment due to obesity is common."
RAND cites this as one of many distinctions between it and smoking - a previous public-health crisis that the US has managed to curtail. RAND writes, "Moreover, while smoking had been fashionable for decades, the same certainly cannot be said for obesity, to which there in fact has long been a stigma attached."
IFTF observes that weight discrimination could be compounded by the fact that obesity is more prevalent among lower income groups and historically marginalized populations, and it could emerge as a new discrimination frontier. This also opens some questions about whether obesity could be legally protected or obesity discrimination recognized in public policy, as implied by one of the lead authors. Chances seem unlikely, but weight bias is likely to receive more attention as consciousness of obesity increases.
RAND, Nov 2010, page 3-4: http://newsletters.clearsignals.org/RAND_Nov2010.pdf#page=3 
“Weight Bias is as Prevalent as Racial Discrimination, Study Suggests”, Science Daily, 28 March 2008, accessed 10/29/10 at: http://www.sciencedaily.com/releases/2008/03/080327172129.htm; 
See also: Puhl, Rebecca M., and Chelsea A. Heuer, “The Stigma of Obesity: A Review and Update”, Obesity, 2009. Accessed 10/29/10 at: http://www.yaleruddcenter.org/resources/upload/docs/what/bias/WeightBias...