In a 1990 study of several hundred people by University of Vermont professor Esther Rothblum, the heaviest were most likely to report they had been denied benefits including health insurance because of their size. Many said they had been fired or threatened with dismissal for weight reasons.

Women suffer the greatest unfairness, she said. "They don't have to weigh very much for employment discrimination to kick in."

Rothblum once showed a set of identical resumes to a group of students. Half stated that the fictitious female job seeker was 120 pounds. The other half put her weight at 180 pounds. She asked the students to rate the woman's professional competence and suggest her appropriate salary range.

The 180-pound woman scored dramatically lower. "The amazing thing about that experiment," Rothblum said, "is that, actually, 180 pounds is not that heavy. Imagine what larger people experience. I think fat people underestimate how much of their daily encounters are different because of their weight."

Legal protections for overweight workers who feel they were discriminated against are scant. State and local disability law varies widely when it comes to the overweight.

"It's a patchwork," said Sondra Solovay, an Oakland, Calif., attorney and author of the book, "Tipping the Scales of Justice: Fighting Weight-Based Discrimination" (Prometheus Books; $19).

The only places in America with laws explicitly barring size discrimination are Michigan; Washington, D.C.; San Francisco, and Santa Cruz, Calif. In the late 1990s Champaign-Urbana, Ill., and Madison, Wis., passed appearance discrimination laws that potentially could extend to cover weight-based cases.