The problem started when Apple CEO Steve Jobs appeared last June to unveil the new generation of iPhone.

Dressed in a black sweater that billowed around a thinned-out frame, Jobs delivered a tech message that was immediately drowned out by questions about his health. An Apple spokesperson explained away Jobs' gaunt appearance, saying he was getting over a "common bug."

The unlikely explanation, and the fact that Jobs survived a 2004 bout with pancreatic cancer, caused investor panic. Apple stock fell more than 6 per cent in two days.

Rumours of heart attacks and Jobs' imminent death continued to batter the stock up until the year's end. Yesterday, Jobs revealed in an open letter the "very personal" news that he is suffering from a hormonal imbalance that robs his body of nutrients. With treatment, he hopes to regain his lost weight by the end of the spring.

After the letter's release, Apple stock jumped more than 4 per cent.

While Jobs' position as Apple's prime mover makes his appearance and health legitimate concerns for investors, this raises a thorny workplace issue: When is my weight other people's business?

The short answer is never.

"I would never approach a person and say, `You've gained a lot of weight, or lost a lot of weight,'" said Ruth Clark, senior vice-president of human resources at Hill & Knowlton Canada, recoiling from the idea. "That's very personal."

Instead, Clark said, companies have begun steering their employees en masse toward healthier lifestyles through programs like subsidized gym memberships.

"We treat our people as the adults they are," Clark said.

"If someone is off sick a lot, you're going to talk to them about that, but you'd never start off with `I noticed you lost some weight.'"

But people do notice. And that could change the way some co-workers are treated, for good or ill.

Beginning in 2005, Toronto city councillor Shelley Carroll shed "almost 100 pounds" in just over a year. She's kept the weight off and can't help noticing small changes in how she's treated.

"There really is no getting around the fact that sizeism exists, and it exists in professional life," Carroll said. "I still have people who feel they have to comment that they think it's an amazing achievement that you can keep (the weight) off. I have to wonder if I'm having a conversation with someone who wouldn't have bothered before."

Oprah Winfrey enjoyed the same sort of popularity bump when she thinned down to a size-10 jean 20 years ago. In the intervening decades, Winfrey's yo-yoing weight has become her defining personal narrative. Yesterday, she relaunched her TV show with a series entitled "Oprah's Best Life Week."

It's not clear how much of Winfrey's nearly $3 billion fortune rests on her weight battle, but it is clearly part of her appeal. However, if you're not Oprah, gaining a few pounds can cost you. Literally.

Professor John Cawley of Cornell University has studied the effect of weight gain on workers' wages.

"Heavier women tend to earn less. For men, it's much less consistent. In some cases, heavier men tend to earn more," Cawley said, describing the so-called "portly banker" effect.

"For guys, it can be a status symbol, showing that you're so successful you don't have to care about your appearance. For women, it's pretty consistently a negative relationship."

Cawley's research shows that for each 7.2 pounds a woman gains, she will earn 1 per cent less than a female colleague whose weight has not changed.

Loading... Loading... Loading... Loading... Loading... Loading...

According to Cawley, the effect is cumulative: gain another seven pounds, lose another percentage point of wages. The U.S.-based study showed the effect is more pronounced for white women than for black or Latino women.

So is the opposite true? Will losing weight equal a higher wage?

"The data tends not to be good enough (to say)," Cawley said. "And another issue is, what is it that led you to lose the weight? Some people are doing very unhealthy things to lose weight, which creates its own problems."

Read more about: