NEW YORK (FORTUNE) - Imagine Ronald McDonald munching on soybeans or teaching yoga.

It's not as far-fetched as it sounds. The latest addition to McDonald's (Research) menu is an Asian salad made of orange-glazed chicken, snow peas, red peppers, mandarin oranges, almonds and green soybeans known as edamame. People who buy the salad as part of a "Go Active! Happy Meal" for adults are given one of four 15-minute exercise DVDS, including one that teaches yoga.

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The Asian salad and workout DVDs are fresh ingredients in a ongoing makeover at McDonald's that is intended to accomplish two things, one of which people at the company like to talk about and one of which they don't.

First of all, various salads, chicken sandwiches, sliced apples and yogurt parfaits have been added to the McDonald's menu to give more options to customers, particularly health-conscious women. Mothers who bring their children to Mickey D's used to complain that there was nothing on the menu that they wanted to eat.

"This is all about providing choice, be it salads or new premium chicken sandwiches or fruit," says Carol Koepke, senior director of U.S. marketing for McDonald's.

Second, McDonald's wants to get out in front of escalating social concern about obesity. To that end, the company agreed earlier this year to provide customers with nutrition information on its packaging. It has also been promoting "balanced, active lifestyles" - the idea being that the best way to stay trim is to burn as many calories as you take in.

Two years ago, as part of that effort, McDonald's gave out about 16 million plastic pedometers to promote walking for fitness. The DVDs are also an easy way for people to get active.

All of this delivers the message that obesity is not caused by "junk food," two words you'll never hear spoken at company headquarters in Oak Brook, Illionois. "We're proud of all of our food," a spokesman told me.

Still, McDonald's has to be concerned about its reputation, in the wake of the independent movie "Supersize Me" and the best-selling book "Fast Food Nation," which has just been adapted into a children's book and will be fictionalized for a movie coming out this fall.

Whatever the back story, McDonald's new attention to health concerns appears to be paying off, for the company's bottom line if not Americans' waistlines. Same-store sales in the U.S. have grown for an impressive 36 consecutive months. The company's share price is up by more than 30 percent in the past two years, outpacing the S&P500.

Of course, McDonald's still sells truckloads of burgers and fries. What's more, the company has made a slew of changes, unrelated to health issues, since its sales slumped in 2002.

It introduced a $1 value menu, modernized stores, made it easier for customers to use debit or credit cards and won praise for its "I'm Lovin' It" marketing campaign.

But McDonald's decision to play a role in helping its customers take better care of themselves has made a difference as well. Women are looking for ways to exercise without the bother of joining a health club, Koepke says, and they are paying more attention to what they feed their families. "Beef consumption is down and chicken is up," she says.

As it happens, McDonald's both reflects and drives that trend; it has 21 menu items with chicken as a primary ingredient, and nine with beef.

The idea of healthy McDonalds food is not entirely new - McDonald's has served salads since the late 1980s. But clearly something's changed - perhaps a willingness on the part of some McDonald's consumers to live healthier lives.

Remember the McLean burger, a low-fat burger introduced by McDonald's back in 1991? It never caught on. Nor did Salad Shakers, in part because people didn't want to eat salad from a cup.

By contrast, today's premium salads and chicken sandwiches are selling well, according to the company. Although it won't release specific sales figures, McDonald's says it sold 80 million pounds of spring mix for its premium salads and 54 million pounds of apples last year.

Of course, the company sells even more fatty, heart-clogging hamburgers and French fries, many packaged with plastic toys and aimed at children. Critics also note that some of the salads, when ordered with crispy chicken and slathered with dressing, do not exactly qualify as slimming.

Meanwhile, America's obesity epidemic is getting worse. A recent CDC study reports that 19 percent of children ages 6 to 11 are overweight.

But how much can we ask one company to do about a big social problem? (No pun intended.) By offering healthy choices, providing nutritional data and encouraging customers to get active, McDonald's is stepping up. It's no more the cause of the obesity epidemic than is Ben & Jerry's or Starbucks' Frappuccinos.