CHICAGO &#8212 It wasn’t so long ago that the McDonald’s fast-food empire looked as stale as a burger left under a heat lamp too long.

Sales were decreasing, new products weren’t catching on and McDonald’s Corp. was vilified by consumer activists, nutritionists and others as Americans got fatter and fatter. Even its seemingly bulletproof stock staggered to barely $12 a share in 2003.

Now, thanks to a combination of improved menus, better marketing and deft management, business is cooking like never before.

The comeback may not be news to anyone who has queued up at a McDonald’s drive-through recently. But the fact that the sales resurgence not only continues to sizzle but has spread internationally is a surprise to experts.

“A couple of years ago everyone was down on them,” said Bob Goldin, an analyst at Chicago-based food consultancy Technomic Inc.. “Now it’s hard to find people who are really hard critics of the company.”

The latest evidence of the brand’s renewed popularity came last week when the company said August same-store sales rose 8.1 percent worldwide and exceeded the year-earlier total for a 53rd straight month. Recent product introductions – premium coffee, snack wraps and salads – all contributed to the domestic surge.

Even shareholder activists have gone quiet after having the company on the defensive over its lagging stock price. Its stock has soared to all-time highs above $55 since it announced its largest-ever dividend increase Sept. 13 and pledged to return $15 billion to $17 billion to shareholders through dividends and buybacks by the end of 2009.