Consumer Reports tested doughnuts from four chains—Dunkin' Donuts, Krispy Kreme, Starbucks, and Tim Hortons—across the U.S. These stores all claim they've removed trans fat from their doughnuts. So we had a lab analyze the ever-popular glazed and Boston Cream varieties for trans fat, saturated fat, and total fat.

What we found: All were legally trans-fat-free (meaning they contained less than 0.5 gram per doughnut) but technically not, since each sample had traces of trans fat present. Under U.S. Food and Drug Administration regulations, manufacturers can declare their product trans-fat-free if it contains less than 0.5 gram of trans fat per serving.

Among the samples tested, the Starbucks glazed doughnut was the heftiest at 4.2 ounces, and had the highest total fat content (22.9 grams) and saturated fat (11.4 grams). Tim Hortons' honey dip doughnut came in with the lowest numbers for total fat (5.7 grams) and saturated fat (2.5 grams).

The American Heart Association recommends that no more that 1 percent of your total daily calories be from trans fat. So for a 2,000 calorie diet, that means a total of about 2 grams of trans fat per day. There's no kidding yourself that even legally trans-fat-free doughnuts are healthy. Based on our tests, all four chains are living up to their trans-fat claims, but these doughnuts—at between 200 and almost 500 calories a shot (based on manufacturer information), plus up to 23 grams of total fat (and 11 grams of saturated fat)—should be treated as an occasional indulgence only.