Dunkin Donuts' Glazed Doughnut Breakfast Sandwich, which debuted last week, packs bacon and a fried egg between two halves of a glazed donut. While this fatty treat may not be the healthiest way to start your day, at 360 calories, you could do worse. Here, a look at six other fast-food breakfast sandwiches that will have you unbuckling your belt:

1. Burger King's Enormous Omelet Sandwich
The "Home of the Whopper" unleashed this breakfast behemoth in 2005. The aptly named Enormous Omelet Sandwich features all the breakfast staples: a sausage patty, two omelet-style eggs, two slices of American cheese, and three strips of bacon served on a sesame bun. Clocking in at 730 calories, 47 grams of fat, and 1,860 milligrams of sodium per sandwich, it's no wonder Super Size Me director Morgan Spurlock told USA Today that Burger King should have offered customers "a $5-off coupon for [their] first angioplasty."

2. Hardee's Country Breakfast Burrito
The Hardee's chain, which has earned a reputation for selling high-calorie, meat-centric sandwiches and salads, started selling the Country Breakfast Burrito in 2007. This 920-calorie monster is made up of a tortilla stuffed with bacon, sausage, ham, cheese, hash browns, and eggs — all smothered in country gravy.

3. Carl's Jr.'s Breakfast Burger
This morning version of a hamburger features a patty layered with a fried egg, bacon, hash brown nuggets, cheese, and ketchup. At 810 calories with 42 grams of fat, it's no wonder Care2 recently put the Breakfast Burger at the top of its list of the scariest fast-food breakfasts.

4. Hardee's Double Sausage, Egg 'N' Cheese Biscuit
The creators of the Country Breakfast Burrito couldn't resist trying to top themselves in 2010 with the release of the Double Sausage, Egg 'N' Cheese Biscuit. The sandwich, which packs in 830 calories, 63 grams of fat, and a massive 2,100 milligrams of sodium, layers two sausage patties, two slices of cheese, and an omelet-style egg atop a country biscuit.

5. McDonald's Sausage, Egg and Cheese McGriddle
The Sausage, Egg and Cheese McGriddle combines the sweet and savory by placing a sausage patty, American cheese, and an omelet egg between two syrup-infused buns. A single sandwich will weigh you down with 550 calories and 31 grams of fat.

6. Subway's Footlong Mega Omelet Sandwich
This massive, 1,430-calorie breakfast beast features an assortment of meats, cheese, vegetables and eggs on a foot-long slice of bread. Its staggering 2,100 milligrams of sodium led Men's Health to name it the "Saltiest Breakfast Sandwich."