"It's not just about the burger. You're going to get something else to drink with that," said Ayoob. "Ask yourself if it's really that much of a bargain, or ask if this is a 'grabber.'"
Ayoob explained that many big chains often make more money on drinks and other simple side 'grabbers' than on the main meal.
"This is not something that's unique to fast food restaurants," he said. "Even at a fancy French restaurant, a look of gloom and doom comes over the waiter's face when you don't order a bottle of wine."
Not everything is gloom and doom for your diet while eating out. Nutrition and obesity researchers have noticed in recent years that fast food restaurants are leaning more and more toward healthy options.
Wendy's Mandarin orange cup, just a cup of orange segments, water and sugar, is one such example.
But the 80 calories that come in the $1 Mandarin orange cup make it one of the pricier choices per calorie on the menu.
"Most places have at least some foods that are likely to be better," said Brownell. "You see salads in places more often and you see places with salad wraps."
Brownell said not only are convenience restaurants adopting healthier choices, but healthier restaurants are popping up alongside the traditional fast restaurant locations.
"It's more common now to be healthy food outlets in the highway rest areas and in the food courts in malls," said Brownell. "It's not easy [to eat out healthy] but it's getting easier."
Common knowledge says breakfast is the most important meal of the day, but take a look at the calorie count on many chains' breakfast menus and breakfast can easily turn into the entire meal for the day.
The big steak omelette at IHOP, for example, racks up 1,490 calories, just 500 calories shy of a full day's recommendation.
Less calorie-dense but more economical is the Wendy's grand burrito combo, offered in New York for $4 and 1,330 calories with coffee. That morning meal comes to 332 calories per dollar.
Still, the grand burrito combo doesn't compare to the 510 calorie double cheeseburger at Burger King.
While some obesity experts argue it's the responsibility of the individual to eat right, others say, since restaurants could make it easier to eat healthy, they should.
"People are struggling financially right now. They [restaurants] know the tagline of affordability and cheap right now is a big seller," said Martin Binks, director of behavioral health research and an assistant professor at Duke University Medical Center in Durham, N.C.
"Making incredibly unhealthy food look even more financially viable in this economy is targeting the poor, in poor health," said Binks. "It would be nice if they took their healthiest options and make them more affordable."