The patties are cooked right in front of you and it's claimed they use high quality meat, but Five Guys' classic cheeseburger is the unhealthiest in America. 

And McDonald's, frequently slammed for its salty, overly processed food, actually has one of the healthiest cheeseburgers. 

That's according to researchers who analyzed the nutritional value of cheeseburgers at 24 fast food chains in the US, comparing their calories, sugar, fat and sodium content.

Based on these metrics, each burger was given an 'unhealthiness score.' 

The classic cheeseburger from Five Guys was crowned the least healthy burger with an unhealthiness score of 50. 

This was mainly determined by looking at the burger's saturated fat, which raises cholesterol and can lead to heart disease. It 73 percent more saturated fat than any other cheeseburger on the list, and it was loaded with half a day's worth of calories. 

The Virginia-based chain also took first place for unhealthiest French fries, totaling 28 points, largely for the regular order's high calories and sodium. 

Meanwhile, McDonald's surprisingly tied with Burger King for the second-most healthy burger for having one-third of the calories and sodium of Five Guys' cheeseburger.

The two were just narrowly beat by Culver's Butterburger, which earned an unhealthiness score of 17 due to its low saturated fat and having just half the calories of Five Guys' pick.

The researchers wrote: 'Ultimately, healthy eating comes down to taking control of what you eat.

'That might mean avoiding fast food altogether, but it can be as simple as making an informed decision about which fast-food chains to visit and which of their products to choose.'

The researchers evaluated cheeseburgers, fries, chicken sandwiches, and nuggets from 24 US food chains and scored them based on the UK Department of Health's nutrient profiling method. 

This ranks foods by their nutrients related to chronic diseases, which included saturated fat, sugar, calories, and sodium. 

For example, saturated fat and sodium have consistently been linked to heart disease, obesity, and high cholesterol. 

Five Guys' cheeseburger was deemed the least healthy, with 55 grams of fat, 73 percent more than any other option on the list. 

Additionally, it has 1,050 milligrams of sodium, nearly half USDA's recommended daily limit of 2,300 milligrams. 

Loading up on sodium could lead to high blood pressure, which weakens blood vessels around the heart and other vital organs like the brain, leading to heart attack and stroke. 

It also adds up to 980 calories, half the daily recommended limit for most Americans. And that's without fries to go with it. 

However, the chain also offers a 'little' cheeseburger with 610 calories. 

Whataburger's Jalapeno and Cheese and Smash Burger's Classic Smash followed close behind, both scoring a 42 on the unhealthiness scale. Both picks had the highest scores for sodium, with 1,800 and 1,630 milligrams, respectively. 

Carl's Jr's Famous Star With Cheese and Sonic's cheeseburger rounded out the top five, scoring 37 and 36, respectively. 

Meanwhile, the Butterburger from Culver's was the healthiest burger, scoring 17. 

A single, which has one hamburger patty, has just 460 calories, less than half the Five Guys choice. It also has just 11 grams of saturated fat and 610 milligrams of sodium. 

And despite long being vilified for being unhealthy, McDonald's tied for Burger King for the second-healthiest cheeseburger. 

Scoring 18 points, one McDonald's cheeseburger has only 300 calories, one-third of Five Guys, and six grams of saturated fat. It also has 720 milligrams of sodium, roughly one-third of the recommended daily value. 

McDonald's also had the healthiest chicken sandwich and chicken nuggets, which scored 14 and 18, respectively. 

Burger King's option, meanwhile, has only 290 calories, six grams of saturated fat, and 780 milligrams of sodium.