Airlines don't exactly serve gourmet food, but when hunger strikes almost anything will do. The question is, how healthy is that meal you are about to eat out of desperation?

Diet Detective has the answer.

The 2019-2020 edition of its Airline Food Study has just been released and top U.S. airlines have been ranked according to the nutritional value of the food they serve.

This year, additional criteria was used in the overall health score. Factors like total levels of sodium and calories were all taken into account.

Based on the results, here are nine airlines that serve the least healthy food:

9. JetBlue Airways

• Overall health score: 2.9/5.0
• Average overall calories: 295
• Average overall sodium: 547 mg

"The best thing about JetBlue is that it posts all its nutritional information on its website; however, as of this study the information is not up-to-date," wrote Diet Detective. "JetBlue has a few reasonably healthy meals on their EatUp Cafe menu; however, they are not offered on flights under 3 hours."

8. Delta Air Lines

• Overall health score: 2.9/5.0
• Average overall calories: 424
• Average overall sodium: 780 mg

Diet Detective noted that "full nutrition information should be accessible for improved transparency" with Delta.

7. United Airlines

• Overall health score: 2.7/5.0
• Average overall calories: 320
• Average overall sodium: 464 mg

Although United is improving in terms of its in-flight meals, working against the airline is that "there is no nutritional information on its website, no ingredients list, and United is still lagging behind other airlines on the environmental front," according to Diet Detective.

6. American Airlines

• Overall health score: 2.7/5.0
• Average overall calories: 481
• Average overall sodium: 678 mg

Diet Detective noted that, given the airline's size, "it should have healthier menu options and provide online menus with full nutritional info and ingredients."

5. Frontier Airlines

• Overall health score: 2.0/5.0
• Average overall calories: 289
• Average overall sodium: 367 mg

"The average calories in their in-flight offerings decreased for each category this year, but there is still room for improvement as to what those offerings could be," wrote Diet Detective.

4. Allegiant Air

• Overall health score: 1.9/5
• Average overall calories: 325
• Average overall sodium: 362mg

Allegiant has made an effort to provide food that is lower in calories, but Diet Detective noted that "it would be wonderful if the airline added a few more nutritious food items to the menu, perhaps an apple or a salad shaker."

3. Spirit Airlines

• Overall health score: 1.9/5
• Average overall calories: 360
• Average overall sodium: 450mg

"Spirit's in-flight offerings were hard to find on the airline's website. No nutritional information is provided for the food offered, and, overall, there are not many (if any) healthy options," Diet Detective commented.

2. Hawaiian Airlines

• Overall health score: 1.9/5
• Average overall calories: 556
• Average overall sodium: 755mg

"There are a lot of high-calorie and high-sodium options, and many of the snacks will not be satiating," wrote Diet Detective.

1. Southwest Airlines

• Overall health score: 1.7/5
• Average overall calories: N/A
• Average overall sodium (individual snacks): 135mg

"For one of the top carriers, Southwest does not offer much variety or nutritional value," Diet Detective stated. "Southwest needs to add some healthy snacks."

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