Despite many Americans effort to cut out sodium from their diet, many restaurants are not making it easy to cut back.

An analysis of 136 meals put four meals at both Red Lobster and Olive Garden in the top 10, with food from Arby's and Chili's rounding out the list from the Center for Science in the Public Interest. 

The advocacy organization says some meals at popular chains such as Red Lobster, Chili's and Olive Garden contain up to 5,000 milligrams of sodium -- more than double what a healthy adult should be eating each day.

The good is that on average, these 17 restaurant chains have reduced the sodium in their meals by 6%. The bad is that a few chains increased the amount of salt on their menus.

"For far too long, the FDA (Food and Drug Administration) has relied on a voluntary, wait-and-see approach when it comes to reducing sodium in packaged and restaurant food," Michael Jacobson, the advocacy group's executive director, said in a statement.

"If chains like KFC, Jack in the Box and Red Lobster are actually raising sodium levels in some meals, FDA's current approach clearly isn't working."

However, there have been improvements. Subway showed the most dramatic improvements as it cut sodium in every one of the 10 meals that were analyzed. For example, in 2009 a Footlong Ham Sandwich with chips and a soda totaled 2,730 milligrams of sodium. In 2013, the same meal had 1,895 milligrams of sodium.

Burger King, McDonald's, Pizza Hut and Taco Bell also reduced the sodium in all of the meals that researchers analyzed.

CSPI noted that there are numerous chains not included in the study that have posted information showing they serve meals with a sodium content higher than anything included in its study.