PSMF - protein sparing modified fast. Essentially any plan that is low-enough in calories to produce good weight loss rates, while high enough in protein to protect against muscle loss during dieting.
There are a few lower sodium frozen meal options. Kashi and Healthy Request and some of the Lean Cuisine line aren't too bad.
Also, you don't have to make your dinners from scratch. There are a lot of ready-to-eat foods that fit into the calorie, fat, and protein requirements (such as canned tuna and lean meats).
If you use a calorie counting website, you can choose 140 to 300 calories of lean protein as your meal (so 140 to 300 calories of rotisserie chicken breast or any lean meat would count as your ready-to-eat meal, and you could then add your veggies).
Lean deli meats would work (though some are pretty salty, there are reduced sodium options at least for turkey and chicken).
A can of tuna and some low-fat mayo or dressing actually fits the guidelines for a "shake" so I will often use a can of tuna as my "shake".
Yogurt, cottage cheese, eggs, (well usually 1 egg with a couple of egg whites - makes a good egg salad)... there are a lot of foods that you can use (or tweak such as the eggs) to fit the guidelines.