Great lunch options from McDonald's, Starbucks, and 13 other popular fast-food chains to keep you energized all day

While we know that what you eat for lunch affects your productivity for the rest of the day, this doesn't mean you have to rule out convenience for the sake of healthy choices.

Plenty of chains offer meal options that are heavy on the protein and healthy fats and easy on the carbs and bad fats, which is just what you need to avoid the 3 p.m. slump, says Lisa DeFazio, a healthy-lifestyle expert and registered dietitian.

Take Chipotle: An oversized burrito is probably not the best thing for your productivity, but bowls and other less-carb-heavy options with lots of protein and healthy fats like avocado will give you just what you need to feed your brain without overdoing it, DeFazio says.

These healthier fast-food lunch options should keep you from passing out at your desk:

Nutritional content may vary and is based on company guides.