Plateau

Eat more and incorporate weight lifting into your daily routine.

It's hard to answer these kinds of posts without more details. How long has it been since you last saw a drop on the scale? A plateau is something like 6-8 weeks without a drop on the scale and with no changes to your routine (since diet & exercise changes tend to come with some water weight retention - which can screw with the scale). If it's only been a few weeks, then it's possible that it's just a natural stall and will go away on its own.

Other than that, the most common problems we see come from underestimating calories eaten and overestimating calories burned.

Opening your diary might help to get you more specific advice if you're comfortable doing so.

You're logging everything you eat? Including condiments, cooking oils, veggies, cheat days, etc? Are you using a food scale, measuring cups, or eyeballing your portion sizes? Most people can be off in their estimates by several hundred calories when they eyeball portions. Measuring cups are better, but a food scale is going to be the most accurate.

http://www.myfitnesspal.com/topics/show/1234699-logging-accurately-step-by-step-guide
http://www.myfitnesspal.com/topics/show/1290491-how-and-why-to-use-a-digital-food-scale

And make sure that you've calculated your calorie goals appropriately. Remember that these are just estimates. You may need to play around a little to find what works best for you.

http://www.myfitnesspal.com/topics/show/1080242-a-guide-to-get-you-started-on-your-path-to-sexypants
http://www.myfitnesspal.com/topics/show/819055-setting-your-calorie-and-macro-targets

If you're exercising and eating back your earned exercise calories, be sure that you're using accurate estimates of your burn. MFP and gym machines have a tendency to overestimate certain activities, which can cause you to eat back more calories than you need to. Even a heart rate monitor isn't 100% accurate. If you're eating those extra earned calories it might be a good idea to eat only 50-75% of those.

And there's something to be said for the fact that some people just burn fewer calories than the generic equations predict. If that's the case for you, you may need to adjust your calories a little lower until you start losing again.

You've got to switch it up every so often. If you've hit a plateau, it's a big indicator you need to do this.
Your body adapts to whatever's thrown at it. It's just a survival/evolutionary thing we are designed to do.
For most of us its anywhere between 2-4 weeks. I like to switch every 3 weeks.
What do I do? I switch my lifting programs. 10-12 reps to strength which is 3-6 reps.
For nutrition, I've been on a ketogenic diet for the past 6 weeks. I've had to lower my calories for the past 2 weeks.

Eating more is actually good advice. As you consume less calories, your basic metabolic rate will drop causing you to burn less calories (in turn causes your progress to slow)
What you need to do after 3 weeks or so is eat more to bring your BMR back UP but at the same time, do more cardio to help bring your metabolism up quicker. After another week or two, lower your calories anywhere from 10-20% but no more than 25%!!! You will be back on track!