Eat less vs cardio

Take care of your knees. Losing weight is more about food than the exercise.

As long as you are doing 150 minutes/week of exercise, anything after that it is in most cases better to just eat less, unless you are training for something. And of course its all relative, you still should be eating around your suggested BMR rate at least and have a healthy no more than -2lbs/wk loss rate in general, -2 to -.5lb/wk depending on how much overweight you are.

General principles: Moderate cardio is good for you. Short bursts of high intensity cardio is good for you. Eating moderately is good for you. Eating VERY little is not terribly good for you. Regardless of the number of calories you are eating, you have minimum micronutrition requirements (e.g. so many milligrams of potassium, calcium, magnesium) and macronutrient requirements (e.g. so many grams of protein, fiber) and the more you reduce your calories, the harder it is to meet those minimum goals. So achieving a calorie deficit GENERALLY speaking is going to be healthiest if at least part of that deficit is from burning exercise calories and the rest of it from a moderate eating deficit.

If you have bad knees, there's no reason you have to do high impact cardio. Walking will do the job, though you might have to spend a long time at it to burn 500 calories, depending on your weight. FitnessBlender.com has low impact videos. Mix some strength training in there. Minimizing the rest in between sets (for instance using a circuit training format) can be a way to increase the cardio element of a strength session, especially if you are not lifting particularly heavy.

I was wondering if I could eat less instead of doing cardio for the same results? I exercise 5-6 days a week, 2 days doing strength training and the other days I do some form of cardio to burn around 500 calories. I hate cardio! Mainly because I have knee problems ( I probably should see doc for). It would be easy for me to cut my calories by 300 a day and exercise less .

Depends on what you mean by this (and apologies if you already get all this). The way MFP works is it sets a calorie goal for you based on the information you give it EXCEPT for your exercise plans. It assumes that you won't exercise until you log the exercise. SO, if you haven't been logging and eating back some calories from your cardio, in theory you could drop it and still be meeting your goal. Since MFP tends to give a lot of people pretty low before exercise goals (like 1200), what you don't want to do is deduct 300 calories from that.

Also, I'm with those who say cardio is for fitness more than weight loss (although I also do it because I enjoy it and can eat more). You don't have to do cardio you hate--I love running, but can't do it right now because of a knee injury of my own, and I hate cardio in the gym except for really good classes, so I mostly bike and swim and walk. But strength training is great too--I get the impression that some people mostly do that with good results, so I don't think you need to do cardio if you can't think of any you like.