ok, so if you are prone to binge eating or just eating huge portions whenever you do eat, then you need to start filling up on healthier options that still taste good. One of the main reasons people can't break the over eating cycle is because the majority of foods that people binge on are non-nutritional junk. Your body requires a certain amount of vitamins and minerals to function properly, if you are eating processed foods or high fat, high sugar, high refined carbohydrate foods then you will not be giving your body the nutrition it needs. This will set you on a cycle of craving more and more food as your body is desperately trying to get that nutrition.
If you are saying, but I do eat some healthy meals. My wife's cooking is healthy! Then ask yourself whether u are snacking on processed foods in between! If the answer is yes, then the high sugar content of the junk will give you an initial energy burst, only to be followed by a severe slump. This slump then causes the body to want more sugar in order to get that high again. So once again a vicious cycle of cravings.
So how to combat this??? Well, I definitely wouldn't suggest going on a totally strict diet because you will just fail! You need to make slow changes to your diet and incorporate some form of exercise that you can do (I'll get into that in a minute). The first thing I would suggest to stop the cravings and to give you steady energy levels is to eat some form of protein with EVERY meal. Protein never causes blood sugar fluctuations which means it never causes cravings!!! In case you don't know what protein is here's some examples: meat, eggs, low fat dairy such as cottage cheese, low fat cheese, low fat sugar free yogurt (u can add a little bit of honey to sweeten), tofu, nuts and seeds, protein powder, and I'm sure there's more just Google it.
So what I am saying is, if you eat even a piece of fruit - have a lump of cheese with it. If you have some toast for breakfast in the morning - stick an egg on it. Even if you have to have some sort of junk choose something with a higher protein content like ice cream over chocolate! The protein content of all foods is on the nutritional label so start reading them.
The other big principal to follow is eat what you should before what you would. Eat the good stuff first and you will have less space for the bad stuff! Can you see that it is much easier to eat a whole bag of crisps than it would be to snack on steak or chicken breast! Imaging how full you would get if you sat in front of the tv and started eating steak instead of those crisps.
In terms of exercise - there are plenty of exercises you can do that will not harm your knees!!! Once again, Google it, but off the top of my head - push ups, sit ups, triceps dips, any form of upper body weight training, Pilates and Yoga that are mat based and I'm sure there's plenty more. Any exercise will burn calories. Don't allow yourself to cop out because of your knees. Even if you do 5 push ups that's better than nothing.
You can lose weight without exercise, but it definitely helps a lot if you can just do something. Get yourself some workout dvds to follow if u r unsure of some exercises. You can even be so specific as to google workout dvds for bad knees. I guarantee you'll find something.
Good Luck!