It depends on how severe your tmj symptoms may be in terms of whehter you can chew and swallow or not - from a nutritional standpoint try and maintain a balanced diet much as you would if you were symptom free - even if you have to chop, grind or puree your food first and if you can swallow, supplement your diet with vitamins as normal too - or purchase the liquid versions of them.
If your symptoms prevent you from chewing and swallowing normally there are many soft foods you can eat and still maintain a healthy diet - yogurt, cheeses, puddings, smoothies and shakes, vitamin fortified drinks like Ensure, eggs, soggy or mushy cereals, etc. I find over cooking vegetables so they become mushy makes them eaier to swallow and even though this does diminish some of their nutritional value its better than not eating them at all. In terms of meats - avoid any type of hard chewing - however using a slow cooker or making a casserole often renders the meat very soft so it requires less chewing. In terms of fruits - and even vegetables - you could also use a juicer and create your own concoctions.
If the issue is more that you have lost your appetite as a result of the tmj - due to nausea or chronic pain - or if your digestive track is also affected - I found the shakes and fortifed drinks the most tolerable.
When you really put your mind to it you will find there are plenty of things you can still eat if you prepare them differently - so experiment a bit.
Also - this of course should go without saying - but limit how much food you put in your mouth at one time - eating does tend to take on a new dimension with tmj and you will probably find the amount of time to finish or complete a meal will be 2-3 times more than you would normally. If you find that your jaw and muscles become totally fatigued during meal time so much so that you end the meal without being full then instead of limiting yourself to 3 meals a day increase it to several small meals and snacks spreadout throughout the day - however avoid eating too close to bedtime.
Welcome to our forum. Sorry that you're having problems with your tmj.
Thelma Louise gave you excellent advice.
I've had problems with my tmj for 26 years, and my diet has been modified for that entire time. I've found that if I listen to my body it will tell me what to eat and how much. Like Thelma Louise said, it will take more time to eat, don't get frustrated. I found that it works best to eat small meals throughout the day.
You don't say if you have trouble opening your mouth, if your muscles are in spasms. If you give us a bit more info, we can pinpoint some more info for you.
Please keep us posted, and let us know how we can help you.