Lack of eating doesn't cause a miscarriage. When I was pregnant I was eating maybe once a day or once every other day. I lost over 25 pounds while pregnant from extreme nausea/vomiting and when I delivered I was lighter than my pre-pregnancy weight. It causes more harm on your own body, as the baby takes everything it needs from you and you pay for it later. It's important when you do eat to eat high calorie foods.
I've been the same way for the past two months, no appetite whatsoever and I've been forcing myself to eat. I dont know if this is just a fluke for me, but I've been carrying around G2 gatorade and sipping on that throughout the day (really helps with nausea) and it tends to give me a little more of an appetite. I read a tip on this website that has worked for me too. When it is time for a meal, instead of looking around the kitchen deciding what is appetizing, I sit down and relax and just think about what would taste good right now. That way, I'm not seeing the unappetizing food that will make me nauseous and normally once I decide what I might want for a meal I get a little hungrier.
Try snacking & nibbling here & there throught the day...