I don't agree with Muumi. Popcorn can be an amazing snack, but buy an air popper and do it that way. Put some herbs and spices on it (stay away from straight salt and NO BUTTER OR OIL) and you're golden. I've recently lost close to 50 lbs and it wasn't easy but it's doable.
The problem is, places like the 'Golden Corral' might SEEM to have healthy options, but their 'healthy' options aren't that healthy at all. They use low-quality oils that help you pack on the pounds and cheap alternatives to 'good cooking' that means a plate of veggies / meat / potatoes there vs. a plate of veggies / meat / potatoes at home has a HUGE difference not just in calories but in fats and the quality of the fats you're getting. Your body needs specific fats to work off of, supplying the wrong fats will just make your body store fats.
I'm not going to lie to you. For probably four-five months out of seven (total 'dieting') I starved myself of the calories I needed. I ate between 400 - 600 calories a day and exercised it all off... and I probably lost half (less) as much then as I did when I was eating higher amounts of 'balanced' calories. That said, you need to look at a few things. Consult your Dr. and different websites... The typical answer is 'don't go under x amount of calories' or 'you need x amount of calories' but it varies GREATLY with your height / current weight. When I was eating balanced meals I was eating between 1000 - 1200 calories a day and felt fine, because I'm insanely short and because the food I was eating was good food. The point is, you need to do research beyond a couple of websites. I sat for hours calculating EXACTLY how much I needed to take in- not just calories but fat and sodium, carbs, etc. (remember, the labels on packaged food is based on 2000 calorie a day diets, I need close to half that so that '20% of your daily carbs' translates into '40%').
I also found some awesome 'super foods' that took a bit of getting used to but hey! Now I love them. Quinoa - it's a grain, not gonna lie, it tastes weird at first but it's an excellent replacement for rice / pasta. If you're going to have rice skip the white and skip the brown, go for black rice. It's a bit of a pain to prepare, but if you get ahead of it (leave it to soak over night) it's just as easy. No potatoes, there's really no 'value' in a potato. Yams, maybe, but no potatoes.
Like I said, 'Golden Corral' type restaurants use low quality oils to cook their meats, so any beef etc. you're getting there is even WORSE for you than it regularly is. Turn to lean meats, only eat chick and (ugh) fish. I always hated fish (my dad drilled it into me at an early age that 'fish give you worms'
great influence) but have forced myself to start eating it... and guess what, I like it!).
Lentils are a good one too, and chick peas. Higher in calories but a good sturdy protein that is harder for your body to break down.
Multigrain / whole wheat bread isn't bad for you, but have you tried Sprouted Grain? It doesn't taste much different but it is MUCH better for you and definitely aids weight loss.
I'd start tracking your calories EXACTLY, cut out the 'going out' food as much as possible and if you have to find somewhere new to go. I find that 'vegetarian' or 'vegan' restaurants tend to be super conscious of the oils they use, etc. so maybe try something like that?