Well, it's like saying "to be healthy do we have to follow a certain plan". There are a million different ways to be healthy. You can jog daily. You can swim daily. You can ride a bike daily. You can be vegetarian. You can eat meat. But there are a few basic ideas that are common - you need to get exercise each day. You need to eat a diet that has all critical vitamins and minerals in it.
The same is true with low carb. All low carb plans are different in the specifics. But all of them are the same in the basics. Cut out non-essential, junk carbs - potato chips, chocolate chip cookies. Exercise, drink water. Following a plan makes it easier to do those things in a healthy manner.
The same theory is true for nuts. Some nuts are awful for you. Some are really good. If you had just one awful nut, is it comprable to eating 8,000 "healthy" nuts and having all that fat go into you? What if you're allergic to nuts? There's no simple answer.
Most low carb plans have you cut out nuts for the first 2 weeks because many people are allergic to nuts and don't even know it. They bloat or have bad reactions but don't realize it's the nuts that make them feel poorly. Cut them out for the first 2 weeks. When you add them back in, do so slowly so you can see how you react.
If you look at this chart -
http://www.bellaonline.com/articles/art581.aspif you're snacking on chestnuts, that is a ton of calories you're eating - it's like nature's candy.
