I’ve been hearing that Dark Chocolate is healthy and could help you lose weight/have beautiful skin. But, exactly what brand of dark chocolate?

http://www.webmd.com/news/20040601/dark-chocolate-day-keeps-doctor-away

Good dark chocolate like Dove Dark Chocolate bar has:
Epicatechin is a particularly active member of a group of compounds called plant flavoniods. Flavoniods keep cholesterol from gathering in blood vessels, reduce the risk of blood clots, and slow down the immune responses that lead to clogged arteries.

Cocoa Powder
Cocoa powder, which is low fat, would surely be a healthier way to get both our chocolate fix and our dose of flavanols. Alkalizing cocoa (or Dutch processing) produces a milder flavor and darker color but destroys most of the flavonoids. Since flavanol-rich cocoa is naturally bitter, Mars has worked hard to make it palatable. It sells a flavanol-rich series of snack bars and small chocolate bars.

CocoaVia snack bars are available online and also in stores such as Target, Walgreens, and Fred Meyer.
http://cocoavia.com/

CocoaVia bars have been shown in one small study to actively lower total and LDL (bad) cholesterol in those with elevated cholesterol levels, bolstering Mars’ claim that its flavanol-rich snack bars are heart healthy. More recently, Mars has launched a line of flavanol-rich beverage mixes, and Barry Callebaut offers a high-flavanol cocoa powder, which gives chocoholics a healthier, low-fat alternative to high-fat chocolate bars.

Actually cocoa, the nonprocessed type is better for you and you wouldn’t gain weight provided that it isn’t used in high calorie fatty dessert, but used in low fat healthy desserts and beverages. Natural (not dutch processed) is better for you.

Using Unsweetened Cocoa
There are two styles of cocoa - natural and “dutched.” The difference is an additional processing step. Natural cocoa is mildly acidic. Dutched cocoa has been alkalized (so its supposed to be smoother, less bitter and more soluble).

Substituting unsweetened cocoa for Dutch-Process Cocoa - 3 tablespoons (18 grams) unsweetened cocoa powder plus a pinch (1/8 teaspoon) baking soda.

Substituting Dutch-Process Cocoa for unsweetened cocoa - Leave out any baking soda called for in the recipe.

Substitute 1 (1-ounce) square of unsweetened baking chocolate with 1 tablespoon oil plus 3 tablespoons unsweetened cocoa.

Rule of Thumb:
Dutch process is alkalized and cocoa such as Hershey’s cocoa is non-alkalized. If your recipe calls for Dutch process cocoa and you don’t have any and you want to use Hershey cocoa, add a smidge of baking soda to even out the alkalinity and keep the cake from being coarse and dry.

And vice versa - if you are baking a cake and it calls for regular cocoa and all you have is Dutch-processed cocoa, just leave out any baking soda in the recipe.