The answer of course depends on perspective and exactly what is meant by "media."  Given that media can include both TV and commercial media as well as books and magazines, there are both healthy and unhealthy food choices being celebrated by different parts of the media.

From a documentary such as "Supersize Me," that highlights the dangers of a diet high in sugar and sodium and food that is highly processed like much of the menu at McDonalds to the catchy and entertaining commercials produced by the fast food industry itself, the media pushes and advocates for both sides of the food choice debate.  "Food Inc." tries to portray all of the possible side effects of a fast food culture while also celebrating the possibilities and positives of a more well considered and thoughtful approach to both eating and producing food.

The radio and print ads that extol the great taste and convenience and low cost of fast food do the same thing for burgers and fries and shakes and other forms of "fast food."  They create an appealing message and push the consumer towards their products and away from perhaps healthier choices.

I would say that generally speaking the media's influence is not a good thing. To be sure there are some exceptions, like Jamie Oliver and his food revolution movement and some good documentaries on food and the importance of eating well or studies on how food is produced. However, there are so much more on unhealthy choices through the media. There is a reason for this. 

When it comes to the media, you have to sell airtime to advertisers. In the end, it is all a business. There is almost a conflict of interest, because companies that buy air time for commercials owns the media in a sense. So, when MacDonald's, Burger King, and a whole bunch of other vendors that produce unhealthy foods bombards the airwaves, television, and internet with their products, it creates for a society that is saturated with unhealthy food choices. In light of this, the media does not help much when it comes to healthy food choices.