When working with lights, be they artificial or natural, the tendency when starting out is to light from the front, or at least at 45 degrees. But if you want to create something moodier, using your main light source as a backlight is possibly the quickest way to get something interesting.
Food photographer, Brandon Figueroa, from figandlight, illustrates this concept really well in his latest video. While he describes it as "looking into the light" as opposed to "backlight," the same thing is being demonstrated. It's a very common technique in filmmaking also, for a number of reasons. Specifically, shooting into your key light is a very easy and effective way of creating depth in an image, and it's also a handy way to reduce harsh shadows on your subject — you see this all the time in environmental/exterior portrait photography that employs natural light.
His comparison of the shots of spaghetti on a fork is a great example of how you could go either way depending on the look you're going for. Backlighting isn't necessarily better, it's just easier to create a more pleasing image that way. The version shot from the side, however, has a bit more punch to it — it's more textured and vibrant. While the more natural one would look great in a food magazine, I could imagine the punchier one on a billboard. It all depends on the context and execution. I say execution because shooting food with harsh light is not an easy thing to do well. The first person that comes to mind who is able to pull this off is our very own, Scott Choucino.
Which shot of the spaghetti do you prefer?