In response to the comments about crack or other addict consciousness and the idea of indulging cravings... yes. It applies there too. The difference, however, is that when the indulgence involves substances that may be harmful or deleterious to the form, or if there is fear of such, the process of following or indulging the craving is inward.
We have an externally focused population, I understand, however the craving doesn't actually exist in the substance desired, it lives within the person experiencing the craving. "Following" the craving, then, is an inward process. Allow it to wash over the self, feel and "be" the energy of the craving. There is a reason for the craving that this process will reveal. And in the end, the benefits of discovering it far outweigh the "danger" or discomfort of allowing the craving to temporarily consume the consciousness of the individual.
The reason the person has an addiction or craving is always valid. Trusting that is almost opposite what the mind and ego does with such things. In fact, the attempt to deny, refrain, contain, or control cravings is the very foundation of the cycle of addiction. Discovering the root cause for the compelling draw toward a substance will yield much and free the consciousness. So to answer another question of why would mother nature or a natural force ever draw us away from something pure and healthy? Because of the learning and self-discovery it will produce. As always, the key is one's consciousness applied to the process.
Making the conscious decision to honor the craving, call all aspects of self to the task. There will be feelings, thoughts, guidance and all other resources available in the experience, if the intent is to open and discover through the indulgence. Again the stance at the onset is important. Open to discover what is there to discover, or close oneself off to discover proof of a suspicion, and your results will reflect that initial intent.
"The most important decision you have to make is whether you live in a hostile or friendly universe."
~ Albert Einstein
The real voyage of discovery consists not in seeking new landscapes, but in having new eyes. ~Marcel Proust
The evolution of humanity is an evolution of the heart. The path is through the heart.