Sure, there are perfectly legitimate reasons to "listen to our bodies." For example, noticing a sharp chest pain or an allergic reaction (a real, diagnosed one) to food. However, there are many people who make a completely irrational attempt to justify their "need" to consume animal products by using the "listening to my body" argument. As a registered dietitian, this is probably one of the most irksome arguments I hear, because it's simply untrue.
Thank goodness that we don't have to rely on mere thoughts and feelings to determine what nutrients humans need to consume to stay healthy. In fact, there's a thing called the scientific method, and it's an incredibly precise way of gathering and deciphering information. We have used it to compile decades of nutrition research that have resulted in established recommendations for the nutrients our bodies need to thrive.
We have even been able to use this body of scientific evidence on human nutrition to make the determination that we simply don't need to consume animal products to survive. The Academy of Nutrition and Dietetics has put this issue to rest in a single position statement:
It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes.
Evidence-based nutrition recommendations tell us the appropriate amounts of macro and micronutrients the general population needs to stay nourished. How we choose to obtain those nutrients is completely up to us, and there's certainly no established recommendation for the amount of animal products we need to consume, because they're not essential. We can get all the nutrients our bodies require while consuming a completely plant-based diet. This isn't propaganda or zealotry; it's a simple scientific fact.
So, let's please stop using the "listening to my body" excuse, because it's completely false. Let's just be truthful and say, "I'm not ready or willing to go vegan at the moment." There are certainly many debates we can have surrounding the vegan lifestyle, but whether or not we need to eat animal products to be healthy isn't one of them. No one needs to "listen to their body" to decide if they can go vegan or not.