While the human body needs proper nourishment to survive, nutrition is not a one-size-fits-all concept. A healthful diet can prevent or reduce the risk of certain diseases and chronic illnesses, but sometimes, certain foods can cause adverse reactions. Not everybody consumes, digests, metabolizes, and stores food in the same way.

If you notice that, within minutes of eating a particular food, you have a specific, physical reaction, you probably have a food allergy and should ask your doctor for a diagnostic test to confirm. However, if you have general bouts of lethargy, are in a constant state of fogginess, or always feel bloated and uncomfortable, you might have a food intolerance. In this case, an elimination diet can help determine sensitivities and may make a noticeable difference in your overall health and well-being.

Food allergies and intolerances may sound interchangeable, but they are actually quite different. An allergy is when your immune system reacts to an ingredient in food and fights against it. These reactions can be as mild as an itchy mouth or as severe as shortness of breath leading to anaphylaxis. The eight most common food allergies are eggs, fish, milk, peanuts, shellfish, soy, tree nuts, and wheat. (Click here to learn more about food allergies and product labeling.)

A food intolerance, on the other hand, relates to how your digestive system reacts when something in food cannot be properly digested. Lactose intolerance is the most common one—which occurs in individuals who lack the proper enzyme, lactase, needed to break down the disaccharide sugar found in milk—but, there can also be much less common intolerances involving spices like paprika, dill, and ginger; vegetables like asparagus and bell pepper; and fruits like banana and mango.

Consider the following:

• Track your meals and moods. For an entire week, take note of every single food item you eat, read the ingredients list on all labels, and log how you feel after eating. Are you bloated and gassy? Do you have less energy? Are you unable to focus?
• Make adjustments. Now that you have an idea of which foods may trigger which symptoms, entirely eliminate one of those items from your meals for an extended period of time—three to six weeks—or make a smart replacement. For instance, if dairy is the culprit, try almond or rice milk instead. If sodium is doing you wrong, add a squeeze of citrus or a flavorful dried herb where you normally would use salt.
• Be patient. It can take up to three days to notice if symptoms have been alleviated, so continue to track your foods, moods, and other signs during the elimination. If you find the eliminated food is unlikely to be the problem, try not to add it back until you have tested some of the other trigger foods on your list or slowly integrate it back into your regular diet and pay close attention if any symptoms act up again.

You know your body best. If you have puzzling symptomatic issues over months—or perhaps years—of your life, you might find an elimination diet brings to light unfavorable reactions to food(s) you consume regularly. With that finding, you can make informed decisions about what you eat going forward.

[A version of this article was written for, and first appeared in, YoffieLife.com on July 27, 2014.]