The Whole30 is one of the hottest diets out there and, in our opinion, for very good reason. It gives you a break from the crappy processed food and puts the focus on eating more animal proteins (ideally grass-fed, organic, wild, and pasture-raised), vegetables, fruits, nuts, and certain packaged foods that are made with minimal ingredients.

Unfortunately, though, some people feel cold symptoms creep up during their first week or so on the Whole30. Hold up, that doesn’t mean you should run the other direction toward all the ice cream, chips, and dips, but if you’re wondering why you might be getting a cold when you’re trying to do some good for your body, let’s talk about it.

Why do some people get a cold on Whole30?

Think about it. If you’re used to eating yogurt with granola for breakfast, a turkey sandwich with chips for lunch, pita chips and hummus for a snack, and a cheeseburger and fries for dinner, it’s pretty obvious that once you start the Whole30, your body is going to be going through some big changes. And TBH, you might just need a minute to adjust.

When you start any new eating plan, you could potentially be eating fewer calories than what your body is used to in a typical day. Let’s be clear: We don’t think you’re going to go hungry on the Whole30—there are far too many good recipes to enjoy that can fill you up—but by restricting yourself from certain foods in your normal diet, you could be eating fewer calories than you normally do without even realizing it. So make sure you’re getting plenty of food and following the Whole30 plan correctly.

You’ll also want to make sure you’re getting enough of these essential vitamins and nutrients to help prevent a common cold:

  • Zinc: You can find zinc most commonly in foods like dairy, whole grains, meat, fish, nuts, and beans. Keep in mind, you’re removing dairy, grains, and pulses, so make sure you’re getting your seafood, steak, and almond butter fill.
  • B6: B6 is readily found in meat, so carnivores are probably in the clear. But if you’re a vegetarian and on the Whole30, you will want to up your intake of foods like sweet potatoes, avocado, and bananas.
  • Vitamin D:While commonly known as a bone-building nutrient, vitamin D has recently been shown to have immune-boosting benefits as well. Since the majority of our dietary vitamin D comes from dairy (a big Whole30 no-no), Whole30 dieters will want to go for more fatty fish and eggs, and consider a supplement to get enough.
  • Folate is typically consumed through legumes and fortified pasta and flour, all of which are off-limits on Whole30. To compensate, make sure you’re adding plenty of folate-rich dark green veggies by throwing spinach and kale in your salads, soups, and smoothies.
  • Iron is abundant in meat products, but since the plant-based sources are off-limits (that is, no legumes or enriched flours, pasta, or cereal), vegetarian friends may want to speak to a doctor or dietitian about a supplement during this 30-day diet.

What are other potential symptoms common during the Whole30?

You might be feeling a few other symptoms early on in the Whole30 game. Again, most of this is your body adjusting to this healthy eating plan, but here are the common Whole30 symptoms some people might experience.

Brain Fog and Fatigue

Some Whole30 dieters describe getting headaches, fatigue, crankiness, and brain fog, likely all related to being in a low-carb state, especially if that’s not something you’re used to. While not technically a ketogenic diet, the grain-free limitations on Whole30 may put you into a state of ketosis, where your body switches from glucose as its energy source to running on ketone bodies. Since this isn’t your brain’s usual form of fuel, it can come as a bit of shock to the head and can take a bit of time to adjust to. Give it a week or two, and you’ll be seeing rainbows and butterflies eventually.

Digestive Woes

Any time you drastically change your diet, your gut microflora (a.k.a. the good bacteria) tends to evolve and change. This isn’t necessarily a bad thing, but it can cause some mild gas, bloating, and irregularity as your body readjusts. You may also be cutting out high-fiber legumes and whole grains on Whole30, which may leave you feeling a little more backed up than usual. Be sure you’re doubling down on the high-fiber veggies to ensure you’re getting your 25-38 grams each day.

So how long will the symptoms last?

Depending on your diet prior to Whole30, any unpleasant symptoms will probably dissipate within one to two weeks. Once your body starts to adapt to being fueled by ketones and your gut microflora repopulates, you’ll hopefully be in the clear.

The Takeaway

Don’t let this scare you off from doing the Whole30 because there are many people who get through all 30 days with flying colors. Plus, even if you do have some symptoms, just remember you’re doing something good for your body and eventually you’ll be flying high. Just be sure to follow the plan correctly, allow your body to rest as it goes through changes, and load up on essential vitamins and nutrients to stay healthy.