It's not in your head. Here's why you could be eating healthy, but still feeling crummy.

Krissy Brady
October 16, 2020
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When you finally decide to improve your eating habits through positive dietary changes, like becoming one with the produce department and pretending there's caution tape around the junk food aisle, expecting to feel better once the changes are implemented is only natural. So, uh, why is it you instead feel queasy, gassy, moody and more?

"Once you make significant changes to your diet, it's quite common to have an adjustment period where you don't feel your best physically, mentally or emotionally," says Sheri Vettel, R.D., a registered dietitian from the Institute for Integrative Nutrition. "You may notice the onset of digestive upset, brain fog, irritability, aches and pains, or fatigue."

This can be extremely frustrating, but don't fret: "It's short-lived and usually a good indicator that you're making changes for the better," says Vettel.

Why Eating Better Can Make You Feel Worse in the Beginning

It's easy to assume the symptoms you're experiencing are due to a food allergy, sensitivity or intolerance, and an elimination diet might be necessary to figure out what foods are causing you bodily drama. But that's not always the case.

"In reality, it may only indicate you need to give your body more time to adjust," says Kansas City-based registered dietitian Cara Harbstreet, R.D.

The body relies on enzymes, hormones and numerous physiological processes to digest, absorb and excrete nutrients and substrates from the food we eat, Harbstreet explains, and many enzymes and hormones are only produced at the level needed. "If the body's suddenly asked to up-regulate and start producing more because you're eating differently, you may experience some uncomfortable symptoms at first," she says.

No matter the dietary change, you can support the process by drinking plenty of water and getting adequate amounts of sleep. "But if lingering symptoms persist, then it may be time to see a specialist or dig deeper to learn what may be causing the symptoms," says Harbstreet. Causes could include a nutritional deficiency or underlying condition.

To get to the bottom of why eating right is feeling so very wrong, experts offer up their top theories—plus, how to turn things around.

1. You've Slashed Your Sugar Intake

When you consume sugar, the brain releases dopamine, a pleasure-inducing neurotransmitter. "If sugar was regularly relied on for its mood-boosting benefits, quickly removing it from the diet can lead to strong sugar cravings and feelings of sadness and anxiety," says Vettel. You may also experience fatigue and nausea, as a result of the shift in the gut's microbial balance.

Instead of slashing all sugar from your diet at once, make one change at a time, such as reducing the number of teaspoons in your coffee or tea, or swapping out your afternoon soda for flavored carbonated water. This will also help it feel like a more sustainable change.

"This approach allows you to wean yourself off of added sugar in a way that works best for you, keeping sugar cravings to a minimum and reducing the chance of unwanted symptoms," says Vettel.

2. You've Gone Plant-Based

Eating more produce and fewer animal products may be an excellent decision for your health, but it can also lead to a major side of fatigue. "Going more plant-based can cause a decrease in nutrients like vitamin B12, vitamin D and iron—all of which are necessary for a host of processes in the body, including energy," says Trista Best, R.D., a registered dietitian at Balance One Supplements.

If you've gone plant-based and are feeling worse instead of better, you may want to begin by evaluating the nutrient content in your diet, specifically regarding these three important nutrients, says Best. There are several plant-based sources of vitamin D, iron and vitamin B12 to help you get what you need while still cutting down on animal products.

Besides tweaking how your diet's currently laid out, correcting potential nutrient deficiencies can be done through eating fortified foods or taking specific supplements.  It is important to be choosy with supplements, since they are not tightly regulated. For more, check out what one of our registered dietitians has to say about supplements.

3. You've Switched to Decaf

When you find yourself pouring a few too many cups of coffee or hitting the drive-thru more often than you'd like, reducing how often you consume caffeine is a great way to make room for healthier forms of hydration.

But, as any coffee connoisseur knows, ghosting caffeine cold turkey can be a physical and emotional nightmare. "Headaches, lethargy and irritable mood can all be possible symptoms as your body tries to recalibrate to being less dependent on caffeine to feel awake and alert," says Harbstreet.

It's always best to gradually decrease caffeine intake to avoid withdrawal symptoms—say, cutting back by one cup and letting your body adjust before decreasing again, until you've tapered off to your desired amount.

4. You've Cut Back on Carbs

Carbohydrates, the primary macronutrient in refined grains, increase serotonin release (best known as the happiness hormone), which may lead you to frequently consume carb-rich foods for the mood-boosting effect. "When refined grains are cut from the diet, you may notice mood changes, including sadness and irritability," says Vettel.

And if you drastically cut out grains overall (say, by going on a low-carb diet), you're likely to notice quite a few symptoms related to lower carb intake, including constipation, headaches, brain fog and lethargy.

Consider the power of sustainable shifts here too, says Vettel. Take an inventory of the common sources of refined grains in your diet, and decide on one small change you can start with. For example, swapping out white bread for 100% whole-grain bread. "Over time, you might even experiment with grain-free options, such as lettuce wraps or sweet potato toast," says Vettel.

Persistently feeling awful after going low-carb could mean that you've gone too low, in which case Vettel recommends consulting with a registered dietitian for support. "They can guide you toward lowering your intake gradually and making food choices that will be best for you, while also ensuring your nutrient needs are met," she says.

5. You've Amped Up Your Fiber Intake

The average American adult only consumes about half of the recommended intake of fiber per day, so increasing how much fiber you consume is an excellent move.

"But in return for increasing fiber, and ultimately beneficial foods like fruits, vegetables and fiber-rich grains, a person may experience bloating, gas and an overall sense of discomfort if they increase too quickly," says registered dietitian Lisa Bruno, R.D.N., founder of Well Done Nutrition.

When your digestive system isn't used to a diet that's higher in fiber, it'll take time for your body to adjust and process the fiber efficiently. "The adjustment is due to either the bulking effects or fermentation of fiber in the gastrointestinal tract, leading to bloating, gas and an increase in bowel movements (or constipation if you're lacking water intake and the fiber isn't moving itself through the GI tract)," says Bruno.

In these cases, Bruno recommends decreasing your fiber intake until these feelings subside, and then increasing your fiber intake gradually. (You should also make sure you're drinking enough water so there isn't an intestinal traffic jam.)

For example, add one additional serving of fiber to one meal or snack daily for one week and see how you feel. "A serving of fiber can be between 5-8 grams when you start off," says Bruno. "This might look like a medium pear for a snack (5.5 grams) or one cup of cooked barley (6 grams) as a side for dinner."

If your body doesn't give you attitude (or once it adjusts), add another additional serving during week two, and so forth, until you're eventually consuming the recommended daily amount (25 grams for women or 38 grams for men).

"During this time—and truthfully, all the time—look to consume 64 ounces of water per day or more," says Bruno. "This could look like four moments throughout the day where you drink 16 ounces at a time."

6. You've Freed Yourself from Dieting

Making the transition to intuitive eating is a necessary step toward healing your relationship with food and moving away from restriction and dieting for good.

It's also arguably better for overall health and well-being in the long run, as "there are no long-term benefits from the weight cycling that often results from repeated dieting attempts and can actually worsen health over time," says Harbstreet. (In fact, there are some pretty scary things that can happen to your body when you yo-yo diet!)

However, she adds, this initial phase of reintroducing foods and exploring what food freedom looks like can be tumultuous for both physical and emotional health.

"On the physical side, you may experience GI symptoms, from either an increase in the total amount of food you eat or the types of food you eat," says Harbstreet. "Fat, fiber and protein slow digestion and your body may need time to adjust to these changes. A little gas, bloating or discomfort is normal and natural; most people experience these and it's not necessarily a sign of an intolerance or food sensitivity."

On the emotional side, there might be feelings of overwhelm and chaos, especially when reintroducing foods that trigger fear or anxiety. "It may feel as if binge-eating is inevitable, or you may struggle with the temptation to return to dieting," says Harbstreet.

A registered dietitian or therapist who's experienced in this area can guide you through the process and equip you with the tools and resources necessary to successfully integrate intuitive eating into your life. But if that's not an option, Harbstreet recommends adopting a slow-and-steady approach to reintroducing foods.

"Rather than diving into a food free-for-all that can trigger your anxiety around eating certain foods, select one or two at a time and experiment with what it's like to enjoy unconditional permission to eat them," says Harbstreet.

As you start to gain confidence in the process, you can move on to other foods, food groups or eating experiences with the knowledge you gain from your initial trials, and continue to adjust course as you go along.