What are the side effects of eating no processed foods?

October 5, 2025 •

5 min read

According to research from The BMJ, consuming a high amount of ultra-processed foods is linked to an increased risk of over 30 adverse health outcomes, so it's no wonder many people are shifting their diets. When you stop eating processed foods, your body goes through a temporary adjustment period, which can cause some unexpected side effects before the long-term health benefits emerge.

Quick Summary

Eliminating processed foods can cause temporary withdrawal symptoms like headaches, fatigue, and irritability before leading to significant improvements in energy levels, digestion, and overall health. The transition requires a shift in habits, but the long-term rewards far outweigh the initial challenges. Focusing on whole, nutrient-dense foods is key for a successful dietary change.

Key Points

Initial Withdrawal Symptoms: Expect temporary side effects such as fatigue, headaches, irritability, and strong cravings as your body adjusts to the lack of added sugars and salt.
Positive Long-Term 'Side Effects': After the initial phase, a no-processed-food diet leads to higher energy levels, improved mental clarity, and better sleep quality.
Digestive Improvements: An increase in fiber from whole foods can cause temporary bloating but ultimately leads to a healthier gut microbiome and better digestion.
Reduced Chronic Disease Risk: By prioritizing nutrient-dense whole foods, you can lower your risk of developing chronic conditions like heart disease, type 2 diabetes, and certain cancers.
Enhanced Mood and Well-being: Eliminating ultra-processed foods is linked to reduced symptoms of anxiety and depression, supporting overall mental health.
Challenges Are Manageable: While processed foods are convenient, a successful transition can be achieved through meal planning, mindful swaps, and reading food labels.
Focus on Progress Over Perfection: It's not about complete restriction but about making sustainable changes and building a foundation of whole, nutritious foods.

The Initial Jolt: Temporary Side Effects and Withdrawal

Embarking on a diet with no processed foods is a significant change, especially if processed items were a staple of your diet. Your body has grown accustomed to the high sugar, salt, and fat content engineered into many convenient products. The first few days or weeks can feel like a withdrawal period, as your body rebalances and adjusts to the change.

Mood Swings and Fatigue

One of the most commonly reported initial side effects is a fluctuation in mood, including irritability and even depression. This is largely due to the withdrawal from added sugars and refined carbohydrates, which can cause significant blood sugar spikes and crashes. As your body moves away from this dependency, it's normal to feel more tired or sluggish initially. This fatigue is a temporary phase as your system learns to regulate its energy from whole, nutrient-dense sources rather than quick, sugary fixes.

Digestive Adjustments

An increase in fiber from fruits, vegetables, and whole grains is a hallmark of a no-processed-foods diet. While beneficial in the long run, this sudden dietary shift can initially cause some gastrointestinal discomfort. You might experience bloating, gas, or changes in bowel movements as your gut microbiome adjusts to the new, more complex fiber sources. This is a positive change, as fiber feeds the beneficial bacteria in your gut, but it can be uncomfortable at first.

Strong Cravings

Processed foods are often formulated to be "hyper-delicious," triggering the reward centers in your brain and creating a compulsive habit. When you remove these highly palatable items, your brain can crave them intensely. These cravings, along with headaches caused by caffeine or sugar withdrawal, are part of the detoxification process. Patience and preparation are key to pushing through this period.

The Real 'Side Effects': Positive Transformations Await

Once the initial withdrawal period subsides, the true and long-lasting effects of a whole-foods diet begin to emerge. These are not drawbacks but rather the beneficial outcomes of proper nutrition.

Increased Energy and Mental Clarity

As your body stabilizes its blood sugar and gets sustained energy from nutrient-rich foods, you will likely notice a significant boost in energy levels and mental focus. Without the sugar crashes and inflammatory burden of processed foods, your cognitive function can improve, leading to better concentration and productivity.

Improved Digestion and Gut Health

The temporary digestive discomfort paves the way for a healthier gut. The increase in fiber acts as a prebiotic, nourishing the beneficial bacteria in your gut. Over time, this leads to more regular bowel movements and a stronger gut barrier, which is crucial for overall immunity and mental well-being.

Enhanced Mood and Better Sleep

Research suggests that diets high in ultra-processed foods are associated with a higher risk of anxiety and depression, while whole foods are linked to improved mental health. By removing artificial additives and balancing blood sugar, a whole-foods diet can stabilize mood and improve sleep quality. Certain whole foods are natural sources of melatonin and tryptophan, which help regulate sleep cycles.

Sustainable Weight Management

Processed foods are often calorie-dense and lack satiety due to their low fiber and high sugar content. A whole-foods diet, rich in fiber and lean protein, promotes a greater sense of fullness, which can lead to reduced calorie intake naturally. This can result in healthy and sustainable weight loss without the need for strict calorie counting.

Whole Foods vs. Processed Foods: A Comparison


Aspect	Whole Foods Diet	Processed Foods Diet
Nutritional Value	High in essential vitamins, minerals, and fiber; nutrient-dense.	Often low in nutrients (unless fortified); high in empty calories.
Convenience	Requires more time for planning and preparation; shorter shelf life.	Highly convenient, ready-to-eat, and long shelf life.
Cost	Can sometimes be perceived as more expensive, though meal prep and seasonal buying can reduce costs.	Often cheaper upfront, but high long-term health costs.
Health Impact	Promotes gut health, stabilized blood sugar, reduced chronic disease risk.	Linked to obesity, heart disease, diabetes, and other chronic conditions.
Satiety	High fiber and protein content leads to greater and longer-lasting feelings of fullness.	Engineered to be over-consumed; less filling per calorie.
Ingredients	Simple, recognizable ingredients in their natural or minimally altered state.	Contains additives, preservatives, artificial flavors, and excessive salt and sugar.

How to Manage the Transition and Maintain a Whole-Foods Diet

Making a complete switch overnight can be overwhelming. A gradual approach is often more sustainable and less jarring for the body. Here are some practical tips to help you manage the journey:

Start with 'Addition, Not Subtraction': Instead of focusing on what you're cutting out, focus on what you're adding in. Increase your intake of fruits and vegetables at every meal. This naturally displaces processed options over time.
Become a Label Detective: When you do buy packaged goods, read the ingredient list. The fewer ingredients, and the more recognizable they are, the better. Avoid items with long lists of chemicals, artificial flavors, and added sugars.
Master Meal Prep: Busy schedules are a main reason people turn to processed convenience foods. Set aside time once or twice a week to chop vegetables, cook grains, and prepare large batches of meals like soups or stews. This ensures you have healthy options readily available.
Go Brown: A simple swap is to replace refined grains like white rice, white bread, and white pasta with their whole-grain counterparts. This boosts your fiber intake and provides more sustained energy.
Drink Smart: Replace sugary sodas and juices with water, sparkling water, or unsweetened tea. Adding fresh fruit or herbs to water can add flavor without the sugar.
Embrace Mindful Indulgence: It's unrealistic for most people to never have a processed food again. The goal is progress, not perfection. Allow for occasional, conscious indulgences while making whole foods the foundation of your diet.

Conclusion

While eating no processed foods may present some temporary side effects like irritability and fatigue during the initial transition, these are simply signs that your body is rebalancing from its reliance on sugar, salt, and additives. The true and lasting 'side effects' of this dietary change are overwhelmingly positive. Improved energy, mental clarity, digestive health, and mood, alongside a reduced risk of chronic diseases, are the long-term rewards for making this nutritional investment. By starting slow, planning ahead, and focusing on whole, natural foods, you can successfully navigate the challenges and enjoy a more vibrant and healthy life.

Visit Healthline for more practical tips on transitioning to a whole foods diet.

Frequently Asked Questions

When you quit processed foods, your body initially goes through a withdrawal period, causing symptoms like fatigue, irritability, and headaches. After this adjustment phase, you experience significant benefits, including improved energy, better digestion, weight loss, and reduced risk of chronic diseases.

The initial adjustment period can vary, but many people experience withdrawal symptoms for the first few days to a couple of weeks. With consistency, positive changes in energy levels, digestion, and cravings can become noticeable within a few weeks to a couple of months.

Yes, cutting out heavily processed foods can lead to detox-like symptoms. These are mainly withdrawal symptoms from high levels of sugar, salt, and fat. Common symptoms include headaches, tiredness, irritability, and intense cravings, which are temporary.

For most people, a diet with absolutely no processed foods is unrealistic. The goal is to minimize ultra-processed foods (like sugary snacks and pre-made meals) while prioritizing whole, natural foods. Some minimally processed foods, such as frozen vegetables or canned beans, can still be part of a healthy diet.

Great replacements for processed snacks include fresh fruits, a handful of unsalted nuts, veggies with hummus, hard-boiled eggs, plain Greek yogurt with berries, or homemade kale chips. These options are filling and nutrient-dense.

While some whole foods can seem more expensive, a focus on meal planning, cooking from scratch, and buying seasonal produce can often be more cost-effective in the long run. The long-term health benefits can also significantly reduce future medical expenses associated with diet-related diseases.

The first positive signs of eating healthy can include feeling more energized and less sluggish after meals, improved sleep quality, fewer cravings for unhealthy snacks, and better digestion.