The Science Behind Whole30
The Original Whole30

The science behind the Original Whole30

Your life-changing results start with the Whole30’s unique elimination protocol.

The Science Behind Whole30The Science Behind Whole30The Science Behind Whole30
What is the Whole30?

What is the Whole30?

You may have heard Whole30’ers describe the program as a 30-day self-experiment or a “reset.” We love that, because those ideas reinforce the fact that the Whole30 is not a weight-loss diet. But “reset” isn’t a real scientific term. So what is the science behind Whole30?

The Whole30 is based on the framework of an elimination diet, which many healthcare professionals consider the gold standard for identifying food sensitivities or adverse food reactions. The Whole30 goes one step further by combining the benefits of an elimination diet with the science of behavior change, helping you create new habits, reconnect with your body, improve your relationship with food, and build self-confidence.

Our original tagline from 2009 said, “let us change your life.” Since then, millions of Whole30’ers have said the program truly was life-changing, well beyond health, with the benefits carrying over into every area of their lives. You can see evidence of this throughout our database of Whole30 testimonials and success stories.

Elimination diets

Elimination diets

The elimination diet concept was first proposed by Dr. Albert Rowe in 1926 and is still considered the gold standard in identifying the foods that work best for you. Elimination diet protocols can be highly effective, accessible, low-cost tools for identifying food sensitivities (undesirable symptoms after eating certain foods) and intolerances (the inability to process or digest certain foods). Every elimination diet has two phases:

The elimination phase omits a specific food or group of foods known to cause adverse reactions or uncomfortable symptoms in some people. This elimination period generally lasts for 2-6 weeks, allowing enough time for the body to heal and repair.
During the structured reintroduction period, eliminated foods are brought back into the diet one food or food group at a time, every 2-3 days, returning to the elimination protocol in between.
The goal of an elimination diet

The goal of an elimination diet is to:

  • Remove food components that may be causing issues
  • Improve blood-sugar regulation and metabolism
  • Heal your gut
  • Calm your immune system (systemic inflammation)
  • Identify foods causing negative responses or unwanted symptoms.

How does the Whole30 work?

What to expect during your Whole30 elimination and reintroduction

Elimination Phase

The elimination phase of the Whole30 lasts 30 days

Elimination Groups

You’ll completely eliminate added sugar, alcohol, grains, most legumes, and most forms of dairy

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The Pancake Rule
The Pancake Rule

During elimination, you also cannot recreate baked goods, sweets, and other comfort foods, even if they’re made with compatible ingredients

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Take it slow
Reintroduction Phase

Reintroduction lasts 10-14 days; or longer if you choose

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Reintroduction Groups

You’ll reintroduce the above food and beverage groups one at a time, carefully and systematically, and compare your experience

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Food Freedom

Following reintroduction, you’ll take what you’ve learned to create a personalized, sustainable nutrition plan that works for your unique body

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Benefits of the Original Whole30

The Whole30 eliminates foods commonly known to cause inflammation or unwanted symptoms—such as GI distress (bloating, gas, constipation, diarrhea), skin irritation (eczema, psoriasis, acne), headaches or migraines, seasonal allergies, brain fog, anxiety, fatigue, and joint pain or swelling, among others. The Whole30 also eliminates foods that commonly contribute to cravings or an unhealthy relationship with food. For a host of potential benefits, see our Whole30 Non-Scale Victory Checklist.

The process not only helps you identify the foods that may be having a negative effect in your body, it can also bring about general improvements in energy, sleep, focus, mood, and self-confidence. The program is designed to reset your idea of “normal,” giving you a new baseline for what it means to feel good and perform optimally.

During Whole30 reintroduction, you’ll bring back added sugar, alcohol, non-gluten grains,  gluten-containing grains, legumes, and dairy one food group at a time, returning to the Whole30 for 2-3 days between groups. This allows you to effectively evaluate the impact each group may be having on your body, while allowing any negative symptoms that may arise time to calm before reintroducing the next group.

In a January 2023 survey of 690 Whole30 alumni, 97% said they achieved most or all of their goals for the program. The most commonly reported benefits include:

  • Reduced sugar cravings
  • Better digestion
  • Improved energy
  • Improved sleep
  • Better focus
  • Improved mental health
  • Better self-confidence
  • Less pain and inflammation
  • Reduction or elimination of symptoms (acne, allergies, migraines, asthma, anxiety, joint pain and swelling, and more)

Whole30 Program Rules: Elimination

It’s important to note Whole30 doesn’t eliminate foods because they’re “bad.” There are no universally good or bad foods, and Whole30 does not assign morality to food (or to you when you eat food). The Whole30 eliminates food groups shown in the scientific literature and in our clinical experience to be commonly problematic (to varying degrees, across a broad range of people).

The Whole30 eliminates these food groups because they’re unknown. These foods can be problematic, and the best way to determine whether or not they’re problematic for you is to eliminate them completely, reintroduce them carefully, and compare your experience.

Some foods eliminated during the Whole30 (like dairy, wheat, peanuts, and soy) are four of the top eight food allergens. Other food groups are eliminated due to the potential impact they might have on your cravings, metabolic health, digestive system, and immune system. Let’s take a closer look.

When overconsumed, added sugar has been demonstrated to have a negative impact on cravings, blood-sugar regulation and metabolism, digestion and gut health, and systemic inflammation. While artificial sweeteners and sugar alcohols aren’t believed to promote blood-sugar dysregulation to the same degree, they can also contribute to negative body, GI, and mood symptoms.

Overconsumption of alcohol has been shown to have a negative effect on cravings, blood-sugar regulation and hormonal balance (especially sex hormones), gut health, and systemic inflammation, particularly impacting the nervous system and brain.

Whole grains provide fiber, vitamins, minerals, and other nutrients. However, different protein structures in grains have been found to create transient increases in gut permeability, triggering an immune response, and promoting systemic inflammation. Inflammation can also be the result of impaired metabolic health or blood-sugar control when grains (especially refined versions) are consumed in excess.

Legumes and lentils can be a nourishing food for the gut and overall health. But for some, specific carbohydrates in beans and lentils can cause gastrointestinal symptoms like gas, bloating, and indigestion. Soy and peanuts also fall into this category and can promote gut disruption, systemic inflammation, and other negative health symptoms if you are sensitive.

Dairy can offer a host of benefits, including bone health and heart health, and is a good source of protein, calcium, B vitamins, and vitamin D. However, not everyone tolerates dairy well. The sugar (lactose) or milk proteins (casein or whey) found in dairy may contribute to digestive disruption, skin issues, allergies, or asthma.

Some foods that fall under this rule are bread, tortillas, pancakes, cookies, pasta, cereal, potato chips, and fries. During elimination, you’re asked not to recreate these foods with compatible ingredients. The Whole30 encourages you to swap these foods for more nutrient-dense options, and helps you discover new tactics for coping with stressors.

What happens after the Whole30?

What happens after the Whole30?

As with other elimination diets, the Whole30 is not recommended to be followed long-term. It is a short-term protocol to help you create a long-term nutrition plan that works for your unique body, based on the knowledge gained during elimination and reintroduction.

The Whole30 is not prescriptive. We don’t believe everyone needs to (or should) eliminate all of these food groups forever. After elimination and reintroduction, you’ll know which foods work well in your system, and which do not. Using our follow-up book Food Freedom Forever, you’ll take what you’ve learned from the Whole30 to create your own healthy, sustainable, personalized diet—what we call your “food freedom.”

Most people choose to continue to eliminate foods they don’t tolerate well, or only include them in certain contexts or in limited amounts, while continuing to enjoy all of the foods they’ve discovered work well for them. Everyone’s food freedom looks different, as it is based on each person’s unique experience with the Whole30.

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Learn more about the science behind the Whole30 with these commonly asked questions.

Habit research says it can take anywhere from 18 to 254 (!) days to make a habit stick, depending largely on how emotionally tied you are to that habit. However, one study in 2021 found on average, a new habit takes 59 days to solidify. Creating new habits with food can be an emotional challenge, but asking someone to follow a strict elimination protocol for two months (or longer) isn’t reasonable or necessary for our purposes. In our decade-plus of clinical experience, we’ve found 30 days is the sweet spot. It’s long enough for you to see dramatic, life-changing results, but short enough to make the program feel attainable. (And when you factor in 10-14 days of reintroduction, you’re already three-quarters of the way to that 59-day benchmark!) *Source: The British Psychological Society

In order to accurately determine how certain foods are impacting your body, you need to completely eliminate them for the prescribed period of time. Eating even small amounts of foods to which you are sensitive can disrupt the process and interrupt your healing. Complete elimination, on the other hand, can bring about improvements in any number of symptoms or negative health effects, and makes it easier to identify potentially problematic food(s) during reintroduction.

Rushing through reintroduction can have the same negative consequences. Reintroducing food groups too quickly, or reintroducing too many at the same time, will make it hard (if not impossible) to accurately evaluate the impact of these foods. You won’t be able to identify which food flared your symptoms, tanked your energy, or disrupted your digestion.

To make the most of your Whole30 self-experiment, completely eliminate all of the recommended food groups for 30 straight days, then reintroduce carefully and systematically, one food group at a time, allowing 2-3 days between food groups. Read The Science Behind the Original Whole30 here, and The Science Behind the Plant-Based Whole30 articles.

Both programs offer a 30-day elimination and structured reintroduction period, with the goal of identifying food sensitivities, creating new habits, and restoring a healthy relationship with food. The Original and Plant-Based Whole30 programs differ only in their protein and fat sources, and in the length of time the programs have been available. The Original Whole30, founded in 2009, includes high-quality animal protein and encourages the use of some animal fats while eliminating legumes, including peanuts and soy. The Plant-Based Whole30 was launched in March 2022, after two years in development. The Plant-Based Whole30 does not include any animal protein and fats. It uses beans, lentils, peas, soy, compatible protein powders, nuts, and seeds to ensure adequate protein; and includes only plant-based fat sources.
Nope! Each program was carefully designed to function as a stand-alone, discrete elimination and reintroduction protocol, with carefully selected parameters that have proven incredibly effective for the vast majority of people who complete the program. Once you choose a program, please complete it exactly as written, unless your healthcare provider directs you otherwise. Read the Original Whole30 Program Rules, and the Plant-Based Whole30 Program Rules.
In 2018, Catherine Moring, PhD, RDN, BC-ADM, CDCES, who is Executive Director of the James C. Kennedy Wellness Center in Mississippi, conducted a pilot study with 45 Original Whole30 participants and shared her results with us. Dr. Moring and her team provided education about the side effects of chronic inflammation, the benefits of an elimination diet, and the Whole30 Rules and Recommendations. They also supported participants by teaching them how to prepare and enjoy minimally-processed, whole foods without focusing on calorie counting or food restriction. Dr. Moring’s team collected bloodwork and biometrics from the 45 study participants before and after completing the Original Whole30. Although the results of this cohort study have not yet been peer reviewed or published, Dr. Moring shared this overview of the outcomes with us.
  • The average decrease in overall cholesterol was 13.37.
  • The average reduction in triglycerides was 24.57.
  • The average reduction in LDL (“bad”) cholesterol was 6.33.
  • The majority of participants (70%) experienced lower blood sugar.
  • Participants reduced their average blood-glucose level by 2.34 mg/dL, from slightly impaired to within normal limits.
  • An estimated ⅔ of patients had lower blood pressure after Whole30.
  • The average participant BMI decreased by 2.36 points, along with an average waist circumference reduction of 3.01 inches and an average weight loss of 12.11 pounds.
  • Dr. Moring reported that several participants in the study were able to reverse pre-diabetes. Several others with diabetes were able to reach blood-glucose targets. One participant was able to stop taking insulin by the end of their Whole30.
Other non-scale victories reported by Whole30 participants in Dr. Moring’s cohort study included improved digestion, clear skin, better sleep, fewer medications needed, more energy, less anxiety and depression, reduced pain, improved focus, better moods, and increased self-confidence. Along that same line, our internal data (unpublished) also showed that in 2022, a small focus group of Whole30 participants experienced a 13.4% increase in positive body perception on the clinically validated Body Appreciation Scale.

A food intolerance means someone has difficulty digesting or processing components (often a protein or sugar) within the food. An example of a common food intolerance is lactose intolerance; difficulty digesting the carbohydrate component of milk products. A food intolerance is usually caused by the lack of an enzyme needed to digest the food, but can also be caused by digestive diseases (like Irritable Bowel Syndrome).

With food sensitivities, an individual experiences an immune reaction after consuming specific foods, which can generate a multitude of symptoms (like joint pain, stomach pain, fatigue, rashes, and brain fog). With food sensitivities, the body’s response can happen after eating, but could also be delayed. This means you may not notice symptoms for up to three days after consuming the food. Food sensitivities have no standard medical definition and are sometimes referred to as food intolerance, IgG, or IgA response. Harvard Medical School* says the gold standard for identifying food sensitivities is a structured elimination and reintroduction protocol.

With a food allergy, your body’s immune system reacts to a food or a substance in the food, identifying it as potentially harmful and creating antibodies to fight it off. This response is known as an IgE and/or histamine response. It’s often immediate (within two hours after eating the food) and can be life-threatening, like in the case of peanuts causing anaphylaxis. Individuals should work with their healthcare provider if they suspect or are currently navigating a food allergy.

*Source: Health Harvard Publishing – Harvard Medical School

You may have heard friends or family members talk about a “food sensitivity” test they did at home or with their provider. For some, this test can provide helpful direction towards customizing their elimination diet protocol. For others, it can do more harm than good. In fact, organizations including the American Academy of Allergy, Asthma and Immunology, and the Canadian Society of Allergy and Clinical Immunology have recommended against using IgG testing to diagnose food intolerances and sensitivities.

IgG-based food sensitivity tests have not been proven to identify food sensitivities, and often have false positives. Intestinal permeability or frequent exposures to a food can result in multiple foods being erroneously flagged as “culprits” (foods to which you’re sensitive). This can result in unnecessary and sometimes excessive restrictions. In addition, these tests can be expensive, and therefore aren’t accessible to all. By contrast, elimination protocols, like the Whole30, offer a free, clear, and effective way to assess which foods may be contributing to symptoms in your body. Read this article by Dr. Caroline Arreola for more.

The opinions and/or information presented in this article is in no way intended as medical advice or as a substitute for medical treatment, and should only be used in conjunction with the guidance, care, and approval of your physician. Nothing herein is intended to diagnose, treat, cure or prevent any disease. Always consult a qualified healthcare practitioner before making any dietary or lifestyle changes.