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How Gut-Friendly Are the Newest Diet Trends?

Written by Dr. Ruscio on November 8, 2022

Written by Dr. Ruscio on November 8, 2022 — Reviewed by Hannah Hamlin

• Key Principles of a Gut Healthy Diet|
• Paleo Diet|
• Low FODMAP|
• Intermittent Fasting|
• Mediterranean Diet|
• Keto Diet|
• DASH Diet|
• Eat Like a Bear Diet|
• E2M Diet|
• Carnivore Diet|
• Bottom Line on Trendy Diets|

When you think there can’t possibly be another new diet to come along, another one pops up on Instagram or TikTok.

In this article, we’ll take a look at some of the newest diet trends, as well as a few of the more established ones, and score them from the perspective of gut health.

The italics are important here because if you have a healthy microbiome and no significant digestive issues, our score sheet may not apply to you. However, if you are dealing with irritable bowel syndrome, bacterial overgrowth, or general symptoms like constipation, bloating, and/or abdominal pain, you’ve come to the right place.

You shouldn’t be concerned if the diet that works for you isn’t one we rate highly as everyone is different and what suits one person may not suit another. Our ratings are scientifically and clinically backed, but they may not align perfectly with your experience. It’s important not to get too caught up in the ratings, and use this as a general, introductory diet guide for your gut health. 

To reiterate, we’re honing in on diets and the newest diet trends that generally seem to be better for people with gut sensitivity, gut dysbiosis, SIBO, IBS, and the like. If you have other health goals or are interested in these diets in greater detail, stay tuned for our ‘Diets Debunked’ series where we break down these diets to see what other health benefits they can offer you.

Key Principles of a Gut-Healthy Diet

First it’s important to explain the yardstick we’ll be using to measure the newest diet trends against. In our clinical practice at The Ruscio Institute, we’ve found that four basic principles underpin virtually all successful gut-healing diets.

These principles are:

• Eat to quell inflammation. This means eating only a very minimal amount of ultra-processed foods, sugars, sweeteners, and other additives. Whole foods like lean, unprocessed meats, oily fish, nuts, green vegetables, and fruits are the ones to eat more of.
• Find the level of carbs and prebiotics that works for you. Gut microbial imbalances can mean that eating too many carbs, even the “good” sort in fiber-rich foods, may trigger uncomfortable gut symptoms. Prebiotics (fibers such as inulin that stimulate gut bacterial growth) are often touted as a cure for gut issues, but caution is needed as some people are sensitive to fiber [1]. Further along in your gut health journey prebiotics may help to keep your gut bacteria in good shape but when you are still very symptomatic, it’s best to go easy.
• Eat to control blood sugar. High blood sugar levels can negatively influence the microbiota so eating to control your blood sugar will benefit your gut [2]. Minimizing spikes in your blood sugar and insulin levels also has many other benefits, with lower-glycemic diets (lower in fast-releasing carbs like mashed potatoes, white bread, and sweets) being linked with reduced risks for cancer, heart disease, and obesity [3]. 
• Identify your food allergies and intolerances. People who have gut disturbances will often have a problem tolerating some foods (this can be temporary or, less often, permanent). Diets that allow you to experiment with which foods may or may not suit you can be helpful in getting your gut health back on track.

Now that we’ve laid out the parameters by which we’ll measure the gut healthiness of each of the newest diet trends, it’s time to look at how they stack up.

Diet Trends: The Paleo Diet

What is It?

Compared with a modern westernized diet, the Paleo diet is closer to what our ancestors probably ate during the stone age (Paleolithic era). The idea is that this diet may be more or biologically appropriate for humans and, therefore, better for our health.

Pros

The Paleo Diet calms inflammation by minimizing your exposure to foods that provoke an immune response [4, 5] a great choice for helping to balance blood sugar [6, 7]

You also don’t eat problematic foods like gluten, dairy, and soy, which can reduce the burden of gut symptoms. 

A few studies showed the Paleo diet to be effective for weight loss and reducing waist size [8, 9, 10], though probably not more effective than other dietary approaches after two years [11].

Small studies also suggest that the Paleo diet is effective for improving [8]: 

• Triglycerides and HDL cholesterol 
• Blood pressure, although the difference here was small 
• Blood sugar

Cons

Critics of Paleo suggest that versions of the diet that are too heavily meat-based (not fish-based) are too high in saturated fats, and eliminating dairy may affect vitamin D and calcium levels. Without enough leafy greens like kale, collard greens, and spinach, low calcium is even more of a concern.

Gut Health Rating ⭐⭐⭐⭐½

A Paleo framework may be good for:

• Mild-to-moderate food sensitivities
• Mild bacterial imbalances
• Low-grade gut inflammation
• Blood sugar imbalances

If you approach this diet flexibly, it’s enjoyable and not too restrictive while enabling you to determine what levels of carbohydrates and prebiotics you can personally tolerate. 

That said, for people with more extreme gut issues, Paleo may not offer enough symptom relief. They may require a deeper dive into their food triggers (e.g. the low FODMAP diet). Another option that can deliver greater benefit for some is combining Paleo with intermittent fasting. 

Diet Trends: Low FODMAP Diet

What is It?

The low FODMAP diet identifies the carbs and prebiotics that you may be sensitive to. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols, which are the different types of fermentable starches and sugars that can cause bloating and trigger irritable bowel syndrome (IBS) symptoms.

The most important tool for using the low FODMAP diet is a good FODMAP food list. 

Pros

For many people with gut sensitivities and/or bacterial overgrowth (like SIBO), the low FODMAP diet can be a game changer.

For example, two meta-analyses determined that the low FODMAP diet reduced overall digestive symptoms and abdominal pain, and increased quality of life [12, 13].

Other research shows that the low FODMAP diet:

• Improves diarrhea in IBS-D [14]
• Improves IBS symptoms in patients with inflammatory bowel syndrome (IBD) [15, 16, 17, 18]
• Positively impacts gut endocrine cells, which can normalize bowel function [19, 20, 21]
• Reduced pain for fibromyalgia patients [22]

Cons

The low FODMAP diet is highly restrictive and can be a hassle that makes food shopping, eating out, and cooking quite tricky. If you don’t have a particularly sensitive gut, or more mild digestive symptoms, the low FODMAP diet may not be worth the work involved. This is why we often don’t recommend jumping straight into a low FODMAP diet before trying other elimination diets. Reintroducing foods after the initial elimination period can also be time-consuming and difficult without professional help.

Gut Healthy Rating ⭐⭐⭐⭐⭐

A low FODMAP diet may be good for:

• Moderate to severe GI symptoms and/or sensitivities
• Carbohydrate and prebiotic intolerances
• Small intestine bacterial overgrowth (SIBO)
• IBS and inflammatory bowel disease (IBD)
• Symptoms that have failed to respond to a less-restrictive diet

The low FODMAP diet gets a top score for gut healthiness because of the solid research (outlined above) that it can improve symptoms of IBS, inflammatory bowel disease, fibromyalgia, and more. Despite its high level of food restriction, clinically, we also find the low FODMAP diet to be one of the most effective diets for reducing many symptoms.

Diet Trends: Intermittent Fasting

What is It?

While it may be thought of as one of the newest diet trends, intermittent fasting has actually been around for centuries. The latest versions include time-restricted eating (when you restrict your eating to a small time window each day), the twice-a-week (5:2) method, and alternate-day fasting [23].

Pros 

Intermittent fasting may benefit many people, especially those seeking to improve their obesity, type 2 diabetes, high blood pressure, heart disease, general inflammation, gut health, and fitness [24].

Specific gut-related benefits include:

• Better gut microbes [25, 26, 27, 28, 29] 
• Better gut hormones [30] 
• Better gut wall integrity [31, 32, 33]
• Fewer IBS symptoms [32]

Other researched health benefits of this eating pattern include: 

• Metabolic health, heart health, and weight loss [34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47] 
• Fitness and athletic performance [48, 49, 50, 51, 52, 53]
• Reduced inflammation [54]
• Liver health [55]
• Cognitive health [56]

Cons

The longer-term effects of intermittent fasting aren’t yet well known. It’s also not for everyone, and people who are very young, pregnant, breastfeeding, immunocompromised, or have eating disorders should also avoid it [24, 57].

Possible fasting side effects include low blood sugar, dizziness, weakness, and muscle wasting [24]. Older people must include enough protein in eating windows to avoid muscle wasting [24].

Gut Health Rating ⭐⭐⭐⭐

Intermittent fasting may be good for:

• Low-grade intestinal inflammation
• Leaky-gut syndrome
• Irritable bowel syndrome
• Gut bacterial imbalances (like SIBO)
• Giving your gut a rest and chance to heal

As outlined above, intermittent fasting has some significant gut health benefits, which may be to do with allowing your digestive system downtime and not constantly flooding your system with glucose. 

However, there’s nothing magical about intermittent fasting that protects you from food sensitivities. You can still experience symptoms if your diet includes personal trigger foods, so it’s important to focus on the anti-inflammatory quality of your food during your eating window.

Diet Trends: The Mediterranean Diet

What is It?

The Mediterranean diet is a dietary pattern that emphasizes high intake of extra virgin olive oil, vegetables (especially green leafy vegetables), fruits, cereals (whole grains), nuts, pulses, and legumes, with a moderate intake of fish and other meat, dairy products and red wine, and low intakes of eggs and sweets [58].

Pros

A Mediterranean diet has been shown to be one of the best diets for health-related quality of life in both adults and young people [59, 60]. Specifically, it has been linked with: 

• Cognitive benefits [61, 62, 63]
• Lower incidence of cardiovascular disease and death from cardiovascular disease [64] 
• Lower incidence of type 2 diabetes [64]
• Lower incidence of cancer and death from cancer [64]
• Reduced disease activity and fatigue in those with rheumatoid arthritis [24, 13]
• Meaningful improvements in markers of inflammation in the body [65]

One year-long study looked at how the Mediterranean diet affected the microbiome in elderly people. It found encouraging upticks in types of bacteria associated with reduced frailty and better cognitive function [66]

Cons

There aren’t any notable health risks associated with the Mediterranean diet. But if you’re struggling with poor gut health it might not work for you. It includes dairy, gluten, nightshades (bell pepper, eggplants, tomato, etc.), and fermentable fibers, which can all be irritants to a highly sensitive gut [59]. 

Gut Health Rating ⭐⭐⭐½ 

The Mediterranean diet may be good for:

• Low-grade gut inflammation
• Those wanting a non-restrictive, gut-healthy diet
• Mild food sensitivities
• Blood sugar imbalances

While research supports the benefits of a Mediterranean diet on gut health, this should be balanced against our clinical experience which finds that the diversity of foods, particularly carbs and fibers in the Mediterranean diet can be more than some people with a sensitive gut can handle.

Diet Trends: The Keto Diet

What is It?

A keto (ketogenic diet)  is a popular diet with very low carbohydrate, high fat, and moderate protein intake. On a keto diet, you will get approximately 5–10% dietary energy from carbohydrates — for reference, a 2,000-calorie-per-day diet contains about 20–50 grams of carbohydrates per day on the keto diet [67].

When carbohydrate intake is restricted and glucose levels become very low, the body goes into ketosis — i.e. starts producing ketones to replace glucose as the primary source of energy. Ketosis is proposed to have many different health benefits for various organs.

Pros

In my experience, low carbohydrate and low prebiotic diets are helpful for certain gut conditions, like IBS. This may be due to the alterations that these diets, including keto, have on the gut microbiome and inflammation levels. 

However, it’s unclear if these shifts in the gut flora have direct health benefits, and the answer may not be so straightforward. Changes in the microbiome that are unfavorable for gut health, may be the same alterations that benefit the nervous system [68, 69].

Overweight individuals with metabolic syndrome, insulin resistance, and high blood sugar are likely to benefit from a well-formulated ketogenic diet [67].

Keto diets have also shown promise for: 

• Neurological diseases including Alzheimer’s (in fact the keto diet was originally a medical diet for reducing seizures in children). The ketones produced when you consume a keto diet have anti-inflammatory properties and may protect the brain [70]. 
• Other neurological conditions such as epilepsy, dementia, ALS, and traumatic brain injury [67].

Keto may have an overall beneficial effect on lipids, as HDL cholesterol and triglycerides can improve on the keto diet [67, 71]. 

Cons

The keto diet is restrictive, which can make it difficult to stick to. When you first start out, some of the temporary side effects (like headache, constipation, fatigue), known as the “keto flu,” can also be off-putting. The long-term effects of keto on health are also not well known [67].

Some reviews suggest that the effects on the microbiome may not always be beneficial, as ketogenic diets with minimal fiber may reduce microbial diversity and the production of beneficial short-chain fatty acids like butyrate [72, 73, 68]. Keto may also increase the growth of pathogenic bacteria and have a pro-inflammatory effect in the gut [69, 74].

However, studies suggest that these effects can be mitigated by using probiotics while eating a keto diet [74].

Despite the above, beneficial effects on lipids, one study found that women following a low-fiber ketogenic diet (low-carb, high-fat) had much higher levels of LDL cholesterol than those eating a normal-fiber diet [75]. This could be a particular concern if you already have a high heart disease risk; however, higher fiber keto diets are possible if you include non-starchy veggies, nuts, and seeds. 

Gut Health Rating ⭐⭐½

The ketogenic diet may be good for:

• Carbohydrate and prebiotic intolerances
• Small intestine bacterial overgrowth (SIBO)
• Low-grade gut inflammation

While there’s still much to learn about the effects of a keto diet on digestive health, clinically it delivers good results for many patients with multiple gut sensitivities. This is likely because of the elimination of excess carbs and prebiotic fibers that can cause bacterial overgrowth. 

Overall, the effects of the keto diet on the microbiome are unclear and demonstrate more generally that what happens to specific populations of bacteria in your gut is less important than achieving symptomatic relief. However, it’s suggested that keto may lower gut inflammation [69], so your gut can become the right environment for healthier bacteria to grow long-term.

Diet Trends: The DASH Diet

What is It?

DASH stands for Dietary Approaches to Stop Hypertension. The diet aims to reduce high blood pressure by promoting increased consumption of minimally processed and fresh vegetables and fruits, lean meats, and dairy, and reduced consumption of sodium. It’s also a high-fiber diet.

Pros

While there are few gut-specific benefits of the DASH diet, its focus on nutrient-dense and overall anti-inflammatory foods likely deliver similar benefits to the Mediterranean diet. Some research suggests that DASH could also reduce the risk of colorectal cancer in men (but not women) [76]. 

A 2020 comprehensive review showed that the DASH diet significantly reduced both systolic and diastolic blood pressure compared to control diets [77].

DASH also has proven benefits for people with type 2 diabetes, high cholesterol, high triglycerides, overweight, and heart failure [78].

Other studies have shown the DASH diet is helpful for people with [78]:

• Chronic liver disease, 
• Diverticular disease, 
• Weight loss goals

Cons

A 2019 randomized controlled trial (RCT) found that the DASH diet significantly increased bloating compared to a lower fiber diet [79]. The increased bloating was likely related to increased fiber intake. While fiber can be beneficial for certain gut conditions, like chronic constipation, it may provoke symptoms in some who have IBS, IBD, or SIBO.

Gut Health Rating ⭐⭐⭐ 

The DASH diet may be good for:

• Those wanting a non-restrictive, gut-healthy diet
• Mild food sensitivities
• Blood sugar imbalances
• Diverticulosis or colon cancer (potentially)

Overall the DASH diet is fairly balanced and high in vegetables and low in processed foods. While it would get a higher star rating for general health, it has to be rated lower when considering people with gut sensitivities. Specifically, its high fiber content can be an issue for people with irritable bowel syndrome. It is also not a viable choice for those with gluten and dairy intolerance.

Diet Trends: “Eat Like a Bear” Diet

What is It?

The premise of the eating plan is that you combine keto or low-carb with intermittent fasting to lose weight. In practical terms, it generally involves eating a huge salad topped with protein as your main or only meal each day. The “Eat Like a Bear” name comes from consuming food during a short window of time during the day, analogous to a bear feasting and then going into hibernation mode. The framework of the diet is taught in a three-day challenge [80]. 

Pros

Individually, the keto and intermittent fasting diets have some decent research backing (see above) their effects on gut health, which may extend to the Eat Like a Bear diet. However, there is no direct research on the digestive benefits of this diet trend.

Due to the significant calorie restriction, weight loss is very likely if that is what you were hoping for.

Cons

Both of the potential downsides of intermittent fasting and low carb will apply to this newest diet trend. The diet is quite vague if you don’t opt for the paid-for content. Since it could be quite restrictive, there’s also a risk of nutrient deficiencies if you’re not consuming nutritious foods during the feeding window.

Gut Health Rating ⭐⭐½

The “Eat Like a Bear” diet may be good for:

• Combined benefits of intermittent fasting and low-carb diets

It’s hard to rate the Eat Like a Bear diet for gut health because it depends greatly on how you interpret it and the version you do. On one hand, it incorporates principles of intermittent fasting, which is generally good for gut health and appears to focus a lot on whole unprocessed foods (generally a plus for gut health). However, there is no specific emphasis on finding and eliminating troublesome foods for people with gut issues. 

Until we know more about this diet, sticking to traditional intermittent fasting is probably best, and can be combined with Paleo for additional gut-health benefits. 

Diet Trends: The E2M Diet

What is It?

E2M stands for “eager to motivate” and involves exercise and diet to lose weight. It was created by Jeff Witherspoon, an army veteran [81].

The 8-week program includes weekly workout plans and meal plans. The program costs $320, spread out over 8 payments of $40. The core principles include intermittent fasting, low carb levels (with some higher carb days), no dairy, and 6 workouts, with a focus on strength, a week.

Pros 

Because you avoid processed foods, refined sugars, and alcohol this is likely to be good for stabilizing your blood sugar levels and lowering gut inflammation.

The program includes recorded live workouts, motivational talks, and online support, so you’re supported to trim down and get stronger. It is the only diet on this list that contains such a comprehensive health plan. 

Cons

E2M takes quite a lot of dedication and the claims of increased energy levels, reduced inflammation, and improved metabolism haven’t been tested in clinical studies. Additionally, content has to be purchased to be accessed, which limits the transparency of the diet and creates a financial barrier for some.

Gut Health Rating ⭐⭐½

The E2M diet may be good for:

• Those wanting a non-restrictive, gut-healthy diet
• Mild food sensitivities
• Blood sugar imbalances
• Those who prefer outside support to meet their health goals

In many ways this diet is quite similar to a Paleo framework and the fact that it cuts out or minimizes dairy and grain — two of the common culprits when it comes to food intolerances — may help people experiencing gut symptoms. However, it’s not specifically focused on improving gut health and we have too little in-depth knowledge of it to give it more than a medium gut health rating. 

If you are interested in diet alone, and are okay to skip the motivation and personal training, Paleo is likely your best bet.

Diet Trends: The Carnivore Diet

What is It?

Ketogenic in nature, the carnivore diet is one of the newest eating trends and an extreme way of eating. It involves the consumption of only animal products, including eggs and dairy. All or almost all plant foods are eliminated [82]. 

Pros

There are no clinical trials assessing the effects of the carnivore diet. However, a 2021 observational study revealed over half of carnivore diet adherents claimed to have better [83]:

• Energy
• Sleep
• Mental clarity
• Psychological health
• Strength/endurance 

Cons

The same study found that a small minority of people on a carnivore diet experienced 

• Markedly elevated LDL and total cholesterol
• Skin issues
• Muscle cramps
• Constipation 
• Insomnia
• Dizziness
• Menstrual irregularities
• Kidney stones
• Poor wound healing

Meat doesn’t provide sufficient amounts of certain nutrients such as calcium and vitamin C, and a lack of plant foods means you miss out on fiber and phytochemicals that are linked with beneficial effects on health [82, 83]. The International Agency for Research on Cancer has also classified processed red meat as potentially cancer-causing [84].

Gut Health Rating ⭐

The carnivore diet may be good for:

• Extreme sensitivities to plant-based foods and grains
• Temporary use only 

Getting no plant fiber is the biggest potential issue of the carnivore diet for long-term gut health. It may contribute to constipation and change the makeup of your gut microbiota. We don’t have any long-term research to say if this will contribute to bigger problems, but in theory, it might. This is why we’re going to give the carnivore diet a low rating for gut healthiness while awaiting further data. 

That said, I know patients who switched to a full-carnivore diet due to really extreme sensitivities to plant foods. For these people, it does seem to bring symptom relief in around 60% of cases. However, moving forward I encourage them to get a more varied diet, such as the Paleo or Mediterranean diet. You can learn more about the Carnivore diet in this podcast.

The Bottom Line on Diet Trends

Of the new diet trends we’ve looked at, the Carnivore diet, E2M diet and Eat Like a Bear Diet are either not so great for long-term gut health or have too little information to assess. 

Intermittent fasting stands up well as a suitable choice for people with minor to moderate gut issues. However, a Paleo-style diet is probably the easiest place to start for helping to get your gut back in shape, while the low FODMAP diet is the most trusted option for more severe symptoms.

Others like DASH are nutritious and have lots going for them health-wise in general but might not be so good for a sensitive gut. The Mediterranean diet is a healthy longer-term choice for people who have less significant gut symptoms.

But as stated above, our guide may not perfectly align with your needs or personal experience. Always be sure to go with what feels right for you.

Healthy Gut, Healthy You investigates some of these diets in more depth and presents them in the context of an eight-step plan for rebuilding your gut health. 

If you’d prefer a one to one consultation advice from a highly experienced functional health practitioner on any gut health issues, this is also available.

The Ruscio Institute has also developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.