The paleo diet, often referred to as the caveman diet, aims to emulate the eating habits of our ancestors from the Paleolithic era, which occurred approximately 2.5 million years ago. While the dietary habits of prehistoric humans varied across different geographic regions, they typically enjoyed a rich array of protein sources such as insects, wild game, and seafood, complemented by a diverse selection of plants including fruits, tubers, nuts (e.g., akhrot), and seeds.

In today's world, where our food systems have undergone significant changes, the contemporary paleo diet emphasizes the importance of consuming whole, minimally-processed foods. Adherents of the paleo lifestyle tend to avoid grains, dairy products, most forms of added sugars, legumes, and certain oils, particularly canola oil.

When followed correctly, a balanced paleo diet can be a nutritious choice and may enhance various aspects of health. However, if not meticulously planned, it can lead to a range of adverse effects.

Below are four potential side effects associated with the paleo diet.

1. Diarrhea

Many individuals do not meet their daily fiber requirements. In fact, most adults in various countries, including the United States, typically consume around 15 grams of fiber each day, which falls short of the recommended intake. Nutrition experts recommend that women under 50 should aim for about 25 grams daily, while men under 50 should target approximately 38 grams.

This deficiency in fiber is largely due to contemporary diets that are predominantly composed of ultra-processed foods, lacking in essential fiber-rich options, such as fruits and vegetables. Adopting a paleo diet, which is abundant in fiber-rich plant-based foods, including various vegetables, fruits, and nuts, may lead to digestive changes for individuals transitioning from a low-fiber diet to this more fiber-dense option.

When someone shifts to a higher fiber intake, particularly through a well-structured paleo diet, they might experience diarrhea, especially if they are not accustomed to incorporating fiber-rich foods like fruits, vegetables, nuts, and seeds into their meals. This reaction occurs because foods high in insoluble fiber can function as natural laxatives, potentially resulting in diarrhea.

Moreover, for specific populations, such as those dealing with irritable bowel syndrome (IBS)i, a higher fat diet like the paleo regimen might exacerbate digestive issues, including diarrhea. Research supports this notion; a study indicated that participants consuming a paleo diet had an increased incidence of diarrhea. In this investigation, 39 healthy women adhered to either a paleo diet or a balanced diet that included grains and dairy over a four-week period.

The findings revealed that women on the paleo diet experienced significantly higher instances of diarrhea compared to those on the general diet. Hence, transitioning to higher fiber diets, particularly those that are well-structured, such as paleo diets, may lead to digestive discomfort in individuals unaccustomed to high-fiber foods like fruits, vegetables, nuts, and seeds.

2. Constipation

Many individuals perceive the paleo diet as merely a low carbohydrate plan that emphasizes high animal protein intake, yet this perception is somewhat misleading. While the paleo diet eliminates typical carbohydrate sources, such as grains, snack foods rich in carbs, and added sugars, it balances this by being abundant in fiber-rich foods including a variety of vegetables, fruits, nuts (like akhrot in India), and seeds.

For those adhering to a paleo diet that is extremely low in carbohydrates but lacks sufficient fiber from these whole food sources, the risk of experiencing constipation increases significantly. Transitioning from a high carbohydrate, plant-based regimen to a low carb, paleo-inspired diet may drastically lower one's fiber consumption, which can adversely affect digestive health.

Fiber is crucial as it adds bulk to the stool, promoting its smooth movement through the digestive system. Insufficient fiber intake can result in constipation, which not only causes discomfort but can also have detrimental effects on overall health.

To avoid such issues while following a paleo diet, it is vital to incorporate an ample amount of fruits, vegetables, nuts, and seeds into daily meals. Hence, if your paleo approach minimizes the consumption of fiber-rich foods like fruits, vegetables, nuts, and other paleo-compliant sources, the likelihood of constipation can increase.

3. Changes in Gut Bacteria

Recent research indicates that individuals adhering to a paleo diet over an extended period may encounter detrimental alterations in their gut microbiome. A particular study monitored 44 participants strictly following either a paleo or a modified paleo diet, alongside 47 individuals on conventional diets for a minimum duration of one year.

The results revealed that those on the paleo diet exhibited diminished levels of certain advantageous bacterial strains while experiencing an increase in harmful Hungatella bacteria. Elevated levels of these bacteria may pose risks due to a compound they produce known as trimethylamine (TMA). Specific gut bacteria, such as Hungatella, generate TMA by metabolizing compounds prevalent in red meat, eggs, and dairy products. This TMA is subsequently converted into trimethylamine N-oxide (TMAO).

Moreover, the findings highlighted that individuals on strict or modified paleo diets had a noticeably lower intake of resistant starch. This particular type of starch, when fermented by gut bacteria, produces beneficial compounds known as short-chain fatty acids (SCFAs).

SCFAs serve as a crucial energy source for the cells lining the colon and play significant roles in numerous health aspects. Given these insights, researchers have raised concerns that a long-term diet that entirely excludes grains and legumes may not promote optimal gut health.

Nonetheless, additional research is essential to comprehensively understand the impact of the paleo diet on gut health. Some studies suggest that a long-term commitment to a paleo diet may adversely affect gut health by diminishing beneficial bacteria populations while increasing TMA-producing Hungatella bacteria.

4. Fatigue

A diet that is not well thought out can leave you feeling out of sorts and significantly lower your energy levels.

If a paleo diet is overly restrictive, it may result in diminished energy and persistent feelings of exhaustion. Being overly restrictive implies that it lacks sufficient calories or essential nutrients, particularly carbohydrates.

Insufficient carbohydrate intake can be a major contributor to fatigue. Various low carbohydrate diets, such as the ketogenic approach, have been associated with feelings of tiredness. Studies indicate this fatigue may stem from diminished glycogen reserves, which can occur with a low carb regimen.

Glycogen serves as a vital energy reservoir stored in your muscles and liver, providing a quick source of fuel for your body.

It's important to note that the paleo diet is not intrinsically a low carb diet. You can enhance the carbohydrate content in a paleo diet by incorporating more paleo-friendly carbohydrate sources, such as sweet potatoes (shakarkandi), winter squash (sorakaya), and various fruits.

However, if a paleo diet fails to supply the energy and nutrients your body requires on a daily basis, you may find yourself grappling with fatigue.

An inadequately structured paleo diet lacking in essential calories or carbohydrates can adversely impact your energy levels.

How to Embrace a Healthy Paleo Diet

While some research indicates that the paleo diet might lead to a few side effects, the majority of studies suggest that it is generally well-accepted and does not correlate with negative health outcomes. Interestingly, one analysis indicated that the paleo diet may offer superior psychological benefits compared to other widely followed diets.

This particular study examined the psychological impacts of five distinct dietary patterns, including vegetarian, vegan, gluten-free, paleo, and weight loss diets. Results revealed that individuals adhering to paleo dietary principles reported the lowest frequencies of disordered eating behaviors, intense food cravings, emotional eating episodes, and negative feelings.

Additionally, the paleo diet may also positively impact various health parameters, including metabolic health. So, how can you maintain a balanced and nutritious paleo diet that minimizes the risk of adverse effects?

Here are several useful tips:

• Consider a modified paleo approach. This version is less stringent and permits a limited intake of grains, legumes (dal), and dairy products. Research indicates that a modified paleo diet could be more beneficial for gut health than its unmodified counterpart.
• Ensure adequate fiber consumption. It is common for individuals following a paleo diet to fall short on fiber intake. Incorporating a variety of vegetables, fruits, and fiber-rich foods like chia seeds and flaxseeds can significantly enhance your fiber levels.
• Prioritize regular, balanced meals. Eating consistent and nutritionally balanced meals tailored to your activity levels, body size, age, and weight management goals is crucial for maintaining energy, regulating blood sugar, and supporting digestion.
• Remember, the paleo diet isn't inherently low in carbohydrates. While the paleo diet can be structured as a low-carb eating plan, it also allows for increased consumption of fruits and starchy vegetables to elevate carbohydrate intake when necessary.
• Consult with a registered dietitian. If you're keen on adopting a paleo diet but are unsure where to begin, it might be beneficial to collaborate with a registered dietitian. They can assist you in crafting a paleo meal plan that meets your nutritional requirements and promotes your overall well-being.

Moreover, any dietary pattern — including unrestricted ones — can lead to low or inadequate nutrient intakes. Eliminating food groups such as legumes, all grains, and dairy might heighten the risk of underconsumption of specific nutrients. However, research suggests that paleo and modified paleo diets present minimal nutritional risks when compared to standard eating habits.

Additionally, certain nutrient deficiencies, like vitamin D deficiency, are prevalent regardless of dietary choices. In fact, vitamin D deficiency is among the most widespread nutrient shortfalls globally.

To mitigate the risk of side effects and nutrient deficiencies, focusing on regular, nutrient-dense, and balanced meals is essential. Incorporating fiber-rich foods and adopting a less restrictive modified paleo diet may also prove beneficial.

The Bottom Line

The paleo diet can indeed serve as a healthful dietary pattern for many individuals. However, akin to any restrictive eating regimen, it might result in certain side effects.

Research indicates that some individuals may encounter symptoms such as diarrhea, constipation, fatigue, and alterations in gut microbiota while adhering to a paleo dietary framework.

To reduce the likelihood of experiencing these unwelcome side effects and to ensure adequate nutritional intake, it is important to consume regular, balanced meals that encompass a wide array of nutritious foods that are compatible with a paleo lifestyle.