What to Expect When Starting Paleo: A Beginner's Guide

December 26, 2025 •

4 min read

According to a 2021 review of studies, short-term adherence to a Paleolithic diet has been shown to result in weight loss, decreased waist circumference, and lower blood pressure. When you first start, the transition can be challenging, but understanding what's ahead can help smooth the path and make the process more manageable.

Quick Summary

A guide covering the initial weeks of starting a paleo diet, including potential side effects like the 'paleo flu', essential food swaps, meal planning tips, and the expected short- and long-term benefits.

Key Points

Initial Symptoms: Expect a 1-2 week adjustment period known as the 'paleo flu,' characterized by fatigue, headaches, and cravings, as your body switches from burning carbs to fat.
Food Focus: The core of the paleo diet is lean meat, fish, fruits, vegetables, nuts, and seeds; processed foods, grains, dairy, and legumes are excluded.
Meal Prep is Crucial: Prepare meals in advance to avoid relying on non-paleo processed foods, which are forbidden on the diet.
Hydration and Sleep: Drinking plenty of water and getting sufficient rest can help manage symptoms during the initial transition period.
Long-term Payoffs: Adherents often report benefits such as improved energy levels, better blood sugar control, and potential weight management after the initial adjustment.
Consider Cost and Nutrients: The diet can be expensive, and careful planning is needed to ensure adequate intake of nutrients like calcium and fiber, which are eliminated with grains and dairy.
Modified vs. Strict Paleo: Some people find a modified approach, which allows some dairy or legumes, to be more sustainable and beneficial for gut health in the long run.

The First Few Weeks: The 'Paleo Flu'

For many people, the initial phase of transitioning to paleo involves a period known as the 'paleo flu' or 'carb flu'. This occurs as your body, which is used to running on carbohydrates, adapts to using fat as its primary fuel source. Symptoms can feel a lot like a mild flu, but are temporary and manageable. It's not a true illness, but rather your body's reaction to carbohydrate withdrawal.

Common Symptoms of the 'Paleo Flu'

Headaches
Fatigue and low energy levels
Irritability and mood swings
Brain fog or difficulty concentrating
Sugar cravings
Digestive issues, such as diarrhea or constipation

This adjustment period typically lasts a few days to a couple of weeks, but varies widely from person to person. Hydration, sufficient rest, and eating enough healthy fats can help ease the symptoms. It's crucial to listen to your body and be patient during this phase, as the benefits often emerge once the initial adjustment is complete.

What to Eat and What to Avoid

Transitioning to paleo requires a significant shift in your pantry and meal planning. The diet focuses on whole, unprocessed foods that were available to hunter-gatherers, while eliminating modern foods introduced by agriculture and industrial processing.

Paleo-Friendly Foods

Lean meats and poultry: Grass-fed beef, chicken, turkey, and pork.
Fish and seafood: Wild-caught options rich in omega-3s like salmon and mackerel.
Fruits and vegetables: A wide variety of fruits and non-starchy vegetables.
Nuts and seeds: Walnuts, almonds, sunflower seeds, chia seeds.
Healthy fats: Avocado, olive oil, and coconut oil.
Eggs: A staple of the diet, from free-range chickens.

Foods to Avoid

Grains: Wheat, oats, rice, and barley.
Legumes: Beans, lentils, peanuts, and peas.
Dairy: Milk, cheese, and yogurt.
Refined sugar and sweeteners: Soda, candy, and processed desserts.
Processed foods: Anything packaged with artificial ingredients.
Certain oils: Canola oil, soybean oil, and other vegetable oils.

Practical Tips for Your Paleo Start

Ease into the transition by starting with small, manageable changes. Attempting to go 'cold turkey' can lead to more severe carb withdrawal symptoms and a higher chance of giving up.

Gradual Transition: Try a gradual approach. For example, eliminate grains and processed snacks for the first week, then tackle dairy and legumes in the following weeks.
Master Meal Prep: Planning and preparing your meals ahead of time is critical. Since processed, ready-made meals are off-limits, having pre-chopped vegetables or cooked protein on hand will prevent last-minute, non-paleo choices.
Smart Snacking: Prepare paleo-friendly snacks like nuts, seeds, or apple slices with almond butter to manage cravings and avoid reaching for convenience foods.
Stay Hydrated: Drink plenty of water throughout the day. Dehydration can worsen 'paleo flu' symptoms like headaches.
Focus on Fiber: With grains and legumes gone, you need to be intentional about getting fiber from fruits, vegetables, nuts, and seeds to support good gut health.

Paleo vs. Keto: Understanding the Differences

While both diets reduce carbohydrates, the underlying philosophy and specific rules differ significantly. The following table highlights the key distinctions:


Feature	Paleo Diet	Keto Diet
Primary Goal	Mimic ancestral eating for overall health.	Induce ketosis for fat-burning.
Macronutrient Focus	Focuses on whole foods, no strict macros.	High fat, moderate protein, very low carb.
Allowed Carbohydrates	Whole-food carbs like fruits and starchy vegetables are allowed.	Extremely limited carb intake; starchy veggies are restricted.
Dairy	Excludes all dairy, as it was unavailable ancestrally.	Allows high-fat dairy like butter and cheese.
Legumes	Excludes legumes based on the 'ancestral' model.	Excludes legumes due to carbohydrate content.
Sweeteners	Minimal natural sweeteners like honey are sometimes allowed.	Non-carb sweeteners only, like stevia.

Potential Long-Term Benefits and Challenges

Beyond the initial hurdles, consistent adherence to a paleo lifestyle can lead to several potential long-term benefits. These are often a result of focusing on nutrient-dense foods and eliminating processed, sugary items.

Long-Term Benefits

Weight Management: Increased satiety from protein and healthy fats can naturally lead to weight loss.
Improved Blood Sugar Control: Reduced intake of refined carbs can improve glucose tolerance and insulin sensitivity, potentially benefiting those with or at risk for type 2 diabetes.
Reduced Inflammation: Cutting out processed foods and vegetable oils may lower overall inflammation levels in the body.
Better Digestion: Many people report reduced bloating and improved digestion, though some may experience issues if fiber intake is not carefully managed.
Increased Energy Levels: Stable blood sugar levels from avoiding simple carbohydrates can lead to more consistent energy throughout the day.

Potential Challenges

Cost: Quality, grass-fed meat and organic produce can be more expensive than conventional options.
Nutrient Deficiencies: Without careful planning, eliminating dairy and grains can lead to low intake of calcium, vitamin D, and fiber. You may need to incorporate supplements or specific paleo-friendly sources like bone-in sardines for calcium.
Social Hurdles: Navigating social events and eating out can be difficult, as many restaurants don't offer strictly paleo options.
Long-Term Adherence: The restrictive nature of the diet can be difficult to maintain for some, with studies showing low long-term retention rates.

Conclusion: A Thoughtful Approach is Key

Starting paleo is a significant dietary change that involves a short-term adjustment period often accompanied by the 'paleo flu.' Success lies in understanding the fundamentals of the diet—eating whole, unprocessed foods while avoiding grains, legumes, and dairy—and being proactive about meal planning and potential nutrient shortfalls. While a thoughtful transition can help minimize side effects and lead to potential health benefits like weight management and improved blood sugar, it is not without its challenges, including cost and social pressures. Ultimately, the best approach is to start with a flexible mindset, listen to your body, and focus on sustainable, long-term healthy eating habits, whether strictly paleo or a modified version that fits your lifestyle. For additional resources and scientific context on the diet, readers can explore studies from authoritative sources like the National Institutes of Health.

Frequently Asked Questions

The 'paleo flu' is a common term for the temporary side effects some people experience when first starting paleo, including headaches, fatigue, and irritability, as the body adapts to a low-carb intake. It typically lasts from a few days to a couple of weeks.

No, the paleo diet is not a no-carb diet. It emphasizes avoiding refined and processed carbs like grains and sugar, but allows for carbohydrates from whole foods like fruits, vegetables, nuts, and seeds.

It can be. A diet that emphasizes grass-fed meat and organic produce can be more costly than one that includes grains and legumes, which are often more affordable staples.

Paleo-friendly snack options include nuts, seeds, fresh fruit, cut vegetables like carrot sticks or celery, and hard-boiled eggs.

Short-term studies show that the paleo diet can lead to weight loss and a reduction in waist circumference. Many people find that focusing on whole foods and high protein/fat intake naturally helps with weight management by increasing satiety.

Some health experts raise concerns about potential nutrient deficiencies, particularly calcium and vitamin D due to the elimination of dairy. The long-term effects of paleo are not as extensively studied as other dietary patterns, so careful planning and potential supplementation are necessary.

The biggest difference is the approach to carbohydrates. While both restrict them, keto is a very low-carb, high-fat diet with a goal of achieving ketosis. Paleo is a whole-foods diet that is not necessarily low-carb and does not track macronutrients.

Most strict paleo versions permit minimal use of natural sweeteners like honey or maple syrup, as they would have been available to ancestors. However, some prefer to avoid all forms of sugar to kick cravings.

Without dairy, calcium can be obtained from dark leafy greens, bone-in fish like sardines or salmon, and seeds. Some people may also consider supplementation, but should consult a healthcare professional.