By Paleo Life Coach Editorial Team · Last updated September 25, 2026 · Reviewed against Harvard T.H. Chan diet reviews, official Whole30 rules and PubMed-indexed trials
You’ve narrowed it down to four: paleo, keto, Whole30 or the Mediterranean diet. Friends swear by each one, and every website seems to crown a different winner. The useful way to compare them is on three questions: what can you actually eat, what does a normal day look like in numbers, and how strong is the evidence behind each. This guide answers all three with a food matrix, USDA-computed sample days and the key study for each diet.
The quick version: Paleo is whole foods without grains, legumes or dairy and no carb limit. Keto keeps carbs under about 50 g a day to produce ketones and allows dairy. Whole30 is a strict 30-day paleo-style elimination with a reintroduction phase. The Mediterranean diet is the most flexible, built on vegetables, whole grains, legumes, olive oil and fish, and has the strongest long-term evidence.
How do paleo, keto, Whole30 and Mediterranean compare at a glance?
| Paleo | Keto | Whole30 | Mediterranean | |
|---|---|---|---|---|
| Core idea | Eat like a hunter-gatherer | Stay in ketosis | 30-day elimination, then reintroduce | Traditional eating pattern of Mediterranean countries |
| Length | Ongoing | Ongoing or cycled | 30 days + 10 or more days | Ongoing |
| Carbohydrate | Not limited (fruit, starchy vegetables) | Under 50 g/day, sometimes 20 g | Not limited (fruit, potatoes) | Moderate to high, from whole grains, legumes, fruit |
| Fat | Moderate to high | 70–80% of calories | Moderate to high | Moderate, mostly olive oil, nuts, fish |
| Tracking | No | Carb counting | No weighing or measuring yourself | No |
| Portion guidance | Not emphasized | Macro ratios | Not emphasized | Not specified by the pyramid |
| Best known for | Whole-food, grain-free eating | Rapid carb restriction; epilepsy therapy | Finding food sensitivities, breaking sugar habits | Heart-health evidence |
Sources: Harvard T.H. Chan diet reviews of the paleo, ketogenic and Mediterranean diets; Whole30 program rules.
Which foods are allowed on each diet?
This matrix is where the four diets really separate. “Limited” means allowed in small amounts or with conditions.
| Food | Paleo | Keto | Whole30 | Mediterranean |
|---|---|---|---|---|
| Meat, poultry, eggs | Yes | Yes | Yes | Yes; poultry and eggs moderate, red meat a few times a month |
| Fish and seafood | Yes | Yes | Yes | Yes, preferred protein, at least twice a week |
| Non-starchy vegetables | Yes | Yes | Yes | Yes, daily |
| Fruit | Yes | Limited (berries) | Yes | Yes, daily |
| Sweet potatoes, winter squash | Yes | No | Yes | Yes |
| White potatoes | Usually avoided | No | Yes (not chips or fries) | Yes |
| Whole grains (oats, brown rice, whole wheat) | No | No | No | Yes, daily |
| Beans, lentils, chickpeas | No | No | No (green beans and most peas allowed) | Yes, daily |
| Peanuts, peanut butter | No | No (a legume) | No | Yes |
| Cheese, yogurt | No | Hard cheeses yes; higher-lactose dairy restricted | No | Moderate |
| Butter | Gray area | Yes | No (ghee only) | Limited; olive oil replaces it |
| Olive oil | Yes | Yes | Yes | Yes, the primary fat |
| Nuts and seeds | Yes | Yes, in moderation | Yes | Yes |
| Honey, maple syrup | Small amounts | No | No | Small amounts |
| Wine | Discouraged | Limited (dry wine) | No | Moderate with meals |
| Paleo or keto baked treats | Allowed | Allowed if low-carb | No (Pancake Rule) | Not applicable |
Sources: Harvard T.H. Chan diet reviews linked above; the Harvard Mediterranean review describes daily whole grains, legumes, fruit, vegetables, nuts and olive oil, fish at least twice weekly, red meat a few times a month and moderate wine with meals. Whole30 column from the official rules.
Whole30 and paleo agree on almost every row; the differences are sweeteners, treats, alcohol and a few exceptions. For those details see paleo vs Whole30. Keto and Mediterranean are near-opposites on grains, legumes and fruit.
What does a day of eating look like on each diet?
We built one sample day for each diet at a similar calorie level and totaled it with USDA FoodData Central values. The paleo day also passes Whole30 rules.
| Paleo / Whole30 | Keto | Mediterranean | |
|---|---|---|---|
| Breakfast | 3-egg omelet with spinach and pepper; strawberries; banana | 3 eggs with spinach, 1 oz cheddar, butter | Plain nonfat Greek yogurt, 1 cup blueberries, walnuts |
| Lunch | Chicken salad with avocado and olive oil | Salmon on romaine with olive oil and 1/2 avocado | Black beans and rice with onion; big salad with olive oil |
| Dinner | Salmon, broccoli, sweet potato | 85% ground beef, broccoli, butter, 2 tbsp cream | Salmon, broccoli, 1 cup pasta, olive oil |
| Snack | Apple and almonds | Macadamia nuts | Apple and almonds |
| Calories | 1,779 | 1,916 | 1,970 |
| Protein | 102 g | 102 g | 92 g |
| Carbohydrate | 141 g | 26 g | 209 g |
| Fat | 96 g | 159 g | 91 g |
| Fiber | 34 g | 14 g | 39 g |
| Protein / carbs / fat (% calories) | 22 / 31 / 47 | 21 / 5 / 74 | 18 / 41 / 40 |
Calculation: raw or as-served portions × per-100 g values from USDA FoodData Central (SR Legacy). Sample days are illustrations, not prescriptions.
The Mediterranean day delivers the most fiber (39 g) from beans, grains and fruit; the keto day the least (14 g), which is below the Institute of Medicine’s adequate intake of 14 g per 1,000 calories (National Academies, DRI for macronutrients). Carbohydrate ranges from 26 g to 209 g across diets that are all described as “healthy eating.”
What is the best evidence for each diet?
The four diets have very different research behind them. This table lists the strongest study we found for each, with what it tested.
| Diet | Key study | Design and size | Headline result |
|---|---|---|---|
| Mediterranean | PREDIMED, republished 2018 (PubMed) | Randomized trial, 7,447 adults aged 55–80 at high cardiovascular risk, median 4.8 years | Major cardiovascular events lower with Mediterranean diet plus olive oil (hazard ratio 0.69) or nuts (0.72) vs a reduced-fat control diet |
| Keto | Bueno et al., 2013 (PubMed) | Meta-analysis of 13 randomized trials, 12+ months | 0.91 kg more weight loss than low-fat diets; lower triglycerides and diastolic blood pressure; higher LDL cholesterol |
| Paleo | Manheimer et al., 2015 (PubMed) | Meta-analysis of 4 randomized trials, 159 participants, up to 6 months | Greater short-term improvements in waist size, triglycerides and blood pressure than guideline diets; moderate-quality evidence |
| Whole30 | None found | A PubMed search for “whole30” returned no indexed studies (September 2026) | No controlled evidence for the program itself |
PREDIMED’s original 2013 report was withdrawn and republished in 2018 after protocol deviations were found; the republished analysis still found a benefit.
The Mediterranean diet is the only one of the four tested against hard outcomes such as heart attacks and strokes. Paleo and keto trials measured risk factors like weight and blood fats, over shorter periods. Whole30 hasn’t been studied directly.
Which diet should you choose?
| Your main goal | Best fit | Why |
|---|---|---|
| Long-term heart health with the most evidence | Mediterranean | Outcome data from PREDIMED |
| Whole-food, grain-free eating without counting | Paleo | Simple food rules, fruit and starch allowed |
| Finding out whether dairy, grains or legumes bother you | Whole30 | Built-in elimination and reintroduction |
| Very low carbohydrate, including for a medical reason under supervision | Keto | Designed around carb restriction |
| Budget-friendly eating | Mediterranean | Beans, whole grains and canned fish are cheap; see how much paleo costs |
| Blood sugar concerns | Talk to your clinician first | All four change carbohydrate intake; see paleo and type 2 diabetes |
Many people end up blending: a paleo base with Mediterranean habits such as more fish, olive oil and, if tolerated, some legumes. Our paleo vs Mediterranean diet guide covers that combination in detail, and paleo vs keto explains the carb math for a paleo-keto hybrid.
Common mistakes when choosing between diets
- Choosing by headline weight loss. Differences between diets in trials are small; adherence matters more.
- Treating Whole30 as a permanent diet. It’s designed for 30 days plus reintroduction.
- Keto without vegetables. Low-starch vegetables are the main fiber source on keto.
- “Mediterranean” as pasta and bread. The pattern centers on vegetables, legumes, fish and olive oil.
- Ignoring medical conditions. If you take diabetes or blood pressure medication, diet changes can change what you need.
Frequently asked questions about paleo, keto, Whole30 and Mediterranean diets
What is the main difference between paleo and keto?
Paleo eliminates grains, legumes and dairy but allows carbohydrate from whole foods such as fruit and sweet potatoes. Keto restricts total carbohydrate to under about 50 g a day, often 20 g, regardless of source, and allows dairy. A banana is paleo but not keto; cheese is keto but not paleo.
Is Whole30 the same as paleo?
They overlap, but they differ in purpose. Both cut grains, legumes, dairy and processed food. Whole30 is a strict 30-day elimination that also bans honey, maple syrup, alcohol and paleo-style treats, followed by a structured reintroduction. Paleo is an ongoing lifestyle with more flexibility.
Which diet is best for long-term heart health?
Of the four, the Mediterranean diet has the strongest evidence. In the PREDIMED trial of 7,447 high-risk adults, a Mediterranean diet supplemented with olive oil or nuts reduced major cardiovascular events compared with a reduced-fat control diet. Paleo and keto have shorter studies of risk factors rather than outcomes.
Can you combine elements of these diets?
Yes. A common approach is a paleo base plus Mediterranean habits: fish twice a week, olive oil as the main fat, plenty of vegetables and, if you tolerate them, some legumes. Others use Whole30 for 30 days to test foods, then settle into paleo or Mediterranean eating afterward.
Which of these diets is easiest to follow?
For most people, the Mediterranean diet, because nothing is fully excluded and it fits restaurant and family meals. Paleo is next. Keto requires carb counting, and Whole30’s no-exceptions rules are demanding but only last 30 days.
Which diet is cheapest?
The Mediterranean diet usually costs least because it includes beans, lentils, whole grains and canned fish. Paleo and keto lean on meat, fish, nuts and produce, which cost more per calorie. Our paleo cost analysis uses federal price data to show where the difference comes from.
Your next step: pick the diet you can keep for a year
Write down the foods you’d refuse to give up, then check them against the matrix above. The diet that keeps most of them is usually the one you’ll stick with. For more comparisons, visit the paleo diet comparisons hub.
Consider this general nutrition reading, not a replacement for advice from your doctor or a registered dietitian, especially if you have a medical condition or take medication.
Research cited in this guide
- Diet Review: Paleo Diet – Harvard T.H. Chan School of Public Health
- Diet Review: Ketogenic Diet – Harvard T.H. Chan School of Public Health
- Diet Review: Mediterranean Diet – Harvard T.H. Chan School of Public Health
- Whole30 Program Rules – Whole30
- Primary Prevention of Cardiovascular Disease with a Mediterranean Diet (Estruch et al., 2018) – PubMed
- Very-low-carbohydrate ketogenic diet v. low-fat diet for long-term weight loss (Bueno et al., 2013) – PubMed
- Paleolithic nutrition for metabolic syndrome (Manheimer et al., 2015) – PubMed
- FoodData Central (SR Legacy) – U.S. Department of Agriculture