The paleo diet is an eating pattern built around foods presumed to have been available to Paleolithic hunter-gatherers: meat, fish, eggs, vegetables, fruits, nuts and seeds. It leaves out grains, legumes, dairy, added sugar, salt and most processed foods. Small, short trials have found greater short-term changes in waist size, body weight and triglycerides than guideline-based diets, but longer-term data are limited and the pattern can fall short on calcium and iodine.
Key Takeaways
- Paleo emphasizes meat, fish, eggs, vegetables, fruit, nuts and seeds, and excludes grains, legumes, dairy, added sugar, salt and processed foods.
- A 2015 meta-analysis of four randomized trials (159 participants) found greater short-term improvements in waist circumference and triglycerides with paleo than with guideline-based control diets.
- In a 2-year trial in 70 women, paleo produced more fat loss at 6 months, but the difference was no longer significant at 24 months.
- Leaving out dairy and iodized salt can lower calcium and iodine intake; one 2-year trial measured a drop in iodine status on paleo.
- The 2025-2030 Dietary Guidelines encourage whole grains and dairy and keep saturated fat at or below 10% of calories, so a paleo plan needs planning to stay balanced.
- Talk with your doctor or a registered dietitian before starting if you have a medical condition or take prescription medication.
Evidence grade: Moderate. Several small randomized trials, most lasting six months or less, point the same way for waist size, weight and triglycerides, but the only 2-year trial found the extra fat loss faded and no trial has measured long-term health outcomes.
What Is the Paleo Diet?
The paleo diet, sometimes called the Paleolithic or stone age diet, tries to mimic the kinds of foods hunter-gatherers ate before farming. In practice that means whole, minimally processed foods: lean meat, fish and shellfish, eggs, vegetables, fruit, nuts and seeds, and oils such as olive or avocado oil.
What sets paleo apart from most mainstream advice is what it removes. Researchers reviewing the diet note that its exclusion of grains, dairy and processed "products of industry" differs sharply from the dietary patterns recommended in national guidelines [3]. Table salt is also left out, which matters for iodine intake [6].
That gap with official guidance is the main source of expert disagreement. Paleo's emphasis on vegetables, fruit and unprocessed foods lines up with current advice. Its removal of whole grains, legumes and dairy does not.
What to Eat and What to Avoid
The table below compares a strict paleo plan with the 2025-2030 Dietary Guidelines for Americans, which were released in January 2026 [8].
| Food group | Strict paleo | What to know |
|---|---|---|
| Meat, poultry, fish, eggs | Included | Fish and lean cuts help keep saturated fat within the guideline limit of 10% of calories [8]. |
| Vegetables and fruit | Included | Matches guideline advice to eat whole vegetables and fruit in their original form [8]. |
| Nuts and seeds | Included (peanuts excluded) | Peanuts are legumes, so strict paleo leaves them out. |
| Oils and fats | Olive, avocado, nut and coconut oils commonly used | The guidelines suggest prioritizing oils with essential fatty acids, such as olive oil [8]. |
| Grains (wheat, oats, rice, corn) | Excluded | The guidelines encourage 2 to 4 servings of fiber-rich whole grains a day [8]. |
| Legumes (beans, lentils, peas, peanuts) | Excluded | Legumes are common sources of fiber and plant protein. |
| Dairy | Excluded | About 72% of U.S. calcium intake comes from dairy foods [1]. |
| Added sugar, salt, processed foods | Excluded | The guidelines also advise avoiding highly processed foods and added sugars [8]. |
Why grains and legumes are left out
Paleo advocates argue that grains and legumes are relatively recent additions to the human diet and point to compounds such as phytic acid. Phytic acid and oxalic acid can bind calcium and reduce how much the body absorbs [1]. That effect is real, but it is not a reason most nutrition authorities give for avoiding these foods, and whole grains remain part of U.S. guidance [8].
A sample paleo day
- Breakfast: eggs with sauteed spinach and a handful of raspberries.
- Snack: pumpkin seeds and a few dried apricots.
- Lunch: spaghetti squash or zucchini noodles with shrimp and tomato sauce.
- Snack: a banana with almond butter.
- Dinner: baked salmon or chicken with sweet potato, broccoli and kale.
Choosing salmon, broccoli and kale at dinner is deliberate: these are among the nondairy foods that supply calcium [1].
What the Research Shows
Paleo has been tested in a handful of randomized trials. Most were small and lasted weeks or months, and most measured risk markers rather than long-term health outcomes.
- 2015 meta-analysis. Pooling four randomized trials with 159 participants who had at least one component of metabolic syndrome, researchers found paleo produced greater short-term improvements than guideline-based control diets in waist circumference (about 2.4 cm more) and triglycerides. Estimates for blood pressure, HDL and fasting blood sugar also favored paleo, but their confidence intervals included no effect. The reviewers rated the evidence as moderate quality and called for more research [3].
- 2-year trial in women. Seventy postmenopausal women with obesity followed either paleo or the Nordic Nutrition Recommendations without calorie counting. Both groups lost fat. The paleo group lost more at 6 months (6.5 kg vs 2.6 kg of fat mass), but at 24 months (4.6 kg vs 2.9 kg) the difference was no longer statistically significant. Triglycerides fell more on paleo at both time points, and the paleo group did not reach its protein target [4].
- 4-week trial in healthy women. Among 39 healthy women, the paleo group lost about 2 kg more than a group following Australian dietary guidelines, with no difference between groups in cardiovascular and metabolic markers. The paleo group ate less carbohydrate, sodium, calcium and iodine and more fat [5].
- 4-month study in adults with high cholesterol. Twenty adults ate a traditional heart-healthy diet for four months and then a paleo diet for four months. On paleo, total and LDL cholesterol and triglycerides were lower and HDL was higher. Because everyone followed the diets in the same order and there was no randomized control group, the result is hard to generalize [7].
What these studies cannot tell you
The trials were small and short, participants often lost weight, and weight loss alone can shift these markers. None followed people long enough to measure heart attacks, strokes or other events. Current evidence supports paleo as one option that can improve some short-term measures, not as a pattern proven to be better than other balanced diets over the long run.
Paleo and Weight
In the trials above, people on paleo often lost more weight early on without being told to count calories, likely because the diet removes many processed, energy-dense foods. The extra loss was modest, about 2 kg over 4 weeks in one study [5], and in the longest trial the advantage over a standard healthy diet shrank by 2 years [4]. Results vary from person to person, and paleo is best viewed as a change in eating habits rather than a quick fix.
Nutrient Gaps to Plan For
Calcium
Adults need 1,000 to 1,200 mg of calcium a day, depending on age and sex [1]. Without dairy, the women in the 4-week trial ate about 290 mg less calcium per day than the comparison group [5]. Nondairy sources include kale, broccoli, bok choy, and canned sardines or salmon with bones. Spinach is a weaker choice because only about 5% of its calcium is absorbed [1]. For more on this mineral, see our guide to calcium and bone health in older adults.
Iodine
Iodized salt and dairy are two of the largest iodine sources in many diets, and strict paleo removes both. In the 2-year Swedish trial, urinary iodine fell by about half after 6 months on paleo but did not change on the comparison diet, and the authors suggested considering iodine supplementation for people on a paleo diet [6]. Adults need 150 mcg of iodine a day. Seafood, seaweed, eggs and dairy are good food sources, and specialty salts such as sea salt or Himalayan salt are not usually iodized [2].
If you eat strict paleo and rarely have seafood or eggs: OPA Advanced Iodine+ provides 300 mcg of iodine from kelp per two-capsule serving, which is twice the adult RDA of 150 mcg and below the 1,100 mcg daily upper limit for iodine from all sources [2]. It also contains a kelp and greens blend and an herbal blend that includes turmeric, reishi and guggul, and the label notes fish and crustacean shellfish ingredients. Food sources come first; check with your clinician before adding iodine, especially if you have a thyroid condition or take thyroid medicine.
Saturated fat and fiber
A paleo plan heavy in fatty red meat can push saturated fat above the 10%-of-calories limit in the Dietary Guidelines [8]. Favoring fish, poultry, nuts and olive oil helps. Paleo also removes whole grains and legumes, two major fiber sources, so it takes extra vegetables, fruit, nuts and seeds to keep fiber intake up. For more on fat types, see our guide to dietary fats.
Paleo vs Other Popular Eating Patterns
Paleo is defined by food quality: it allows fruit and starchy vegetables such as sweet potatoes, as long as foods are unprocessed. The ketogenic diet is defined by carbohydrate restriction, so it limits fruit and starchy vegetables but often allows dairy. The Mediterranean diet shares paleo's focus on vegetables, fish, nuts and olive oil but keeps whole grains, legumes and some dairy. Some people follow a modified paleo plan that adds back dairy or legumes, which also makes calcium and fiber easier to cover.
Safety and Interactions
- Talk to a professional first if you are pregnant or breastfeeding, have a chronic medical condition, take prescription medication, or have a history of disordered eating.
- Watch calcium and iodine. Plan nondairy calcium sources and iodine-rich foods, or discuss supplements with your clinician [1,2,6].
- Iodine supplements can interact with medicines. High-dose iodine can interact with antithyroid medicines such as methimazole, and potassium iodide taken with ACE inhibitors or potassium-sparing diuretics can raise blood potassium. Tell your doctor or pharmacist about every supplement you take [2].
- Stay under the upper limit. The upper limit for iodine is 1,100 mcg a day for adults from food, drinks and supplements combined [2].
- Keep saturated fat in range by choosing fish, poultry and plant fats more often than fatty red and processed meats [8].
Frequently Asked Questions
What do you eat on a paleo diet?
Paleo is built on meat, fish, eggs, vegetables, fruit, nuts, seeds and healthy oils such as olive oil. It leaves out grains, legumes, dairy, added sugar, salt and processed foods.
Can you lose weight on the paleo diet?
Many people do in the short term. In trials, paleo groups lost about 2 kg more over 4 weeks than a standard-diet group, and more fat over 6 months, but in the longest trial the advantage was no longer significant after 2 years [4,5]. Results vary by person.
Can I eat dairy on a paleo diet?
Strict paleo excludes dairy. Some people follow a modified plan that includes it. If you skip dairy, plan other calcium sources such as kale, broccoli, bok choy and canned fish with bones, because adults need 1,000 to 1,200 mg of calcium a day [1].
Is the paleo diet safe for everyone?
Not necessarily. It removes whole food groups and can be high in saturated fat if it relies on fatty meat. Anyone with a medical condition, who is pregnant, or who takes medication should speak with a doctor or registered dietitian first.
How is paleo different from keto?
Paleo focuses on unprocessed foods and allows fruit and starchy vegetables. Keto focuses on keeping carbohydrates very low and often includes dairy. The two overlap in places but are built on different rules.
How long should you follow the paleo diet?
There is no set length, and long-term research is limited: the longest trial lasted 2 years [4]. If you follow it long term, review your calcium, iodine, fiber and saturated fat intake with a dietitian.
Sources
- NIH Office of Dietary Supplements. Calcium: Fact Sheet for Health Professionals. National Institutes of Health.
- NIH Office of Dietary Supplements. Iodine: Fact Sheet for Consumers. National Institutes of Health.
- Manheimer EW, van Zuuren EJ, Fedorowicz Z, Pijl H. Paleolithic nutrition for metabolic syndrome: systematic review and meta-analysis. Am J Clin Nutr. 2015.
- Mellberg C, Sandberg S, Ryberg M, et al. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial. Eur J Clin Nutr. 2014.
- Genoni A, Lyons-Wall P, Lo J, Devine A. Cardiovascular, metabolic effects and dietary composition of ad-libitum Paleolithic vs. Australian Guide to Healthy Eating diets: a 4-week randomised trial. Nutrients. 2016.
- Manousou S, Stal M, Larsson C, et al. A Paleolithic-type diet results in iodine deficiency: a 2-year randomized trial in postmenopausal obese women. Eur J Clin Nutr. 2018.
- Pastore RL, Brooks JT, Carbone JW. Paleolithic nutrition improves plasma lipid concentrations of hypercholesterolemic adults to a greater extent than traditional heart-healthy dietary recommendations. Nutr Res. 2015.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025-2030. realfood.gov. 2026.
Disclosure: OPA Nutrition sells supplements, including products mentioned in this article. This content is for education only and is not medical advice. Statements about dietary supplements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease. Talk to your healthcare provider before using any supplement, especially if you take medication or have a medical condition.
Written and reviewed by Michael Gonzales, Founder, OPA Nutrition · Last reviewed: · How OPA researches and writes
