Paleo Diet

Twentieth-century proposals

A 2024 review in Metabolites traces the modern Paleo idea to several works. It cites Walter Voegtlin's 1975 book The Stone Age Diet as earlier work that led to the phenomenon, and states that Eaton and Konner popularized the idea in 1985 that moving away from humanity's evolutionary past contributes to chronic disease. The same review lists The Paleolithic Prescription by S. Boyd Eaton, Marjorie Shostak and Melvin Konner in 1989 and Loren Cordain's The Paleo Diet in 2002, revised in 2010.

The evolutionary discordance hypothesis

An Australian Family Physician review describes the diet as resting on the evolutionary discordance hypothesis, which it summarizes as the view that human evolution ceased about 10,000 years ago, so that bodies are poorly matched to agricultural and industrial foods. The review adds that anthropologists have criticized this view and that the diet's anthropological validity is questionable.

What archaeology and anthropology add

Archaeological work does not describe one uniform Paleolithic menu. Excavated carbonised food remains from Franchthi Cave in Greece and Shanidar Cave in Iraqi Kurdistan include processed plant foods in which pounded pulses were a common ingredient, and the authors argue that bitter and astringent plants featured in Palaeolithic cooking in South-west Asia and the Eastern Mediterranean.

A 2024 isotope study of people from Taforalt, Morocco, dated to about 15,000 to 13,000 years ago, concluded that plants were a major protein source and estimated roughly half of the diet, while noting the estimate is approximate, the sample was small (about a dozen adults) and the people were not strict vegetarians. An earlier study of the same site had reported mostly meat. A 2024 review also states that humans were never strict carnivores. These findings concern particular places and periods, so they neither confirm nor refute any modern menu.

Names in use

The pattern is called the Paleo diet, the Paleolithic diet, the caveman diet or the Stone Age diet, and trial reports also use the spelling Palaeolithic and phrases such as Palaeolithic-type diet or Paleolithic nutrition. Harvard's Nutrition Source lists caveman and Stone-Age as alternative names. The terms refer to a modern eating pattern that is inspired by a hypothesis about the past, not to a record of what any Paleolithic group ate.

Definitions differ between studies

There is no single standard definition used across research. A systematic review of trials noted that the Paleolithic arms of the included studies were not always consistent in their restrictions. A review of carbohydrate-restricted diets found that the two trials labeled Paleolithic prescribed about 28 to 30 percent of energy from carbohydrate, so results from one version of the pattern do not automatically apply to another.

Related Machipedia pages

Machipedia covers the wider family of eating patterns on its Dietary Approaches page, which this page does not duplicate. Related patterns that have their own pages include Low Carbohydrate Nutrition, Carnivore Diet, Autoimmune Protocol Diet and Mediterranean Diet. The British Dietetic Association names the paleo diet alongside low carbohydrate diets and the carnivore diet as examples of diets that avoid or severely limit a whole food group. The sources reviewed for this page do not compare these patterns with one another.

Foods emphasized and excluded

Harvard's Nutrition Source describes the diet as built around lean meat, fish, fruit, vegetables, nuts and seeds, and as leaving out whole grains, dairy, legumes, refined sugar and most processed products, without a stress on calorie counting or portion sizes. A meta-analysis of cardiovascular risk factors gives a similar summary, advising lean meat, fish, vegetables, fruits and nuts and avoiding grains, dairy products, processed foods and added sugar and salt. A 2023 overview adds that refined vegetable oils and alcohol are also excluded, and includes olive oil among foods used.

How trials delivered the pattern

In research the pattern has usually been delivered as dietary advice rather than a fixed menu. In a systematic review of four trials, three gave dietary recommendations and one provided home-delivered meals. A Swedish crossover trial in type 2 diabetes asked participants to eat a diet based on lean meat, fish, fruits, vegetables, root vegetables, eggs and nuts for three months. Ordinary practice outside trials varies, and this page does not give meal plans.

Who guides it

The diet is mostly followed through books and self-directed reading. Dietitians are the professionals who assess and advise on eating patterns; see the Dietetics page on Machipedia. The sources reviewed for this page did not identify a training standard, register or professional title specific to the Paleo Diet.

Weight and metabolic health

Proponents and researchers have studied the pattern mainly for body weight, waist circumference, blood lipids, blood pressure and glucose control. Trials have enrolled people with metabolic syndrome components, type 2 diabetes, ischemic heart disease with impaired glucose metabolism, and obesity after menopause. The authors of the reviews describe these as risk factors and surrogate markers, not as measured heart attacks or deaths.

Claims without clinical support

Claims that the diet helps with conditions such as autism, dementia or mental illness are described in the Australian Family Physician review as unsupported by clinical research. The sources reviewed for this page did not find controlled trials establishing such uses.

Systematic reviews of randomized trials

A 2015 systematic review in the American Journal of Clinical Nutrition pooled four randomized trials with 159 participants who had at least one metabolic syndrome component, comparing the Paleolithic pattern with guideline-based control diets over six months or less. It found greater short-term improvements in waist circumference (about 2.4 cm lower) and triglycerides, with differences in blood pressure, HDL cholesterol and fasting glucose not statistically significant. GRADE certainty was rated moderate for each outcome, quality of life was not measured, and adverse events were reported in only one trial.

A 2019 meta-analysis of eight randomized trials reported lower body weight, waist circumference, body mass index and body fat and some lipid and blood pressure changes. The authors noted that results for lipids, blood pressure and C-reactive protein changed when individual studies were removed, and concluded that the evidence was not conclusive and that better-designed trials were needed.

Individual trials and their limits

A 12-week Swedish trial randomized people with ischemic heart disease and impaired glucose metabolism (29 analyzed) to a Paleolithic or Mediterranean-like diet. Weight loss was similar, while waist circumference fell more and glucose tolerance improved in the Paleolithic group. A crossover trial of 13 people with type 2 diabetes found lower HbA1c, weight and triglycerides after three months on the Paleolithic diet than on a diabetes diet, and the authors called it a pilot study.

The longest trial randomized 70 obese postmenopausal women to a Paleolithic-type or Nordic Nutrition Recommendations diet for two years. Fat mass fell more in the Paleolithic group at six months, but the difference was not significant at 24 months, triglycerides stayed lower at both times, and adherence to the intended protein intake was poor. The authors state that long-term consequences remain to be studied.

Observational findings and guideline positions

A 2025 review combined 19 randomized trials with 12 prospective cohort studies. In the cohorts, people with higher adherence to a Paleolithic-style pattern had about 10 percent lower all-cause mortality. Cohort associations cannot show that the diet caused the difference, because people who choose such a diet may differ in other ways. Only the abstract of this review was read for this page.

Harvard's Nutrition Source concludes that strong recommendations for the Paleo diet for weight loss cannot be made at this time. The British Dietetic Association lists the paleo diet among diets that avoid a whole food group, in a fact sheet about warning signs of fad diets. The sources reviewed for this page did not find a clinical guideline that recommends the Paleo Diet.

Calcium, vitamin D and other nutrients

Excluding dairy and grains reduces calcium intake. An Australian Family Physician review cites a pilot study in which calcium intake was about half of the recommended level, and warns that osteoporosis risk could rise, particularly in people already at higher risk. Harvard's Nutrition Source states that excluded food groups may raise the risk of deficiency in calcium, vitamin D and B vitamins, and reports one short study with a 53 percent drop in calcium intake after three weeks.

A systematic review of carbohydrate-restricted diets reported decreases in intakes of folate, magnesium, calcium, iron and iodine across diet types, with no deficiency diagnoses reported. In one Paleolithic trial in that review, moderate iodine deficiency rose from 15 to 73 percent of participants over six months. A 2023 overview raises methylmercury from large amounts of fish.

Cost and adherence

A modeling study cited in the Australian Family Physician review found the diet to be about 10 percent more expensive than an essential diet of similar nutritional value, which may limit use on low incomes. Harvard's Nutrition Source describes fresh meat, fish and produce as pricier than processed alternatives and notes that restrictiveness can make long-term adherence difficult.

Conditions that need individual advice

The sources reviewed for this page do not report on kidney disease, pregnancy, children or people with a history of eating disorders, so no suitability statements can be drawn for them here. A pattern that removes whole food groups can matter for people who take medicines for diabetes, as the trial participants did, or who are growing, pregnant or recovering from disordered eating. Anyone with a medical condition is advised in general to discuss dietary changes with a clinician or registered dietitian, and the diet should not delay or replace necessary medical care.