What does the research show about paleo diet?

Paleo diet

Meta-analyses of randomized trials find Paleolithic diets lowered weight about 2 to 3.5 kg more than comparison diets, and lowered blood pressure, triglycerides and LDL cholesterol. Results for blood sugar and insulin were mixed. Trials found lower iodine and calcium intake, and urinary iodine halved within 6 months in one 2-year trial in postmenopausal women.

Add to Bio HackChecked 2026-11-13

Status: A dietary pattern, not a regulated product.
Also called: paleo, Paleolithic diet, Palaeolithic diet, caveman diet, Stone Age diet, hunter-gatherer diet
Followed for: weight loss, blood pressure, cholesterol, blood sugar, inflammation, longevity

Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on

Shown to help5

StrongShown to produce about 2 to 3.5 kg more weight loss than comparison diets in adults, with the fat-loss lead not significant at 2 years in one trial.
StrongShown to lower blood pressure more than comparison diets in adults, by about 3 to 4 mmHg diastolic and 4 to 6 mmHg systolic.
StrongShown to lower total and LDL cholesterol and triglycerides more than comparison diets in adults, though some pooled results depended on single trials.
ModerateShown in two reviews to lower CRP about 0.4 to 0.8 mg/L more than comparison diets in adults, with one result sensitive to single trials.
LimitedLinked to 10% lower all-cause mortality among people whose diets scored highest for a Paleolithic pattern in cohort studies.

Reported risks4

LimitedOne trial found urinary iodine fell by half within 6 months in postmenopausal women, while it held steady on a Nordic guideline diet.How often is not known
LimitedSmall trials found calcium intake about 290 mg a day lower than on a national guideline diet, and 60% of need on a modified version.How often is not known
LimitedOne small study found vitamin D from food averaged 29.6% of need on a modified Paleolithic diet, with blood levels rising when supplements were taken.How often is not known
LimitedOne small study found choline from food averaged 73.2% of need on a modified Paleolithic diet that excludes eggs.How often is not known

What people follow it for, and what was found

Shown to help5

Strong

Weight loss

Shown to produce about 2 to 3.5 kg more weight loss than comparison diets in adults, with the fat-loss lead not significant at 2 years in one trial.

Compared with control diets the source does not describe [1]; diets based on official recommendations, mostly higher in vegetables, whole grains and low-fat dairy [2]; control diets the source does not describe [3]; a diet following the Nordic Nutrition Recommendations [4]

The numbers and sources

Effect: In 8 RCTs, weight fell 2.17 kg more than on control diets (95% CI 0.87 to 3.48), with waist 2.90 cm and body fat 1.38 points lower [1]. In 11 randomized studies, weight fell 3.52 kg more than on diets based on official recommendations (95% CI 1.79 to 5.26, I² 24%) [2]. In 19 RCTs, weight fell 1.74 kg more (95% CI 0.91 to 2.57) [3]. In a 2-year trial, fat mass fell 6.5 kg against 2.6 kg on a Nordic guideline diet at 6 months (p < 0.001), and 4.6 kg against 2.9 kg at 24 months (p 0.095) [4].
Population: Adults with and without chronic disease [1][2][3]; 70 postmenopausal women with obesity, mean age 60 [4].
Sources: [1], [2], [3], [4]
Caveats: Most trials were small and short [2]. In the 2-year trial, adherence to the protein target was poor [4].

Strong

Blood pressure

Shown to lower blood pressure more than comparison diets in adults, by about 3 to 4 mmHg diastolic and 4 to 6 mmHg systolic.

Compared with control diets the source does not describe [1], [3]; a control group the source does not describe [5]

The numbers and sources

Effect: Systolic pressure fell 4.24 mmHg more (95% CI 1.38 to 7.11) and diastolic 2.95 mmHg more (95% CI 1.18 to 4.72) [1]. In people with metabolic disorders, systolic fell 5.89 mmHg (95% CI 1.86 to 9.97) and diastolic 4.01 mmHg (95% CI 1.80 to 6.21) [5]. Diastolic fell 3.28 mmHg in 19 RCTs (95% CI 2.01 to 4.55) [3].
Population: Adults in 8 RCTs [1]; adults with metabolic disorders in 10 RCTs [5]; adults in 19 RCTs [3].
Sources: [1], [3], [5]
Caveats: In [1], the blood pressure result changed when single studies were removed.

Strong

Cholesterol and triglycerides

Shown to lower total and LDL cholesterol and triglycerides more than comparison diets in adults, though some pooled results depended on single trials.

Compared with control diets the source does not describe [1], [3]; a diet following the Nordic Nutrition Recommendations [4]; a control group the source does not describe [5]

The numbers and sources

Effect: In people with metabolic disorders, total cholesterol fell 0.32 mmol/L (95% CI 0.15 to 0.49), triglycerides 0.29 mmol/L (95% CI 0.16 to 0.42) and LDL 0.35 mmol/L (95% CI 0.03 to 0.67) more than on control diets [5]. In 19 RCTs, total cholesterol fell 0.15, LDL 0.24 and triglycerides 0.16 more, in units the abstract does not state [3]. A third review found lower total cholesterol, triglycerides and LDL and higher HDL [1]. Triglycerides fell more than on a Nordic guideline diet at 6 and 24 months [4].
Population: Adults with metabolic disorders [5]; adults in 19 RCTs [3]; adults in 8 RCTs [1]; postmenopausal women with obesity [4].
Sources: [1], [3], [4], [5]
Caveats: In [1], lipid results changed when single studies were removed.

Moderate

Inflammation markers

Shown in two reviews to lower CRP about 0.4 to 0.8 mg/L more than comparison diets in adults, with one result sensitive to single trials.

Compared with control diets the source does not describe [1]; a control group the source does not describe [5]

The numbers and sources

Effect: CRP fell 0.41 mg/L more than on control diets (95% CI 0.008 to 0.81) [1] and 0.84 mg/L more in people with metabolic disorders (95% CI 0.06 to 1.62) [5].
Population: Adults in 8 RCTs [1]; adults with metabolic disorders in 10 RCTs [5].
Sources: [1], [5]
Caveats: Confidence intervals reach close to zero. In [1], the CRP result changed when single studies were removed. CRP is a blood marker, not a disease outcome.

Limited

Long-term mortality

Linked to 10% lower all-cause mortality among people whose diets scored highest for a Paleolithic pattern in cohort studies.

Compared with people whose diets scored lowest for a Paleolithic pattern, in cohorts [3]

The numbers and sources

Effect: In 12 prospective cohorts, the highest adherers had lower all-cause mortality (RR 0.90, 95% CI 0.87 to 0.94), cancer mortality (RR 0.90, 95% CI 0.85 to 0.97) and coronary heart disease incidence (RR 0.84, 95% CI 0.70 to 1.00) [3].
Population: Adults in 12 prospective cohort studies, observational [3].
Sources: [3]
Caveats: Observational studies scoring how closely ordinary diets matched a Paleolithic pattern, not trials of people following the named diet. They cannot separate the diet from other differences between people.

Mixed results1

Moderate

Blood sugar and insulin

Mixed results: two reviews found lower fasting insulin, while a review against Mediterranean, diabetes and guideline diets found no difference in glucose, insulin or HbA1c.

Compared with control diets the source does not describe [3]; a control group the source does not describe [5]; the Mediterranean diet, a diabetes diet and a diet following Dutch Health Council advice [6]

The numbers and sources

Effect: Against Mediterranean, diabetes and Dutch guideline diets, fasting glucose (SMD -0.34, 95% CI -0.87 to 0.18), fasting insulin, HOMA-IR and HbA1c (SMD -0.38, 95% CI -0.87 to 0.11) did not differ [6]. In people with metabolic disorders, HOMA-IR fell 0.39 (95% CI 0.08 to 0.70) and fasting insulin 12.17 μU/mL (95% CI 0.08 to 24.26) [5]. In 19 RCTs, fasting insulin fell 1.01 (95% CI 0.57 to 1.45) [3].
Population: 98 people with altered glucose metabolism in 4 studies [6]; adults with metabolic disorders [5]; adults in 19 RCTs [3].
Sources: [3], [5], [6]
Caveats: The null review was small [6]. The reviews used different comparison diets.

How trials defined it

Trials defined the diet as lean meat, fish, vegetables, fruits and nuts, avoiding grains, dairy, processed foods, and added sugar and salt [1]. In a 2-year trial, it was eaten without a calorie limit and compared with a Nordic guideline diet [4]. A 4-week trial compared it, eaten freely, with the Australian national guide [7]. Comparison diets across reviews included Mediterranean, diabetes and national guideline diets [6].

Risks

Reported risks4

LimitedStudied in womenHow often is not known

Iodine

One trial found urinary iodine fell by half within 6 months in postmenopausal women, while it held steady on a Nordic guideline diet.

The numbers and sources

How common: How often is not known: the sources give no rate.
Effect: Median 24-hour urinary iodine concentration fell from 71.0 to 36.0 μg/L at 6 months (p 0.001), and 24-hour iodine excretion from 134.0 to 77.0 μg/d. Levels did not change on the comparison diet. FT4 and TSH did not differ, and FT3 was lower at 6 months [8]. In a 4-week trial, iodine intake was 47.9 μg a day lower than on the Australian national guide diet (95% CI 16.5 to 79.2) [7].
Population: 70 postmenopausal women with overweight or obesity over 2 years [8]; 39 women over 4 weeks [7].
Sources: [7], [8]
Caveats: The diet excludes table salt and dairy, which the authors call two of the largest iodine sources [8]. Small trials in women.

LimitedHow often is not known

Calcium

Small trials found calcium intake about 290 mg a day lower than on a national guideline diet, and 60% of need on a modified version.

The numbers and sources

How common: How often is not known: the sources give no rate.
Effect: Calcium intake was 292 mg a day lower than on the Australian national guide diet after 4 weeks (95% CI 99 to 486) [7]. In a 3-week study, calcium intake changed unfavorably [9]. On a modified Paleolithic diet for multiple sclerosis, calcium from food averaged 60.3% of individual need, and serum calcium did not change [10].
Population: 39 women [7]; volunteers without known disease, 14 completing and 6 with full dietary data [9]; 19 people with progressive multiple sclerosis [10].
Sources: [7], [9], [10]
Caveats: Intake, not bone outcomes. Small studies, one uncontrolled [9].

LimitedHow often is not known

Vitamin D

One small study found vitamin D from food averaged 29.6% of need on a modified Paleolithic diet, with blood levels rising when supplements were taken.

The numbers and sources

How common: How often is not known: the sources give no rate.
Effect: Vitamin D from food averaged 29.6% of individual need. With supplements, 9 of 19 exceeded the upper limit, and serum vitamin D rose over the study [10].
Population: 19 people with progressive multiple sclerosis on a modified Paleolithic diet [10].
Sources: [10]
Caveats: One small study of a modified version that also excludes eggs.

LimitedHow often is not known

Choline

One small study found choline from food averaged 73.2% of need on a modified Paleolithic diet that excludes eggs.

The numbers and sources

How common: How often is not known: the sources give no rate.
Effect: Choline from food averaged 73.2% of individual need [10].
Population: 19 people with progressive multiple sclerosis on a modified Paleolithic diet [10].
Sources: [10]
Caveats: One small study of a modified version that excludes eggs, dairy and gluten-containing grains [10].

Supplements to consider

The nutrients research linked to this diet running short, each with its own page.

Sources

Ghaedi E, Mohammadi M, Mohammadi H, et al. Effects of a Paleolithic Diet on Cardiovascular Disease Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Advances in Nutrition. 2019. https://doi.org/10.1093/advances/nmz007
de Menezes EVA, Sampaio HAC, Carioca AAF, et al. Influence of Paleolithic diet on anthropometric markers in chronic diseases: systematic review and meta-analysis. Nutrition Journal. 2019. https://doi.org/10.1186/s12937-019-0457-z
Bahrami M, Bakhshimoghaddam F, Ahangarpour A, et al. The Paleolithic diet and chronic disease risk: a GRADE-assessed systematic review and dose-response meta-analysis of prospective cohort studies and randomized controlled trials. Critical Reviews in Food Science and Nutrition. 2026. https://doi.org/10.1080/10408398.2025.2576815
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. European Journal of Clinical Nutrition. 2014. https://doi.org/10.1038/ejcn.2013.290
Sohouli MH, Fatahi S, Lari A, et al. The effect of paleolithic diet on glucose metabolism and lipid profile among patients with metabolic disorders: a systematic review and meta-analysis of randomized controlled trials. Critical Reviews in Food Science and Nutrition. 2022. https://doi.org/10.1080/10408398.2021.1876625
Jamka M, Kulczyński B, Juruć A, et al. The Effect of the Paleolithic Diet vs. Healthy Diets on Glucose and Insulin Homeostasis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Journal of Clinical Medicine. 2020. https://doi.org/10.3390/jcm9020296
Genoni A, Lyons-Wall P, Lo J, et al. Cardiovascular, Metabolic Effects and Dietary Composition of Ad-Libitum Paleolithic vs. Australian Guide to Healthy Eating Diets: A 4-Week Randomised Trial. Nutrients. 2016. https://doi.org/10.3390/nu8050314
Manousou S, Stål M, Larsson C, et al. A Paleolithic-type diet results in iodine deficiency: a 2-year randomized trial in postmenopausal obese women. European Journal of Clinical Nutrition. 2018. https://doi.org/10.1038/ejcn.2017.134
Osterdahl M, Kocturk T, Koochek A, et al. Effects of a short-term intervention with a paleolithic diet in healthy volunteers. European Journal of Clinical Nutrition. 2008. https://doi.org/10.1038/sj.ejcn.1602790
Titcomb TJ, Bisht B, Moore DD, et al. Eating Pattern and Nutritional Risks among People with Multiple Sclerosis Following a Modified Paleolithic Diet. Nutrients. 2020. https://doi.org/10.3390/nu12061844

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