American Health & Medical Research Association
Comparison guide

Eight eating patterns compared, and why the diet you stick with beats the one you pick

In a landmark trial, sticking with a diet mattered far more than which one people chose. Here is how eight popular patterns compare on health evidence, ease, cost and climate footprint.

By the Health Research USA editorial team

Published Last updated October 2026

Written from the sources listed below; links checked October 2026. It touches on medicines, doses or health conditions and has not yet been reviewed by a licensed clinician, so use it to prepare for a conversation with yours. How we research and review

Sources15, listed below Reading time15 minutes

Where the evidence stands

  • Strong evidence MediterraneanDASHLow-carbIntermittent fasting
  • Promising but early VeganVegetarian or flexitarianPaleoKeto

Each use is rated separately, from the scorecard in this guide. Safety cautions are spelled out in the guide itself. How we grade

On this page
  1. Twenty years of trials keep finding the same tie
  2. DASH lowered blood pressure in eight weeks, with no weight loss
  3. Health evidence runs from fewer heart attacks to short-term lab numbers
  4. Keto plates carried about four times the carbon of vegan plates
  5. Cost and culture decide what lasts
  6. Diet rankings are expert votes, not experiments
  7. The scorecard: eight diets on five measures
  8. What natural-health instincts get right
  9. Questions readers ask
  10. The bottom line

Key takeaways

  • In a 2005 Boston trial of the Atkins, Ornish, Weight Watchers and Zone diets, how closely people followed their plan predicted weight loss far better than which plan they got.
  • In the original DASH trial, eating more fruits, vegetables and low-fat dairy lowered blood pressure by 11.4/5.5 points in people with hypertension within eight weeks, with weight held steady.
  • In the 2018 republished PREDIMED trial, Mediterranean diets with extra olive oil or nuts led to about 30% fewer heart attacks, strokes and heart deaths than low-fat advice.
  • As Americans eat them, keto diets carried more than four times the carbon footprint of vegan diets per 1,000 calories.
  • An Oxford modeling study found that in wealthy countries, vegan diets were the cheapest healthy, sustainable option, cutting food costs by up to a third, with vegetarian diets close behind.

Between 2000 and 2002, researchers at an academic medical center in Boston enrolled 160 adults with overweight or obesity. Each had a heart risk such as high blood pressure or high cholesterol. Nobody got to choose a diet. Forty people were assigned to each of four famous plans: Atkins, Zone, Weight Watchers and Ornish1.

A year later, the plan itself barely mattered. Average weight loss ranged from about 4.6 pounds on Atkins to 7.3 pounds on Ornish1.

What did matter was how closely people stuck with their plan. Researchers measured this with a correlation, a number from 0 (no link) to 1 (a perfect link). For sticking with the diet, it was 0.60. For which diet a person was given, it was 0.071.

Sticking was hard. About half of the Atkins and Ornish groups dropped out before the year ended1.

That finding frames this guide, the last in our series on dietary philosophies. The best diet for most people is a sound pattern they will keep. Here, eight popular patterns are weighed on health evidence, on whether people can live with them, and on what they cost your wallet and the planet.

Twenty years of trials keep finding the same tie

The Boston result was no fluke. In 2020, an international team pooled 121 randomized trials with 21,942 adults with overweight or obesity2. A randomized trial assigns people to diets by chance, so the groups start out alike.

At six months, low-carb and low-fat diets produced similar weight loss, about 10 pounds compared with usual eating. By 12 months, weight loss had shrunk and most heart benefits had faded, except on the Mediterranean diet2. Our article on macronutrients covers that analysis.

So trials can’t crown one diet for weight loss. They can show which patterns improve health, which ones people can keep, and which are lighter on the land.

DASH lowered blood pressure in eight weeks, with no weight loss

DASH stands for Dietary Approaches to Stop Hypertension. It was born in feeding studies, where researchers supplied every meal.

In the first DASH trial, published in 1997, 459 adults ate a typical American diet for three weeks. Then they were assigned to keep eating it, to add more fruits and vegetables, or to switch to a combination diet rich in fruits, vegetables and low-fat dairy, with less saturated and total fat3.

Researchers held sodium near 3 grams a day and kept weight steady, so neither could explain the results3. About 60% of the volunteers were Black adults3.

After eight weeks, the combination diet lowered blood pressure by 5.5/3.0 points overall, measured in millimeters of mercury. In the 133 people with high blood pressure, the drop was 11.4/5.53.

In 2001, the DASH-Sodium trial added salt to the test. Its 412 participants ate either a typical diet or DASH at three sodium levels, for 30 days each4. DASH at the lowest sodium level beat a typical high-sodium diet by 7.1 points of systolic pressure, the top number, in people without hypertension and 11.5 points in people with it4.

The authors concluded that eating DASH-style and cutting sodium below the 2,300 milligrams a day then recommended each lowered blood pressure, and together they worked best4.

The catch: researchers supplied the food. The 1997 authors noted their study wasn’t built to test how well people stick with DASH when they shop and cook for themselves3. If you take blood pressure medicine, tell your clinician before you change how you eat, since your doses may need a review.

Health evidence runs from fewer heart attacks to short-term lab numbers

The patterns differ most in the kind of proof behind them.

Fewer heart events: Mediterranean. The PREDIMED trial in Spain assigned 7,447 adults aged 55 to 80 at high heart risk to a Mediterranean diet with extra olive oil, one with extra nuts, or advice to cut fat5. Over a median 4.8 years, a heart attack, stroke or heart death struck 3.8% of the olive oil group, 3.4% of the nut group and 4.4% of the low-fat group5.

The original 2013 report was withdrawn after problems with how some participants were randomized. The 2018 republished analysis, cited here, found similar results even after dropping 1,588 participants whose assignments were in question5.

Lower blood pressure: DASH, in tightly controlled feeding trials34.

Mixed long-term signals: vegetarian and vegan. EPIC-Oxford followed 48,188 British adults for about 18 years. Vegetarians, including vegans, had 22% lower rates of heart disease than meat eaters, about 10 fewer cases per 1,000 people over 10 years6.

But they had 20% higher rates of stroke, about 3 more cases per 1,000, mostly from bleeding in the brain. Fish eaters had 13% less heart disease6. Studies like this show links, not proof of cause.

Short-term markers: paleo, keto and low-carb. Four small paleo trials with 159 people trimmed waists by about an inch and lowered triglycerides, a blood fat, over six months or less8.

In Stanford’s Keto-Med trial, 33 adults with prediabetes or type 2 diabetes improved blood sugar about equally on keto and on a Mediterranean-style diet. LDL cholesterol rose 10% on keto and fell 5% on the Mediterranean plan7.

Weight: no clear winner. Fasting schedules matched daily calorie cutting across 99 trials9, and named diets converged by 12 months2.

Keto plates carried about four times the carbon of vegan plates

In 2018, Joseph Poore of the University of Oxford and Thomas Nemecek compiled data from about 38,700 farms in 119 countries10. Meat, farmed fish, eggs and dairy supplied 18% of the world’s calories and 37% of its protein. Yet they took up about 83% of farmland and accounted for 56% to 58% of food’s greenhouse gas emissions10.

If the world dropped animal foods entirely, the pair estimated, farmland use would shrink by about three-quarters (76%) and food’s emissions by roughly half (49%)10.

Two findings complicate simple stories. Farms raising the same food differed in impact by as much as 50 times, so how food is produced matters. Even so, a plant substitute usually beat even the cleanest animal product10.

What about the diets people follow? Tulane University researchers scored the diets of more than 16,000 U.S. adults from a federal health survey, as people ate them12. They measured footprints in carbon dioxide equivalent, which counts all greenhouse gases in carbon dioxide terms.

Per 1,000 calories, vegan eating came to 0.69 kg, vegetarian 1.16, pescatarian 1.66, omnivore 2.23, paleo 2.62 and keto 2.9111. Meat eaters who ate Mediterranean- or DASH-style also had lower footprints than typical omnivores12.

The labels were loose. “Vegetarian,” for instance, meant under 14 grams of meat or seafood a day11. Senior author Diego Rose said people can improve both health and footprint without giving up meat entirely12.

In October 2025, the EAT-Lancet Commission, 70 experts from 35 countries, updated its “planetary health diet”14. For about 2,400 calories a day, it centers on roughly 210 grams of whole grains, 300 of vegetables, 200 of fruit, 75 of legumes and 50 of nuts14.

Animal foods are optional and modest: targets of about 250 grams of dairy, 30 each of fish and poultry, and 15 of red meat a day, which adds up to under 4 ounces of red meat a week14. The commission estimated the shift could prevent about 15 million deaths a year, a modeled figure, not a trial result14.

The British Nutrition Foundation added cautions. It noted that animal foods supply iron, zinc, calcium, iodine and B12, which can run low, especially in children, teens, pregnant women and older adults. It warned that the shift must not widen diet inequalities14.

Cost and culture decide what lasts

Many people assume eating sustainably costs more. In 2021, Oxford researchers including Marco Springmann put that to the test with World Bank food prices from 150 countries13.

For wealthy nations such as the United States, the answer was mostly no. A vegan pattern came out cheapest, trimming food costs by as much as one-third, with vegetarian eating just behind. A flexitarian pattern saved 14%, while a pescatarian one cost up to 2% more13.

There are caveats. The prices covered whole foods only, leaving out processed meat substitutes and meals eaten out. And in poorer countries, a healthy, sustainable diet would still cost at least a third more than current diets there13.

Culture matters as much as cost. A pattern has to fit the foods your family cooks and the holidays you keep. EAT-Lancet’s wide ranges, such as zero to 500 grams of dairy a day, leave room for very different cuisines14.

The Keto-Med trial offers a clue about what people find livable. Once the study ended and volunteers could eat anything, their meals looked more like the Mediterranean plan than like keto7. Our article on heritage diets shows how traditional foods from many cultures fit healthy patterns.

Diet rankings are expert votes, not experiments

U.S. News & World Report publishes yearly Best Diets ratings. They come from a panel of experts, not from new research15.

In the 2025 edition, the latest we could check, 69 panelists, including doctors, dietitians, epidemiologists, chefs and weight-loss researchers, rated 38 diets in 21 categories on a five-point scale15. The Mediterranean diet came out on top overall at 4.8. DASH scored 4.9 for high blood pressure and heart health, and the flexitarian diet led the plant-based category15.

The ratings are a useful summary of informed opinion. They are still opinion. Treat them as a starting point, then look at the trials behind them.

The scorecard: eight diets on five measures

Each cell rests on the sources cited. “Not modeled” means the Oxford cost study did not price that diet. Footprints are kilograms of carbon dioxide equivalent per 1,000 calories, as Americans ate.

Pattern Health evidence Can people stick with it? Cost in rich countries Footprint Watch out for
Mediterranean Strong evidence: about 30% fewer heart events5 Flexible; Keto-Med volunteers drifted toward it7 Not modeled13 Below typical omnivore12 Heart-event proof comes mainly from adults 55 to 80 at high risk5
DASH Strong evidence for lower blood pressure34 The landmark trials supplied the food, so they didn’t test this3 Not modeled13 Below typical omnivore12 Blood pressure medicines; tell your clinician
Vegan Promising but early for heart health; observational6 Takes planning14 Cheapest, up to a third less13 0.69, the lowest11 B12, iron, zinc, calcium and iodine, especially in pregnancy, childhood and older age14
Vegetarian or flexitarian Promising but early: less heart disease, more bleeding strokes6 Flexitarian allows small steps Vegetarian near vegan; flexitarian 14% less13 1.16 vegetarian; 1.66 pescatarian11 Iron and B12 if eggs and dairy are rare14
Paleo Promising but early: smaller waists in trials of 6 months or less8 Pooled trials lasted six months or less8 Not modeled13 2.6211 Losing whole grains, beans and dairy
Keto Promising but early for blood sugar; LDL rose 10%7 Volunteers drifted away after the trial7 Not modeled13 2.91, the highest11 Rising LDL; diabetes medicines need a plan
Low-carb Strong evidence: weight loss matched low-fat at six months; LDL fell less2 Almost half quit Atkins in a year1 Not modeled13 Depends on what replaces the carbs Diabetes medicines need a plan
Intermittent fasting Strong evidence it matches daily calorie cutting9 Varies by schedule; see our fasting guide No special foods needed Depends on what you eat Insulin, pregnancy or an eating-disorder history

To choose, ask yourself four questions:

  1. What’s my main goal? For blood pressure, DASH has the tightest trials34. For preventing heart attacks and strokes, Mediterranean has the strongest5.
  2. Which pattern looks most like food I already love? Start there, not with a stranger’s grocery list.
  3. What fits my budget? Beans, grains and vegetables anchor the cheapest patterns.
  4. Can I picture eating this way a year from now? If not, choose a milder version. A plan you keep beats a perfect plan you drop.

Before a big change, talk with a clinician if you take diabetes or blood pressure medicines or are pregnant. Our article on medicine clashes explains why. If dieting tends to turn into rigid rules or guilt, the National Alliance for Eating Disorders helpline is 1-866-662-1235. In a crisis, call or text 988.

What natural-health instincts get right

The patterns with the strongest evidence look a lot like what many natural-health readers already value: whole foods, plants at the center and meals cooked at home. In Keto-Med, the researchers credited both diets’ blood sugar gains to shared basics: plenty of nonstarchy vegetables, no added sugars and few refined grains7.

The arguments online over fat, carbs and meal timing matter less than those shared basics. Pick the version of them that suits your body, your budget and your table.

Questions readers ask

Do I have to give up meat to eat sustainably?

No. Meat eaters who ate Mediterranean- or DASH-style had smaller footprints than typical omnivores12, and the EAT-Lancet diet allows modest meat and fish14. In these studies, eating fewer animal foods and more plants shrank footprints the most1011.

Is eating sustainably more expensive?

In high-income countries, Oxford’s model found vegan, vegetarian and flexitarian diets cheaper than typical diets13. That analysis priced whole foods, not processed meat substitutes13.

Should I trust the U.S. News rankings?

Treat them as a summary of expert opinion, not as proof15. The trials behind the top-rated Mediterranean and DASH patterns are what make those ratings credible345.

The bottom line

No named diet wins on weight over the long run, and a 2005 trial showed why: sticking with a plan mattered more than which plan people got. Mediterranean and DASH eating have the strongest health evidence, plant-heavy patterns have the smallest footprints and lowest costs in wealthy countries, and keto and paleo carry the biggest footprints.

The best choice is a sound pattern you will keep, built on whole foods and plants and adapted to the food you love. If you take diabetes or blood pressure medicines or are pregnant, talk with a clinician before a big change.

About this article

This article was researched using peer-reviewed trials and reviews, university reports and nutrition-organization summaries, listed below, and was reviewed in October 2026. It is general education, not medical, legal or financial advice..

Sources

  1. Dansinger ML, Gleason JA, Griffith JL, Selker HP, Schaefer EJ. “Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Randomized Trial.” JAMA, 2005;293(1):43–53. ovid.com
  2. Ge L, Sadeghirad B, Ball GDC, et al. “Comparison of Dietary Macronutrient Patterns of 14 Popular Named Dietary Programmes for Weight and Cardiovascular Risk Factor Reduction in Adults: Systematic Review and Network Meta-Analysis of Randomised Trials.” BMJ, 2020;369:m696. bmj.com
  3. Appel LJ, Moore TJ, Obarzanek E, et al., for the DASH Collaborative Research Group. “A Clinical Trial of the Effects of Dietary Patterns on Blood Pressure.” New England Journal of Medicine, 1997;336:1117–1124 (Harvard repository copy). dash.harvard.edu
  4. Sacks FM, Svetkey LP, Vollmer WM, et al., for the DASH–Sodium Collaborative Research Group. “Effects on Blood Pressure of Reduced Dietary Sodium and the Dietary Approaches to Stop Hypertension (DASH) Diet.” New England Journal of Medicine, 2001;344:3–10 (Harvard repository record). pubmed.ncbi.nlm.nih.gov
  5. Estruch R, Ros E, Salas-Salvadó J, et al. “Primary Prevention of Cardiovascular Disease With a Mediterranean Diet Supplemented With Extra-Virgin Olive Oil or Nuts.” New England Journal of Medicine, 2018 (republished version; University of Barcelona repository). diposit.ub.edu
  6. Tong TYN, Appleby PN, Bradbury KE, et al. “Risks of Ischaemic Heart Disease and Stroke in Meat Eaters, Fish Eaters, and Vegetarians Over 18 Years of Follow-Up: Results From the Prospective EPIC-Oxford Study.” BMJ, 2019;366:l4897 (University of Oxford abstract). leap.ox.ac.uk
  7. Gardner CD, Landry MJ, Perelman D, et al. “Effect of a Ketogenic Diet Versus Mediterranean Diet on Glycated Hemoglobin in Individuals With Prediabetes and Type 2 Diabetes Mellitus: The Interventional Keto-Med Randomized Crossover Trial.” American Journal of Clinical Nutrition, 2022 (Stanford-hosted PDF). med.stanford.edu
  8. Manheimer EW, van Zuuren EJ, Fedorowicz Z, Pijl H. “Paleolithic Nutrition for Metabolic Syndrome: Systematic Review and Meta-Analysis.” American Journal of Clinical Nutrition, 2015 (abstract record). nutrition-evidence.com
  9. Semnani-Azad Z, et al. “Intermittent Fasting Strategies and Their Effects on Body Weight and Other Cardiometabolic Risk Factors: Systematic Review and Network Meta-Analysis of Randomised Clinical Trials.” BMJ, 2025;389:e082007 (University of Glasgow repository record). eprints.gla.ac.uk
  10. Poore J, Nemecek T. “Reducing Food’s Environmental Impacts Through Producers and Consumers.” Science, 2018;360:987–992 (author’s accepted manuscript). josephpoore.com
  11. TABLE (University of Oxford, Swedish University of Agricultural Sciences and Wageningen University). Research summary of O’Malley K, Willits-Smith A, Rose D. “Popular Diets as Selected by Adults in the United States Show Wide Variation in Carbon Footprints and Diet Quality.” American Journal of Clinical Nutrition, 2023. tabledebates.org
  12. Tulane University. “Keto vs Vegan: Study of Popular Diets Finds Over Fourfold Difference in Carbon Footprints.” News release, March 1, 2023. news.tulane.edu
  13. University of Oxford. “Sustainable Eating Cheaper and Healthier: Oxford Study” (on Springmann M, et al., The Lancet Planetary Health, 2021). November 11, 2021. ox.ac.uk
  14. British Nutrition Foundation. “EAT-Lancet Commission Report Calls for Healthy, Sustainable and Just Food Systems.” October 24, 2025. nutrition.org.uk
  15. WebMD. “Best Diets 2025: Mediterranean Still Tops Rankings” (on U.S. News & World Report’s Best Diets 2025). January 6, 2025. webmd.com