No diet has been shown to make any one person live longer. What research does show is that people who eat Mediterranean-style, plant-forward and other high-quality patterns have lower death rates over decades of follow-up, and that a two-year calorie-restriction trial changed several health markers without measuring lifespan. Here is what those studies measured, and where their limits are.
Key Takeaways
- In a Harvard-led study of about 119,000 adults followed for up to 36 years, the highest scores on four different healthy eating patterns were linked to roughly 14% to 20% lower risk of death over the study period.
- A 2023 meta-analysis of 16 cohort studies in more than 720,000 women linked high Mediterranean diet adherence with 23% lower total mortality.
- The CALERIE trial cut calories by about 12% for two years in healthy adults of normal or slightly above-normal weight. Several risk markers improved, bone density dipped slightly, and lifespan was not measured.
- "Blue Zones" are a source of ideas, not proof. A 2025 review found only three of the regions are well characterized, and no studies have been done in Loma Linda.
- Older adults may need more protein than younger adults. An expert group suggests at least 1.0 to 1.2 g per kilogram of body weight a day after age 65.
- Diet works alongside not smoking, physical activity and body weight. In one large analysis, the five habits together were linked with 12 to 14 more projected years of life at age 50.
Evidence grade: Moderate. Very large prospective cohorts consistently link healthy eating patterns with lower death rates, and one large randomized trial supports a Mediterranean diet for cardiovascular events, but no trial has measured human lifespan.
How Researchers Study Diet and Longevity
Lifespan is hard to test directly. A randomized trial would have to assign people to diets for decades and then wait. So most of the evidence comes from three kinds of research:
- Prospective cohort studies record what tens of thousands of people eat and follow them for years. They are powerful but observational. People who eat well also tend to smoke less and move more, and researchers can only partly adjust for that.
- Randomized trials assign diets and measure events or risk markers over a few years. They are better at showing cause and effect, but they rarely measure lifespan.
- Studies of long-lived populations describe how people live in regions with many very old residents. They generate ideas but cannot separate diet from genes, climate, community and history.
Words like "linked to" and "associated with" usually signal cohort research. Keep that in mind as you read headlines.
More Than One Healthy Eating Pattern
There is no single "longevity diet." In a 2023 study in JAMA Internal Medicine, researchers followed 75,230 women from the Nurses' Health Study and 44,085 men from the Health Professionals Follow-up Study for up to 36 years. They scored each person's diet on four patterns.
| Eating pattern score | What it rewards | Risk of death, highest vs lowest scores |
|---|---|---|
| Healthy Eating Index 2015 | Alignment with the Dietary Guidelines for Americans | 19% lower (HR 0.81) |
| Alternate Mediterranean Diet | Vegetables, fruits, legumes, nuts, whole grains, fish and olive oil | 18% lower (HR 0.82) |
| Healthful Plant-based Diet Index | Healthy plant foods over refined plant foods and animal foods | 14% lower (HR 0.86) |
| Alternate Healthy Eating Index | Foods and nutrients tied to lower chronic disease risk | 20% lower (HR 0.80) |
All four scores were also linked with lower death rates from cardiovascular disease, cancer and respiratory disease, and the associations held across racial and ethnic groups. Because diet was measured by questionnaire and the design was observational, the study cannot prove the diets caused the difference. Its practical message is that several flexible patterns built on the same core foods point in the same direction. For everyday guidance, see our overview of a healthy diet.
The Mediterranean Pattern
The Mediterranean pattern is the most studied of these. It centers on vegetables, fruit, legumes, nuts, whole grains, fish and olive oil, with less red and processed meat.
What the trial measured
PREDIMED, a Spanish trial of 7,447 adults aged 55 to 80 at high cardiovascular risk, compared a Mediterranean diet with extra olive oil or with nuts against advice to cut dietary fat. The original 2013 report was withdrawn after randomization problems were found at some sites. In the 2018 reanalysis, major cardiovascular events (heart attack, stroke or cardiovascular death) were about 30% lower in the two Mediterranean groups, with hazard ratios of 0.69 and 0.72. The trial measured events over a median of 4.8 years, not lifespan.
What the cohorts measured
A 2023 meta-analysis in Heart pooled 16 prospective cohort studies of 722,495 women. Higher adherence to a Mediterranean diet was associated with 24% lower cardiovascular disease incidence and 23% lower total mortality. Our guide to what the Mediterranean diet is covers the foods in more detail.
Plant-Forward Eating
Plant-forward does not have to mean vegan. The Adventist Health Study 2 followed 73,308 Seventh-day Adventists for an average of 5.8 years. After adjustment, vegetarians as a group had 12% lower all-cause mortality than non-vegetarians (HR 0.88). Pesco-vegetarians, who ate fish, had the lowest estimate (HR 0.81). The associations were larger and more consistent in men than in women.
Diet was measured once at the start, follow-up was short, and a single religious community may differ from the general population in ways that are hard to adjust for. The finding fits the wider research rather than proving that cutting out meat lengthens life.
Calorie Restriction: What the CALERIE Trial Measured
Calorie restriction means eating fewer calories than usual without becoming malnourished. In many animal experiments, from worms to rodents, it delayed age-related problems and in some studies extended lifespan. Popular articles often quote large lifespan gains in mice and rats, but animal results do not transfer directly to people.
Primate data are mixed. Two long-running rhesus monkey studies started in the 1980s: the University of Wisconsin study reported a survival benefit, while the National Institute on Aging study did not. A joint 2017 analysis concluded that the health benefits of calorie restriction are conserved in monkeys, and pointed to differences in study design, diet and the age when restriction began.
The best human evidence is CALERIE, an NIA-supported trial that randomized 218 healthy, non-obese adults aged 21 to 51 to a 25% calorie cut or their usual diet for two years.
- Participants did not reach 25%. They averaged about a 12% cut and kept off about 10% of body weight.
- Compared with controls, the restriction group had lower LDL cholesterol, blood pressure and other cardiometabolic risk markers, and decreases in some inflammatory markers and thyroid hormones.
- Quality of life, mood and sleep were not harmed.
- There were slight declines in bone density, lean mass and aerobic capacity, and some participants had brief episodes of anemia.
- Lifespan was not measured. The NIA states that there are no human data on calorie restriction and longevity, and that there is not enough evidence to recommend such regimens to the public.
For time-based eating patterns, which are a different approach, see our article on the benefits of intermittent fasting.
Blue Zones, Described Carefully
"Blue Zones" is a popular label for regions said to have unusually many centenarians. A 2025 scoping review in Aging and Disease searched the scientific literature on every region that authors had called a Blue Zone and found 65 records covering ten regions. Its conclusions:
- Ogliastra (Sardinia), Okinawa and Nicoya (Costa Rica) showed higher longevity than their national averages and were the only regions it called well characterized.
- Ikaria (Greece) and Cilento (Italy) showed high life expectancy. Data from Menorca were inconclusive, and Rugao in China had fewer centenarians.
- No studies had been conducted in Loma Linda, California, which is often listed as a Blue Zone.
- Factors linked with longevity in these places included diet, physical activity, climate, genetics and geographic isolation.
Traditional diets in the best-studied regions tend to be plant-heavy, which is consistent with the cohort research above. But these regions cannot isolate diet from everything else about how people live. Our article on the dietary habits of the world's oldest people looks at those traditions.
Protein Needs After 65
Eating less is not the goal for most older adults. The PROT-AGE Study Group, convened with the European Union Geriatric Medicine Society, concluded that older adults need more dietary protein than younger adults to maintain muscle and function. It recommends:
- At least 1.0 to 1.2 g of protein per kilogram of body weight a day for adults over 65. For a 70 kg (154 lb) adult, that is about 70 to 84 g a day.
- 1.2 g/kg or more for those who exercise or are otherwise active, alongside endurance and resistance exercise at safe levels.
- 1.2 to 1.5 g/kg for most older adults with acute or chronic illness.
- An exception for people with severe kidney disease who are not on dialysis, who may need to limit protein.
The group noted that evidence on protein timing and quality was not yet strong enough for specific advice. For more on eating well later in life, see our guide to nutrition for healthy aging.
Diet Is One Factor Among Several
A 2018 analysis in Circulation used data from more than 120,000 US health professionals followed for up to 34 years. It looked at five low-risk habits: never smoking, a body mass index of 18.5 to 24.9, at least 30 minutes a day of moderate to vigorous activity, moderate alcohol intake and a diet score in the top 40%. Compared with adopting none, adopting all five was linked with a projected 14 more years of life expectancy at age 50 for women and about 12 more for men.
These are population estimates based on self-reported habits, not a forecast for any individual. They show that food sits alongside smoking, activity and weight, not in place of them.
Putting the Research on Your Plate
Across these studies, the patterns linked with lower death rates share a common core:
- Vegetables and fruit at most meals
- Beans, lentils and other legumes several times a week
- Whole grains in place of refined grains
- Nuts and olive oil as regular fat sources
- Fish more often than red or processed meat
- Enough protein spread through the day, especially after 65
Pick the version that fits your culture and tastes, because the research suggests several versions point the same way.
Safety and Interactions
Changing to a Mediterranean or plant-forward pattern is generally low risk, but deliberate calorie restriction is different. In CALERIE, bone density and lean mass fell slightly and some participants had brief anemia, and the investigators advised close monitoring. The NIA notes that scientists still do not know whether calorie restriction is safe or practical over the long term, including for older adults.
- Talk to your doctor before cutting calories if you are an older adult, are underweight, are pregnant or breastfeeding, or have a history of disordered eating.
- If you have kidney disease, ask your doctor before increasing protein; PROT-AGE makes an exception for severe kidney disease not treated with dialysis.
- If you take medicines for blood sugar, blood pressure or blood clotting, talk to your doctor or pharmacist before making a large change in what or how much you eat.
Frequently Asked Questions
Is there a diet that makes you live longer?
No diet has been proven to extend an individual's life. Large cohort studies link Mediterranean-style, plant-forward and other high-quality patterns with lower death rates, but they show associations, not guarantees, and diet works alongside activity and not smoking.
Does calorie restriction extend human lifespan?
That has not been shown. The two-year CALERIE trial improved several cardiometabolic risk markers but also caused small losses in bone density and lean mass, and it did not measure lifespan. The NIA says there is not enough evidence to recommend calorie restriction to the public.
Are Blue Zones real?
A 2025 scoping review found that Ogliastra in Sardinia, Okinawa and Nicoya are well characterized as high-longevity regions, while other regions remain under investigation and Loma Linda has no published studies. Diet in these places cannot be separated from genetics, activity, climate and isolation.
Do vegetarians live longer?
In the Adventist Health Study 2, vegetarians had 12% lower all-cause mortality than non-vegetarians over about six years, with clearer results in men. The study was observational and the community may differ from the general population in other ways.
Is it too late to change my diet after 60?
The core foods in these patterns are the same at any age. Older adults should be careful not to lose muscle or weight unintentionally, so the focus is usually adding vegetables, legumes, whole grains and enough protein rather than cutting calories. Check with a doctor or dietitian first.
How much protein do older adults need?
The PROT-AGE Study Group recommends at least 1.0 to 1.2 g per kilogram of body weight a day for adults over 65, and more for active people or those with illness. People with severe kidney disease not on dialysis may need less, so ask your doctor.
Sources
- National Institute on Aging. Calorie restriction and fasting diets: What do we know? NIH. 2023.
- Ravussin E, Redman LM, Rochon J, et al. A 2-year randomized controlled trial of human caloric restriction: feasibility and effects on predictors of health span and longevity. J Gerontol A Biol Sci Med Sci. 2015.
- Kraus WE, Bhapkar M, Huffman KM, et al. 2 years of calorie restriction and cardiometabolic risk (CALERIE): exploratory outcomes of a multicentre, phase 2, randomised controlled trial. Lancet Diabetes Endocrinol. 2019.
- Mattison JA, Colman RJ, Beasley TM, et al. Caloric restriction improves health and survival of rhesus monkeys. Nat Commun. 2017.
- Shan Z, Wang F, Li Y, et al. Healthy eating patterns and risk of total and cause-specific mortality. JAMA Intern Med. 2023.
- Pant A, Gribbin S, McIntyre D, et al. Primary prevention of cardiovascular disease in women with a Mediterranean diet: systematic review and meta-analysis. Heart. 2023.
- Estruch R, Ros E, Salas-Salvado J, et al. Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts. N Engl J Med. 2018.
- Orlich MJ, Singh PN, Sabate J, et al. Vegetarian dietary patterns and mortality in Adventist Health Study 2. JAMA Intern Med. 2013.
- Li Y, Pan A, Wang DD, et al. Impact of healthy lifestyle factors on life expectancies in the US population. Circulation. 2018.
- Candal-Pedreira C, Rey-Brandariz J, Martin-Gisbert L, et al. Blue Zones, an analysis of existing evidence through a scoping review. Aging Dis. 2025.
- Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013.
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
