The new research shows that the story is much more complicated.
A big study of very old people found that people who eat meat are more likely to live to be 100 than people who don’t eat meat at all. But the results are more about body weight, frailty, and how nutritional needs change as people get very old than a simple comparison of meat and plants.
What the study really found
The study utilized data from over 5,000 Chinese adults aged 80 and older, monitored through the extensive Chinese Longitudinal Healthy Longevity Survey from 1998 to 2018.
Scientists looked at people who ate meat and people who didn’t eat meat. Researchers found that people who didn’t eat meat were less likely to live to be 100 years old.
Among very old adults, those who refrained from meat were less likely to attain the age of 100, but solely if they were already underweight.
When researchers divided the participants based on body weight, a significant detail emerged. The lower chance of reaching 100 was only seen in older adults who were underweight and didn’t eat meat. In older adults with a healthy weight, diets without meat did not appear to reduce lifespan.
People who ate fish, eggs, or dairy but not meat also did just as well as people who ate meat when it came to reaching 100.
Why this doesn’t undo decades of research on plants
The results seem to be a new twist in the diet debate at first glance. For years, studies have shown that diets that are mostly plants or vegetarian are less likely to cause heart disease, stroke, type 2 diabetes, and obesity. Higher fiber, lower saturated fat, and a wider range of vitamins and plant compounds are often linked to these benefits.
This new study looks at a very different group: adults who are already in their 80s or older. Most of the research that has been done on vegetarian and vegan diets has been on adults who are middle-aged or younger and are generally healthy, so they have a lot of time before diseases start to show up.
The diet that keeps you healthy at 45 may not be the same one that keeps you healthy at 90.
When you get very old, your priorities change. Staying strong, keeping your weight in check, and avoiding frailty are more important than lowering your risk of long-term disease. That can change the best balance of plant and animal foods for the body.
How your dietary needs change after 80
Our bodies start to process food differently when we reach our seventh or eighth decade of life. Older people tend to move less, burn fewer calories, and sometimes lose their appetite. Sarcopenia and osteoporosis are two conditions that cause muscle and bone mass to decrease. This makes the risk of malnutrition higher.
Energy needs go down, but needs for some nutrients stay the same or go up. These are:
Protein helps keep muscles strong and the immune system working.
Calcium helps bones stay strong and lowers the risk of breaking them.
Vitamin D helps muscles and helps the body absorb calcium.
Vitamin B12 is good for the nervous system and red blood cells.
Meat, fish, eggs, and dairy are all good sources of these nutrients. A well-planned plant-based diet can give most of them, but for very old adults who are already eating less, every bite has to work harder.
That could be why the study found that non-meat eaters who were underweight did worse. If you are thin, weak, and not eating much, cutting out foods that are high in energy and protein can make you more likely to be undernourished.
The “obesity paradox” and how body weight plays a role
Being underweight later in life is strongly linked to a higher risk of death. It usually means that you have an illness, don’t want to eat, or are losing muscle. In the study, low body weight appeared to be the primary warning indicator rather than the mere absence of meat.
The study corroborates the “obesity paradox,” which posits that a marginally elevated weight frequently correlates with enhanced longevity in older adults.
Too much body fat is usually bad for younger and middle-aged adults. For older people, a little extra weight can be helpful when they are sick, in the hospital, or not feeling hungry. On the other hand, very low weight doesn’t leave much room for setbacks.
A strict, low-calorie, low-protein diet might look good on paper for an 85-year-old who is underweight, but it could be dangerous in real life.
Why fish, eggs, and dairy make a difference
A fascinating aspect of the study involved the cohort of older adults who abstained from meat consumption yet included fish, eggs, or dairy in their diet. These people had the same chances of living to be 100 as the people who ate meat.
These “flexible” diets still limit red and processed meat, which are often blamed for a higher risk of heart disease and bowel cancer. However, they do include animal-source foods that are high in protein, B12, calcium, and vitamin D. That mix might help keep bones and muscles strong without completely giving up on eating plants.
Group of foodImportant nutrients for older adults
MeatProtein, iron, vitamin B12, and zinc of high quality
FishVitamin D, B12, protein, and omega-3 fats
EggsVitamin D (in some cases), choline, B12, and protein
DairyFortified foods with protein, calcium, and vitamin D
Tofu, lentils, and beansPlant protein, fiber, iron (non-heme), and magnesium
What this means for staying healthy as you get older
The researchers emphasize that their study is observational. They can show connections, but they can’t show that not eating meat directly lowers the chance of reaching 100. People who don’t eat meat may also be different in other ways, such as how much money they make, how easy it is for them to get healthcare, how much they go to school, how active they are, or how many times they’ve been sick in the past.
The results, however, point to an important point: diets should change as you get older. At 40, the “perfect” diet isn’t always the best one at 85.
For very old adults, keeping their muscles and avoiding weight loss may be more important than cutting every gram of fat.
Plant-based diets can definitely help you age well, but you might need to plan them out more carefully as you get older. That could mean bigger servings of beans, lentils, soy products like tofu and tempeh, fortified plant milks, and sometimes B12 or vitamin D supplements that a doctor says are needed.
Practical examples: people in their 80s who eat meat, are vegetarians, or are vegans
If an older person eats meat
The study does not indicate that an individual in their 80s who already consumes meat should hasten towards veganism. A more realistic change might be:
Choosing smaller amounts of red and processed meat
Changing some meat meals for fish, beans, or lentils
Putting more whole grains, vegetables, and fruit around the meat
This keeps protein and B12 levels high while lowering the risks of heart disease and cancer that come with eating a lot of red and processed meat.
If an older person doesn’t eat meat
For very old vegetarians or vegans who have been doing it for a long time, the message is not “start eating steak.” Instead, the focus is on blood tests, weight, and strength:
Keeping an eye on body weight and losing weight without meaning to
Adding foods high in protein to every meal, like beans, lentils, soy, and nuts
Seeing a doctor to check your levels of B12, vitamin D, and iron
Taking fortified foods or supplements when told to
If a person is underweight, weak, and having trouble getting enough food, doctors or dietitians might gently suggest foods that are high in calories and protein. For some older people, that could mean eggs, dairy, or fish, depending on their health and beliefs.
Important terms to make clear
Centenarian: Someone who has lived to be at least 100 years old. Researchers often look for patterns in the lifestyles, diets, genetics, and social factors of centenarians that might help them live longer.
Frailty is a clinical condition characterized by weakness, reduced walking speed, diminished physical activity, and weight loss. People who are frail are more likely to get infections, fall, and have problems after surgery or a hospital stay.
Sarcopenia is the loss of muscle mass and strength that happens with age. Higher protein intake, resistance exercises and adequate vitamin D can slow this decline.
Risks, trade-offs and long-term habits
Choosing how much meat to eat is never just a question of lifespan. There are ethical, environmental and cultural factors, along with varying health risks across life stages. A diet that keeps cholesterol low for decades still needs enough fuel in old age to prevent frailty.
One practical way to think about it is as a long game: a plant-forward pattern from mid-life to reduce heart disease and diabetes, with flexibility later on to protect strength and weight. That flexibility might mean slightly more animal-source foods for some older adults, or more deliberate use of fortified plant foods and supplements for others.
The new study doesn’t hand victory to meat or plants. Instead, it quietly suggests that longevity isn’t about a single rule, but about how well your diet matches your age, your body and your health at each stage of life.
