- Vegetarian Diet
- Vegan Diet
- Whole-Food Plant-Based Diet
- Ornish Diet
- Raw Food Diet
- Macrobiotic Diet
- Pescatarian Diet
- Flexitarian Diet
- Pegan Diet
No. 53Vegetarian Diet
A vegetarian eats no meat, poultry or fish. After that, the family tree branches. Lacto-ovo vegetarians eat dairy and eggs; lacto-vegetarians, including many Hindus and Jains, eat dairy but not eggs; ovo-vegetarians eat eggs but not dairy. People choose it for faith, animal welfare, health, cost or the environment, and in India it has been everyday food for many families for centuries.
Strengths
- In the Adventist Health Studies, vegetarians tended to have lower body weight, lower blood pressure and less type 2 diabetes than meat eaters.
- Usually rich in fiber, vegetables, fruit, beans and nuts: most of the produce aisle, invited to dinner.
- Eggs and dairy make protein, calcium and vitamin B12 easier to get than on a vegan diet.
Watch out for
- A "junk-food vegetarian" diet of pizza, chips, pastries and sweets is meat-free, but it isn't healthy. A doughnut is technically vegetarian, too.
- Vitamin B12 can run low if you eat few eggs or little dairy.
- Iron and zinc from plants are absorbed less well than iron and zinc from meat.
- The omega-3 fats EPA and DHA come mainly from fish. Flax and walnuts supply ALA, which the body converts poorly, like a currency exchange with a terrible rate.
- Vitamin D and iodine can be low without sunshine, dairy, eggs or iodized salt.
Eating well within it
- Build meals around beans, lentils, tofu, eggs and yogurt, not just cheese and bread. Cheese is a guest, not the landlord.
- Pair iron-rich foods (lentils, spinach) with vitamin C foods (peppers, citrus), and save tea or coffee for between meals.
- Soak, sprout or ferment grains and beans (sourdough, tempeh, idli) to help your body absorb their minerals.
- Add ground flaxseed or walnuts most days, and use iodized salt at home.
Possible supplement needs
Vitamin B12 and vitamin D come first. Some people also consider an algae-based omega-3, or iron if tests show a need.
Who should be careful
Pregnant or breastfeeding women, children, older adults, and anyone with anemia or a history of disordered eating need careful planning for protein, B12, iron and calcium.
No. 54Vegan Diet
A vegan diet leaves out all animal foods: meat, fish, dairy, eggs, and usually honey and gelatin as well (farewell, gummy bears). The word "vegan" was coined in 1944 by Donald Watson, a founder of the Vegan Society in England. For many it is first an ethical choice about animals, often joined by concern for the environment and for health.
Strengths
- In the Adventist Health Study-2, vegans had the lowest average body weight of the diet groups studied, and vegan groups generally show lower cholesterol.
- High in fiber, beans, vegetables, fruit, nuts and seeds.
- Major dietetic groups, such as the Academy of Nutrition and Dietetics, say well-planned vegan diets can suit people at every stage of life. Notice the word "well-planned"; it is doing a lot of work.
Watch out for
- Vitamin B12 is essential. No plant food is a reliable source, and a shortage can cause anemia and lasting nerve damage. This one is not optional.
- Vitamin D, omega-3 fats (EPA and DHA), iodine, zinc, calcium and iron all need planning. So does protein, especially for athletes and older adults.
- Children, pregnancy and breastfeeding need careful planning; poorly planned vegan diets have caused serious harm in infants.
- Many vegan products (meat substitutes, vegan cheeses, sweets) are ultra-processed, built on refined oils, starches and additives. A leaf on the box does not make it a vegetable.
Eating well within it
- Eat beans, lentils, tofu, tempeh or edamame at most meals for protein, iron and zinc.
- Get calcium from calcium-set tofu, kale, bok choy, tahini and fortified plant milks.
- Choose whole-food fats: avocados, olives, nuts, seeds, and ground flax or chia.
- Keep packaged vegan burgers and desserts occasional: a sometimes food, not a staple.
Possible supplement needs
Vitamin B12 is essential on a vegan diet, from a supplement or fortified foods. Vitamin D, an algae-based omega-3 and iodine are usually needed too.
Who should be careful
Pregnant or breastfeeding women, infants and children, older adults, and anyone with anemia, osteoporosis or a history of eating disorders need careful planning, since shortfalls hit them hardest.
No. 55Whole-Food Plant-Based Diet
A whole-food plant-based (WFPB) diet is built on vegetables, fruit, whole grains, beans, nuts and seeds, eaten close to their natural form, with little or no animal food. If it grew that way, it's in; if a factory reshaped it, probably not. Its leading voices include Dr. Caldwell Esselstyn, a Cleveland Clinic surgeon; Dr. T. Colin Campbell, a nutrition researcher and co-author of The China Study; and Dr. Neal Barnard of the Physicians Committee for Responsible Medicine. The 2011 film Forks Over Knives brought it to a wide audience, and some versions, including Dr. Esselstyn's, allow no added oil at all.
Strengths
- Unlike "vegan" alone, it leaves out processed junk food. Vegan cookies don't get a free pass here.
- Very high in fiber and naturally low in saturated fat; supporters report large drops in cholesterol and weight.
- Dr. Barnard's research group found a low-fat vegan diet improved blood sugar control in people with type 2 diabetes.
Watch out for
- Claims that it reverses heart disease rest mostly on small studies, such as Dr. Esselstyn's own group of patients, not on large randomized trials: encouraging, but not proof.
- The China Study draws on a large observational project in rural China. Critics argue its conclusions about animal protein go further than such data can show.
- Vitamin B12 is essential, as on any vegan diet.
- Strict no-oil versions can be low in calories and hard to sustain. A lifetime of undressed salad is a long road.
Eating well within it
- Fill half the plate with vegetables, a quarter with beans or lentils, and a quarter with intact whole grains or potatoes. Easy math, no app required.
- If you avoid oil, get healthy fat from moderate amounts of nuts, seeds, avocado and olives.
Possible supplement needs
Vitamin B12 is essential. Vitamin D, iodine and an algae-based omega-3 are usually needed too.
Who should be careful
People taking medicine for blood pressure or diabetes: their numbers can fall quickly, so doses may need lowering. Children, pregnant women and anyone underweight need careful planning.
No. 56Ornish Diet
Dr. Dean Ornish, a California physician, developed a program that pairs a very low-fat, mostly vegetarian diet with regular exercise, stress management (such as yoga and meditation) and group support. Think of it as a four-legged stool, not just a menu. The heart-disease version keeps fat to roughly 10 percent of calories, centers on whole plant foods, and allows egg whites and nonfat dairy, with no meat, fish or added oils and little sugar.
Strengths
- In the Lifestyle Heart Trial, published in 1990, people with heart disease who followed the full program showed slight shrinking of artery blockages after one year, while blockages in the usual-care group tended to grow.
- Medicare covers the Ornish program as intensive cardiac rehabilitation for people who qualify after certain heart problems, a sign of mainstream acceptance. When Medicare pays for a diet, it has passed a lot of paperwork.
- It counts stress, movement and connection as just as important as food.
Watch out for
- The trial was small (fewer than 50 people), and because everyone changed several habits at once, it is hard to know how much came from diet alone. It's like asking which oar moved the boat.
- Very low fat is hard to keep up, and it leaves out nuts, olive oil and fish, foods that other research such as PREDIMED supports.
- Vitamin B12 and omega-3 fats can run low.
Eating well within it
- Base meals on beans, whole grains, vegetables and fruit, with egg whites or plain nonfat yogurt if you use them.
- Cook with broth, herbs, garlic and citrus instead of oil. Flavor doesn't have to come out of a bottle.
- Keep the other pillars: a daily walk, a stress practice, and regular time with supportive people.
Possible supplement needs
Vitamin B12, vitamin D and an omega-3 supplement.
Who should be careful
People with heart disease do best in a certified Ornish program, which is built for them. It may not suit anyone who is underweight, pregnant, or has very high calorie needs.
No. 57Raw Food Diet
A raw food diet is made mostly or entirely of uncooked, unprocessed foods, usually plants: fruit, vegetables, nuts, seeds, sprouted grains and beans, and seaweed. The stove gets a long vacation. Many followers aim for at least three-quarters raw, and food may be warmed only to a low temperature (often around 104 to 118°F). Some versions include raw eggs, milk, fish or meat. Early promoters included Swiss doctor Maximilian Bircher-Benner and, later, Ann Wigmore.
Strengths
- Very high in fresh produce, and free of most processed food, added sugar and refined oils.
- Raw foods keep more vitamin C, folate and other heat-sensitive nutrients.
- Most people lose weight, mainly because the food is bulky and low in calories. It is hard to overdo celery.
Watch out for
- Supporters say cooking destroys enzymes the body needs. But plant enzymes are largely broken down in digestion, and the body makes its own, so this claim has little support.
- Cooking makes some nutrients easier to absorb (lycopene in tomatoes, beta-carotene in carrots) and makes beans and grains digestible and safe. The stove is not the enemy.
- Raw sprouts, unpasteurized juice, raw milk, and raw meat or fish can carry harmful bacteria.
- Calories, protein, B12, vitamin D, calcium and zinc often run low. In a German study of long-term raw food eaters, many women were underweight and some stopped having periods.
- Frequent fruit and acidic foods can wear away tooth enamel. Your teeth keep score.
Eating well within it
- Consider "high raw" rather than all raw, adding cooked beans, lentils, whole grains and lightly steamed vegetables.
- Rinse with water after fruit, and wait a while before brushing after acidic foods.
Possible supplement needs
Vitamin B12 is essential on a fully plant-based raw diet. Vitamin D, iodine and calcium are usually needed too.
Who should be careful
Children, pregnant or breastfeeding women, older adults, people with weak immune systems, and anyone underweight or with a past eating disorder should steer clear of a strict raw diet.
No. 58Macrobiotic Diet
Macrobiotics is both a diet and a philosophy, developed by Japanese teacher George Ohsawa in the mid-1900s and spread in the United States by Michio and Aveline Kushi. It aims to balance the yin and yang qualities of food, favoring "centered" foods. The standard plate is mostly whole grains (especially brown rice), plus vegetables, beans, sea vegetables and fermented soy foods like miso, with occasional fish, fruit and seeds; meat, dairy, sugar and most processed foods are avoided. Food is local, seasonal and chewed slowly, so no eating over the sink.
Strengths
- Built on whole grains, vegetables, beans and fermented foods, with very little sugar or processed food.
- Encourages home cooking and slow, mindful meals, the opposite of the drive-through.
- Modern balanced versions look much like traditional Japanese country cooking.
Watch out for
- Strict early versions, especially Ohsawa's stages that narrowed to brown rice alone, led to severe malnutrition and some deaths in the 1960s.
- In Dutch studies, children raised on strict macrobiotic diets had rickets, B12 deficiency and slow growth.
- It is not a cancer cure. Groups such as the American Cancer Society find no evidence for that claim, and using it in place of medical care can be dangerous.
- B12, vitamin D, calcium and iron can run low, and miso, soy sauce and pickles bring a lot of salt along with them.
Eating well within it
- Follow a modern, balanced version with varied vegetables, beans and some fish.
- Get calcium from tofu, leafy greens and sesame seeds or tahini.
- Use sea vegetables in small amounts: a sprinkle, not a salad. Kelp can be very high in iodine, and hijiki can contain arsenic.
Possible supplement needs
Vitamin B12 and vitamin D, especially if little fish is eaten.
Who should be careful
Children, pregnant women, older adults, and people with thyroid conditions should plan carefully. Anyone with cancer or another serious illness should use it only alongside medical care, never instead of it.
No. 59Pescatarian Diet
A pescatarian (or pesco-vegetarian) diet is a vegetarian diet plus fish and seafood: vegetarian with a fishing license. Most pescatarians also eat eggs and dairy. People often choose it as a middle path, easier than full vegetarianism and with the health benefits of fish, while avoiding meat for ethical, environmental or health reasons.
Strengths
- Fish, especially fatty fish, supplies the omega-3 fats EPA and DHA, plus B12, vitamin D, iodine, selenium and high-quality protein. That neatly fills the main gaps of vegetarian diets.
- Eating fish regularly is linked with fewer deaths from heart disease in many studies.
- In the Adventist Health Study-2, pesco-vegetarians had some of the lowest death rates and the lowest colorectal cancer rates of the diet groups studied.
Watch out for
- Large predatory fish (shark, swordfish, king mackerel, tilefish, bigeye tuna) carry the most mercury, which matters most in pregnancy and for young children.
- Fried fish, fish sticks and fast-food fish sandwiches undo much of the benefit. A fish stick is mostly a breading delivery system.
- Overfishing and uneven quality in some farmed and imported seafood are real concerns.
- Like any meatless diet, it can drift toward refined carbs, cheese and snack foods.
Eating well within it
- Eat fish about twice a week, focusing on low-mercury fatty fish: salmon, sardines, anchovies, herring, Atlantic mackerel and trout.
- Bake, grill, poach or steam fish instead of deep-frying it.
- Use canned sardines and salmon with bones for an affordable source of omega-3 and calcium. Yes, the bones: that's where the calcium is.
Possible supplement needs
Usually few if you eat fish twice a week. Vitamin D if sun exposure is low; iron or B12 only if blood tests show a need.
Who should be careful
Pregnant or breastfeeding women and young children should follow official advice on low-mercury fish. People with fish or shellfish allergies, and those eating locally caught fish, should check local advisories.
No. 60Flexitarian Diet
"Flexitarian" blends "flexible" and "vegetarian": mostly plant-based eating, with meat, poultry or fish now and then. Think of it as vegetarian with the door left open. Registered dietitian Dawn Jackson Blatner popularized it in her 2008 book The Flexitarian Diet, which helps people move gradually from a few meatless meals a week toward mostly meatless eating. Nothing is forbidden; the focus is on adding beans, vegetables, fruit, whole grains, nuts and seeds.
Strengths
- Easy to start and to keep, because nothing is banned and it fits family meals, holidays and eating out. No one has to interrogate the waiter.
- Brings many benefits of plant-rich eating (more fiber, less processed meat), while occasional meat, fish and eggs still supply B12, iron and zinc.
- In the Adventist Health Study-2, semi-vegetarians had lower rates of type 2 diabetes than regular meat eaters.
Watch out for
- "Flexible" can get vague; without a plan, many people end up eating much as before, just with a trendier name for it.
- There is little research on the flexitarian plan itself. The evidence comes from plant-rich eating in general.
- Meatless is not automatically healthy. Swapping meat for cheese pizza, white pasta or processed veggie burgers misses the point.
- Any weight loss comes mainly from eating less, and it lasts only if you stick with the changes.
Eating well within it
- Start with set meatless days or meals, then add more as they become habit.
- When you eat meat, choose smaller portions of good-quality, unprocessed meat, poultry or fish rather than bacon and deli meats.
- Build meatless meals around beans, lentils, eggs or tofu.
Possible supplement needs
Usually few. Vitamin D if sun exposure is low; omega-3 if fish rarely makes it to the table; B12 for older adults or anyone eating animal foods only rarely.
Who should be careful
Few people need to avoid it. Those with kidney disease or sensitive digestion may need to adjust their bean and fiber intake.
No. 61Pegan Diet
Dr. Mark Hyman, a functional medicine doctor, coined "pegan" as a blend of paleo and vegan, and set it out in books including The Pegan Diet (2021). Two camps that usually argue at dinner, seated at one table. About three-quarters of the plate is vegetables, mostly non-starchy, with some fruit; meat, poultry, fish and eggs from well-raised sources are a side dish rather than the main event. Nuts, seeds, avocado and olive oil are encouraged; dairy, gluten, other grains and beans are limited; sugar and refined seed oils are avoided.
Strengths
- Puts vegetables at the center and cuts sugar, refined flour and ultra-processed food.
- Offers a middle ground for households split between paleo and plant-based eating. Peace talks, served on a plate.
- Stresses food quality (pasture-raised meat, wild fish, whole foods), much like this book's own approach.
Watch out for
- There are no clinical trials of the pegan diet itself; the evidence comes from studies of its parts.
- Limiting beans and whole grains removes foods that are staples in long-lived populations, such as those in Blue Zones observations.
- Grass-fed meat and wild fish cost more, and your grocery bill will notice.
- The many rules can feel confusing, and very restrictive eating can feed disordered eating in some people.
- Calcium can run low with little dairy.
Eating well within it
- Fill your plate with colorful vegetables, and add a palm-sized portion of fish, eggs or meat.
- If you tolerate them, include lentils, beans and small servings of whole grains like oats, quinoa or black rice, which Dr. Hyman allows in modest amounts.
- Get calcium from canned sardines or salmon with bones, leafy greens, almonds and tahini.
Possible supplement needs
Vitamin D, and calcium if dairy is rare; omega-3 if fish rarely makes it to the table.
Who should be careful
People with kidney disease, those with a history of eating disorders, and people with diabetes, whose blood sugar can change quickly.