According to the latest National Health and Nutrition Examination Survey (NHANES) and CDC data, the prevalence of obesity in the U.S. is 39.8% in adults and 18.5% in children with 20.6% of adolescents classified as obese. Obesity costs the U.S. more than $147 billion annually, and the U.S. is the #1 OECD country in obesity. For diabetes mellitus type 2, the U.S. prevalence is 9.4% with an annual incidence of 1.5 million. Additionally, 84.1 million U.S. adults have pre-diabetes. Diabetes costs the U.S. $327 billion annually. Together, diabetes and obesity cost 14% of the total U.S. healthcare spending of $3.5 trillion last year. Both diseases are predominantly acquired, preventable conditions due to lifestyle.

Pharmaceuticals, particularly for diabetes, are released annually, but the medical and economic effects of these chronic diseases persist with little improvement because these pharmaceuticals don’t treat the underlying cause — diet. Patients are confused and wonder what to do when their physician or dietitian tells them to eat “healthy.” Physicians have not been, and still aren’t, taught any nutrition in medical school or residency. The result is one of three common, reactionary responses from the medical community. They prescribe medications with side effects that then require additional medications. They perform bariatric surgery, the most drastic option in all but the most extreme cases, which nevertheless does nothing to treat the underlying cause. Or, they tell patients to “manage” their conditions for their entire lives, meaning suffering through complications, drug side effects, depression, etc., again without treating the underlying cause of poor dietary choices. Physicians tell patients to eat eggs or meat like “lean” or “farm-raised” beef or pork, which just fuels further insulin resistance (caused by lipotoxicity, not sugar)[1], weight, chronic inflammation, and dyslipidemia.

A little diet science.

When we look at historical evidence and examine global populations who are healthy, live the longest, and are the most functional in later years, there is one common theme: their diet is vastly different than ours in the U.S. Furthermore, no population in the history of the world that lived long, healthy lives either in the past or currently ever followed a low-carbohydrate diet like Atkins or South Beach. When one looks at Blue Zones[2],[3] regions of the world (only one of which exists in the U.S.), all eat a mostly plant-based diet with infrequent meat intake, little to no dairy, real whole grains (meaning all 3 parts of the grain not “multi”, “ancient”, “seven” -grain, or other misleading terminology in the ingredients section), and beans/lentils/legumes almost daily, if not daily[4].

The key is a reasonable amount of naturally-occurring, unprocessed carbohydrates, specifically from a variety of source plant materials. Additionally, plant-sourced foods provide more than enough protein. In fact, research in the U.S. back in the 1960s showed how much protein the average man and woman needs per day: the maximum is around 60 grams for 70-kg men and 50 for 60-kg women[5],[6],[7],[8]. Research also showed that eating a variety of plant-based foods, even exclusively, will supply all 9 essential amino acids (the other 11 made endogenously)[9],[10],[11]. We now eat too much protein (90 grams/day or more) with no benefit and some risk[12],[13],[14]. First, through a series of pathways, excess intake of protein gets indirectly turned to fat and prevents the burning of fat already present. Next, it overtaxes the liver and the kidneys in the processing of excess protein and then secretion and partial reabsorption in the glomerular filtration system.

Even though low-carb, high-protein diets result in switching the metabolism to ketosis, which burns fat, that is not sustainable long term and causes problems with lipid metabolism and hepatic and renal health[15],[16]. Blue Zone populations never followed such diets, yet they live long and are functional in their 9th and 10th decades of life. They also have the highest rates of centenarians. It’s not genetics. Numerous studies over decades show that individuals from those populations develop common Western ailments when they adopt local diets. Physical activity and stress management are important, indeed, but research shows diet is far more so.

Regarding Paleo diets, archaeological evidence shows that Paleolithic humans did not eat what modern people think they ate. Furthermore, the plants and animals that we consume now were very different than those in Paleolithic times. Experts in Stone Age nutrition think our ancestors — who, by the way, were foragers — consumed a wide variety of ever-changing plant foods that gave them up to 100 grams of fiber daily. We, on the other hand, eat an average of 15 grams of daily fiber. Our forebears are thought to have eaten lots of insects, too. (Few people espousing the virtues of “Paleo” seem inclined to try that out.) They probably ate grains, with some evidence they did so 100,000 years or more ago. And, of course, they ate the meat of only wild animals, since there were no domesticated animals in the Stone Age, apart from the wolf-to-dog transition. They also did not live very long for various reasons, so it makes no sense to emulate their diets for longevity reasons. In any event, the plant-predominant diet to which we are adapted to is almost certainly much better for health and reversing illness than the prevailing modern diet. There is abundant evidence of disease-reversal with diets of whole, minimally processed food; plant-predominant diets; and even plant-exclusive diets[17].

What should our patients eat?

So, what should we ourselves eat (as role models for patients) and advise our patients to eat?

Eliminating all animal products is ideal, but not necessary. However, research has shown that animal proteins and saturated fat immediately cause vasoconstriction; increase and persistence of low-grade chronic inflammation; negative effects on fecal microbiota, which recent research has shown is vital in modulating many biochemical and metabolic pathways, particularly in prevention and control of many metabolic diseases and some cancers; and lipid dysmetabolism[18]. Family history or genetics is not the culprit. At most, the effect of genetics or family history (in the absence of specific familial mutations) is responsible for 10% of chronic diseases with notable environment-caused epigenetic and gut microbiota effects, not direct genetic effects[19]. The rest of our health outcome is based on our lifestyle choices. Because cholesterol only exists in animal cells, if you eat mostly or exclusively plants, you take in far less exogenous cholesterol. If you consume plants, you cannot get trans saturated fats, even from the maligned coconut oil. Multiple studies have shown that saturated fat from plant foods like nuts, avocado, and coconuts does not cause negative metabolic effects in humans the same way saturated fat from meat, fish, poultry, eggs, and dairy does. Proteins from plants do not cause inflammation the way proteins from animal products do [17].

Heme iron from red meat may cause a quicker increase in blood iron levels but it also causes inflammation and restricts the absorption of other beneficial nutrients. Non-heme iron from sources like spinach causes no inflammation; for maintenance of normal iron levels, daily consumption of dark-green, leafy vegetables will supply enough iron plus no cholesterol, saturated fat, or pro-inflammatory mediators [13,17].

What about vitamin D and calcium? First, there is plenty of calcium in vegetable sources without the fat, cholesterol, hormones and antibiotics (if factory-farmed), pus/infection from the animal (if not pasteurized well, which is a minimum of 15 seconds in the U.S. at 72°C and only 1 second in Canada by their respective national laws), and realization that we are the only creatures on Earth that consume another species milk (cow’s milk is much higher in saturated fat than human milk for example). In fact, kale has more calcium than milk by weight. For vitamin D, non-animal sources include mushrooms, fortified cereals and plant milks, supplements, and, of course, the sun. Lastly, B12. B12 is only available in animal products except for nutritional yeast and fortified plant milks so for vegans, this must be supplemented. Vitamin B12 may become increasingly difficult to absorb as we age, which is why the government recommends we supplement with this nutrient after the age of 50.

Let’s not forget the dearth of fiber intake in this country. About 97% of Americans do not consume the U.S.-recommended dietary allowance of fiber. This directly affects development and worsening of chronic disease. Fiber is also satiating. There is emerging evidence that fiber supports a healthy gut microbiome and, for patients with type 2 diabetes, can keep blood sugar and weight under control [20].

So, we should tell patients they can meet all requirements for protein, vitamins, minerals, essential fats, etc. by eating a whole-plant, whole-grain diet with beans/lentils/pulses and nuts/seeds (if not allergic). At the same time, they’ll avoid the harmful intake of cholesterol, pro-inflammatory animal proteins and saturated fats, as well as excess sodium. They’ll see decreased weight, decreased blood pressure, improved glucose metabolism, more energy, and more alertness.

Is it possible for Americans to switch to a mostly plant-based diet?

Yes! In most parts of the country, varieties of fruits, vegetables, whole grains, beans, nuts, and seeds are available. Unfortunately, I have seen many areas — rural and urban — that are true food deserts where 10% of the grocery store is devoted to produce, 50% to meat, and the rest to packaged and processed foods. However, in some of those same places, I’ve seen farmer’s markets within a few miles of such “grocery” stores, as well as individual and community farming, and small neighborhood niche stores specializing in healthier options. As a vegan working many days to weeks in those places, I was able to find appropriate food options most of the time.

The cost of eating better is also not a factor as it once was. Analyses of local cost comparisons in multiple cities shows that people can save money by doing things like buying a large bag of rice or dry beans, fresh vegetables, and frozen fruits and vegetables (which are just as healthy as fresh fruits and vegetables)[21],[22]. The argument I hear frequently from other physicians is that patients can’t afford to eat healthier. This fails to address patients’ needs and the consequences of chronic illnesses medically, emotionally, and financially. It also isn’t true. Research indicates that a healthy, plant-predominant diet is significantly cheaper than a meat-centered diet.

I also hear from physicians that, while they agree with me on counseling patients to eat more plant-based products (thereby crowding out unhealthy and unnecessary processed and meat products), patients just won’t do that. That argument is paternalistic and echoes excuses physicians in the 1950s made about tobacco cessation counseling despite numerous studies and, ultimately, the Surgeon General’s report on the dire medical harms of tobacco smoking.

Lastly, there are frequently questions about taste of food, especially plant-based or “fake” meat/dairy products despite many vendors and recipes now available. The best option to recommend to patients is that they strive to eat minimally-processed foods, not highly-processed, plant-based versions of meat and dairy. Similarly, when one speaks to patients about reducing salt intake, patients often push back due to taste. However, research has shown that it takes only 60 days or so (often far less) for one’s taste to change, particularly for salt[23]. Once patients get used to low-salt items, the typical amount of salt in American diets is no longer palatable. Nothing happens overnight, but changes do occur! In fact, as a hospitalist, I introduce this and overall dietary changes to my patients while they’re recovering from a cardiac or diabetic event or complication. It’s an ideal time to grab their interest and then seek out more information starting with sources I recommend to them[24].

The U.S. cannot prescribe our way to health. It doesn’t work. We have some of the world’s highest rates of chronic disease yet spend the most on medical care. It’s time for the U.S. to take the lead in lifestyle medicine, particularly plant-based diets, in the same way we have become leaders in prescription-based medicine — to the much greater benefit of our patients and our national healthcare budget!

Ankush K. Bansal is a hospitalist, board certified in internal medicine based in south Florida. He was also part of the first cohort to take and pass the certification exam in Lifestyle Medicine by the American and International Boards of Lifestyle Medicine. He advises patients who are suffering from the complications of their chronic illnesses on diet while doing hospital rounds.

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Published online 2016 Apr 22. doi: 10.1371/journal.pone.0154387

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