Doctors Who Changed Their Thinking
Doctors sometimes change their thinking because of new research. But sometimes the turning point is more personal—an unexpected result in a patient or an experience with their own health.
I find these stories particularly interesting because they show how experience can lead doctors to question what they previously believed.
Nick Norwitz — His Own Illness Changed His Direction
Nick Norwitz developed severe ulcerative colitis while at Dartmouth. Before giving his valedictory address, he was so worried about his symptoms that he fasted beforehand.
His illness worsened while studying for his PhD at Oxford. After conventional treatments failed to give him the improvement he hoped for, he tried a ketogenic diet. Norwitz reports that his symptoms and inflammatory markers improved dramatically and that subsequent biopsies showed remission.
When he graduated from Harvard Medical School, his experience redirected his career toward metabolism, nutrition, ketogenic diets, cholesterol, and brain health.
Eric Westman — Two Patients Changed His Mind
Dr. Eric Westman, an internist at Duke, wasn't looking for a new approach to nutrition.
In 1998, two of his patients came to his clinic after each had lost more than 50 pounds. Westman asked how they had done it.
They had followed the Atkins diet.
Their results surprised him enough that he began investigating low-carbohydrate diets. He visited Dr. Robert Atkins's clinic and eventually conducted his own clinical research at Duke.
More than 25 years later, Westman continues to use low-carbohydrate and ketogenic diets to treat obesity, type 2 diabetes, and other metabolic conditions.
Ken Berry — When His Own Health Changed His Thinking
Dr. Ken Berry, a family physician in Tennessee, spent years giving patients conventional advice about eating less fat, reducing calories, and exercising more.
But Berry himself became obese and prediabetic. He tried following the American Diabetes Association's dietary recommendations and found that his weight and blood sugar did not improve.
That experience made him question what he had learned about nutrition. He began studying low-carbohydrate and ketogenic diets, eventually adopting this approach himself and recommending it to patients.
Berry reports that his own health improved substantially, as did that of many patients. He became an outspoken critic of conventional nutrition advice and wrote Lies My Doctor Told Me.
Today, Berry advocates very-low-carbohydrate eating, including carnivore diets, although the long-term evidence for such restrictive diets remains limited.
His experience as both a physician and a patient fundamentally changed his approach to treating obesity, diabetes, and metabolic disease.
Dr. Berry tells Dr. Peter Brukner how his own struggles with obesity and prediabetes led him to question conventional dietary advice and embrace low-carbohydrate eating. He also discusses how this experience changed his approach to treating patients.
Robert Lustig — Why He Changed His Thinking About Food
Dr. Robert Lustig, a pediatric endocrinologist, became interested in obesity while treating children who gained substantial weight after brain tumors damaged the hypothalamus, which helps regulate appetite and metabolism.
Those patients led him to study insulin, leptin and weight regulation, and eventually the metabolic effects of fructose, added sugar and processed foods.
Lustig came to question whether obesity and metabolic disease could be explained primarily by calories in versus calories out. He argues that what we eat can affect hormones and metabolism in important ways.
Some of his claims about fructose remain debated, but his patients and research clearly changed how he thought about food and metabolic health.
His experience with patients helped change the direction of his research—and ultimately his thinking about food and metabolic health.
Research, articles, books, and videos about metabolic health, sugar, processed food, and nutrition. His website is also cited as his site by professional profiles and interviews.
Lustig explains why he came to focus on insulin and insulin resistance rather than simply calories as drivers of obesity and metabolic disease.
Dr. David Unwin — Rethinking Type 2 Diabetes Treatment
Dr. David Unwin is a British family physician who spent years treating type 2 diabetes using conventional medical advice, including medications and standard dietary recommendations.
His thinking began to change when patients in his practice achieved unexpected improvements by reducing sugar and starchy carbohydrates.
Unwin became interested in how foods such as bread, rice, potatoes, and breakfast cereals affect blood glucose. He began encouraging interested patients to try a lower-carbohydrate diet, emphasizing real foods and reducing refined carbohydrates.
The results surprised him. Many patients experienced improvements in blood glucose, weight, and other metabolic markers. Some were able to reduce medications, and others achieved remission of type 2 diabetes.
Dr. Unwin and colleagues subsequently published findings from their medical practice documenting these improvements. Although these were observational results rather than randomized clinical trials, they demonstrated what could be achieved in everyday primary care.
What changed his thinking? Seeing patients improve with a dietary approach that differed from the advice he had traditionally given.
His experience raises an important question: Should reducing carbohydrates play a larger role in treating type 2 diabetes, potentially before adding more medications?
A 2023 study of 186 patients following a low-carbohydrate approach. After an average of 33 months, 51% achieved drug-free remission. Among patients who began within a year of diagnosis, the remission rate was 77%. These were observational findings, not a randomized trial.
Unwin describes how a patient's question in 2012 led him to reconsider 26 years of conventional dietary advice. An interesting firsthand account of what changed his thinking.