Dr. John McDougall, a renowned physician known for his stance on preventative medicine through adopting a whole foods, plant-based diet, published a study demonstrating the efficacy of this diet. In an article titled, “Effects of 7 days on an ad libitum low-fat vegan diet: The McDougall Program cohort,” 1,615 participants, many of whom were overweight and had a history of illnesses such as diabetes, hypertension, and cardiovascular disease, participated in a physician-monitored 10-day residential program. The participants were fed three meals a day that aligned with Dr. McDougall’s guidelines. All meals were served buffet-style and were based on complex carbohydrates such as rice, quinoa, oats, potatoes, sweet potatoes, and beans, with the addition of vegetables and fresh fruits. Such foods were strictly prepared without oil or animals-derived ingredients (meat, dairy, eggs). Minimal sugars and salts were used in the form of condiments. The macronutrients of Dr. McDougall’s diet regime are strictly less than 10% of daily calories from fat, 10% calories from plant-based protein, and 80% of calories from high-fiber carbohydrates in the form of whole starches.
The program included a cohort of educational staff: a medical doctor (McDougall himself), a registered dietitian, a psychologist, exercise coaches, and cooking instructors, all of whom supervised the the participants, who were allowed to eat “ad libitum” (i.e., as much as they wanted with no restrictions) until satiated. On the first day of the program, all participants underwent a physical examination and their baselines levels were recorded for the following biomarkers: weight, blood pressure, total cholesterol, triglycerides, glucose, blood urea nitrogen, and creatinine. These measurements were recorded again on the seventh day of the program. These biomarkers were recorded again on the seventh day, and differences in values were analyzed to see if there were measurable reductions in health risks for the participants. These risks were assessed using The American College of Cardiology and the American Heart Association published guidelines for predicting a patient’s risk of developing atherosclerotic cardiovascular disease (ASCVD) within 10 years. Such a risk could be predicted only if the patient has the relevant factors of age, HDL cholesterol, systolic blood pressure, smoking status, diabetes, and high blood pressure. ASCVD risks were calculated twice for the patients who fell under all the relevant factors, once on the first day as part of their baseline values, and again on the seventh day.
On the seventh day of the program, participants saw a statistically significant decrease in average cholesterol, weight, blood pressure, blood glucose, creatinine, and blood urea nitrogen. Those who were the most overweight had the highest numbers for their baseline biomarkers, and saw a greater decrease in their numbers compared to participants whose baselines were in a healthy range. The median weight loss was 1.4 kg (3 pounds) in only seven days. The risk for ASCVD was reduced by an average of 2.00 percentage points among patients whose risk was elevated on the first day, as opposed to the general sample where the risk was reduced by 1.00 percentage points. Despite some limitations in the study, McDougall’s intensive, residential educational program demonstrates a potential low-cost approach to healthcare. A change from an animal-based to a plant-based diet improves people’s health in the short term and possibly long term. Most importantly, it bypasses expensive, current approaches to medicine such as prescription medication and major surgery.