Obesity is defined by the Mayo Clinic as having an excessive amount of body fat. Specifically, “Obesity is diagnosed when your body mass index (BMI) is 30 or higher.” [1] To understand the immense scale of this issue it’s important to review some numbers. According to the United States National Center for Health Statistics, the percent of adults aged 20 and over with obesity is about 40%. Also staggeringly large is the percentage of adults aged 20 and over that are either overweight or obese, which is 71.6% [2] If the current trend continues, almost 100% of Americans will be obese by the end of the century. [3]

Not only does the obesity epidemic affect the majority of American adults, but it also prevalent in children. Over 1 in 5 adolescents aged 12-19 years have obesity. Overall, 18.5% of youth have obesity. The fact that such a large proportion of our population suffers from being obese and overweight means that this problem is of utmost importance and urgent action is needed.

Adult Obesity Prevalence Map of the US by state. Based on Self-Reported Obesity data Among U.S. Adults by State and Territory, BRFSS, 2017 Source: Behavioral Risk Factor Surveillance System

However, being overweight or obese is not an irreversible condition. Dr. Walter Kempner, the father of modern-day diet therapy, first introduced his dietary program to treat chronic kidney disease in 1939. His treatment consisted of white rice, fruit, juice, and sugar. However, the benefits of the diet surpass any drug or surgery ever prescribed for conditions such as coronary artery disease, heart and kidney failure, hypertension, diabetes, arthritis, and obesity. [4,5,6]

This image shows the results of Dr. Kempner’s rice diet.

Dr. Kempner then published an analysis of 106 patients who each lost at least 100 pounds. He wrote, “This study demonstrates that massively obese persons can achieve marked weight reduction, even normalization of weight, without hospitalization, surgery, or pharmacologic intervention.” [7] However, even Dr. Kempner himself considered the rice diet pretty drastic and said it should not be attempted without supervision. Nonetheless, his work was groundbreaking in demonstrating the power of simply changing one’s diet. His brilliant work influenced many doctors and nutritionists who continued expanding the field of nutrition science. [4,5,6]

A study published in the peer-reviewed Journal of the Academy of Nutrition and Dietetics analyzed the diets of 13,000 people and compared the nutrient intake of those eating meat, to those eating meat-free diets. They found that those eating ovo-lacto vegetarian were getting higher intakes of nearly every nutrient including more fiber, more vitamin A, vitamin C, vitamin E, thiamin, riboflavin, folate, calcium, magnesium, iron, and potassium. These people were also eating less harmful items like saturated fat and cholesterol. [8,9]

The ovo-lacto vegetarians were, on average, eating 363 fewer calories every day normally. The researchers concluded that “Just following a vegetarian diet alone, without focusing on calorie reduction, could result in initial weight loss for some individuals.” [8] As for long term sustainability, more plant-based diets are the only types of diets that have been shown to be long-lived. [10] Additionally, according to a study published in the peer-reviewed journal Metabolism, found that those eating more plant-based diets appear to have an 11% higher resting metabolic rate. In fact, vegetarians may burn more calories in their sleep itself! [11]

However, it is worth noting that the vegetarians in the study of 13,000 people also consumed eggs and dairy. Although they were significantly slimmer than those eating meat, they were still, on average, overweight. “The only dietary pattern associated with, on average, ideal body weight was a strictly plant-based one.” [9]

A relatively new concept, energy density explains how one can eat more while still losing weight. “Energy density is defined as the amount of energy per unit weight of a food or beverage.” [12,13] For example, foods high in energy density include foods like crackers, cookies, butter, bacon, eggs, animal fats, and oils. Foods low in energy density include most fresh fruits and vegetables; examples include tomatoes, cucumbers, and cantaloupe. [12]

In general, there is a relationship between energy density and body weight in adults and in children and adolescents such that consuming diets lower in energy density may be an effective strategy for managing body weight. [13] This occurs because people tend to eat the same weight of food to feel full. When there are fewer calories per pound, the amount of calories consumed is reduced, thus leading to weight loss.

For example, a study published in The American Journal of Clinical Nutrition compared the effects of high and low energy density diets among obese and non-obese subjects. Subjects were allowed to eat to satiety, or until full. On average, subjects reached satiety on a diet low in energy density at about 1570 kcal versus 3000 kcal on the diet high in energy density. “The low energy density meals contained a large amount of bulk as fresh fruits, vegetables, whole grains, and dried beans with minimum fat. The high energy density meals contained minimum bulk and larger amounts of fat and simple sugars as meats and desserts.” [12,14]

Using this method of not eating less food, but eating foods that have lower energy densities, one can significantly lose weight in a healthy manner without feeling deprived or hunger. Eating plant-based also increases the density per calorie eaten of micronutrients like minerals, vitamins, antioxidants, and phytochemicals. These nutrients are both life and health promoting.

For more information about this method check out Dr. Dean Ornish’s book Eat More, Weigh Less. Also, see these articles from Forks Over Knives about How Eating More Can Help You Weigh Less and The Calorie Density Approach to Nutrition and Lifelong Weight Management. Make sure to check out this success story as well. Additionally, watch this video by nutritionist Jeff Novick. [15] Lastly, please visit NutritionFacts.org for hundreds of free videos on virtually any nutrition-based topic.