One does not need to go far to find harrowing statistics about obesity.
According to National Health and Nutrition Examination Survey data, obesity in adults more than doubled over half a century — from 13.4 percent in 1962 to 38.2 percent in 2014 — and the National Bureau of Economic Research reports the estimated annual health care costs of obesity-related illness to be nearly 21 percent of annual medical spending in the United States.
With links between higher body mass index and increased risk for disease, including Type 2 diabetes, cardiovascular disease and certain cancers, public health messaging to the masses and patient advice from medical practitioners have centered on weight loss as both prevention and treatment for many chronic diseases. However, there isn’t a single therapy (dietary, surgical, pharmaceutical or otherwise) that has been shown to sustain long-term weight-loss maintenance in a significant number of people.
Researchers are only just beginning to understand the myriad factors that affect body weight and body fat, including genetics, hormones, medications, diseases, age, sleep, stress, environmental pollutants, sex, ethnicity, socioeconomic status, dietary quality and physical activity. And some epidemiological studies actually support conflicting theories on body weight and health.
For example, the “Obesity Paradox” refers to the anomaly of some people with BMIs in the overweight and obese categories, especially older adults and even with chronic disease, outliving people with normal BMIs.
“In general, there is a strong relationship between BMI and health outcomes,” says Hollie Raynor, PhD, RD, LDN, obesity researcher and co-author of the Academy’s 2016 position paper on interventions for the treatment of overweight and obesity in adults, “but there are individual differences.” Among limitations inherent to epidemiological research, according to Raynor, is that studies correlating body weight and morbidity and mortality may not control for moderating factors affecting disease risk, such as high intake of calorie-rich, low nutrient-dense foods, low intakes of nutrient-dense foods, physical inactivity and smoking.
Other concepts — including “metabolically healthy obesity” (individuals with BMIs of 30 or higher who have normal blood lipids, blood sugar and insulin levels) and “metabolically obese normal weight” (people with normal BMIs and negative health outcomes) — are countered by a much higher proportion of people with obese BMIs who are not metabolically healthy.
However, it is well recognized in behavioral health research that weight stigma (stereotyping and bias based on one’s size) is associated with increased calorie consumption and binge eating, negative body image, depression, greater likelihood of becoming obese, and reduced desire to engage in healthy behaviors.
Other studies suggest that a focus on weight in health care settings may increase false positives and negatives. For instance, if physicians look for certain diseases in patients with overweight or obese BMIs but not in individuals with normal BMIs, some conditions may be overdiagnosed in larger people or underdiagnosed in smaller people.
According to a 2014 review of unintended harm associated with public health interventions, weight loss messaging is not only ineffective, but actually can promote body dissatisfaction and disordered eating. Campaigns centered on healthy behaviors without mention of weight are better received and are more likely to result in healthy behaviors among targets, wrote the authors.
Enter the “weight-neutral” movement: a therapeutic approach to improving the health of individuals by focusing less on BMI, and more on lifestyle behaviors.
“In light of having no validated methods to help more than a small number of people lose weight and keep it off,” says Marci Evans, RD, CEDRD, CPT, who specializes in body image issues and emotional eating, “we need to use tools that will enhance clients’ health at their current weight without causing more harm — remembering to consider long-term harm as well.”