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.”
Some evidence suggests dietary restriction and a history of weight loss are associated with eating disorders. In addition, a key concern cited by weight-neutral proponents is that dietary restriction often leads to weight cycling — repeated gain and loss of weight — rather than sustained weight loss. Some research associates weight cycling with loss of lean body mass, reduced metabolic energy expenditure, increased inflammation, hypertension, insulin resistance, dyslipidemia, osteoporotic fracture, some types of cancer, cardiovascular risk, mortality risk and emotional distress. Other studies suggest weight cycling is more strongly linked with certain adverse health outcomes than is having an obese BMI.
But many obesity researchers do not agree with these conclusions, citing studies that show losing even 3 percent to 5 percent of body weight reduces some health risks in people with elevated BMIs.
“Lifestyle interventions that include dietary, physical activity and behavior components typically do not lead to eating disorders,” says Raynor, adding that structured eating can even help with bulimia nervosa and binge-eating disorder — although robust, multidisciplinary intervention programs designed by researchers may not be accessible for many people or covered by insurance.
On the other hand, there is limited research on the efficacy of weight-neutral interventions; although some studies have found significantly better physiological, behavioral and psychological outcomes compared to weight-centric models and dieting, including low dropout rates and no adverse events, those study samples were small and did not include individuals classified as morbidly obese. Other criticisms include that a weight-neutral approach gives people a “free pass” to engage in unhealthy lifestyle behaviors — and that weight loss should be pursued as soon as possible for people with obese BMIs.
But weight neutrality is not in conflict with, and actually helps support, the Nutrition Care Process, according to Jennifer McGurk, RDN, CDN, CDE, CEDRD, who advocates for the inclusion of weight-neutral concepts in continuing professional education for registered dietitian nutritionists.
“Many weight management trainings do not address binge-eating disorder,” says McGurk of a behavior that is prevalent in up to 30 percent of people seeking weight loss treatment. “Behavioral health is a critical component of health care, yet many weight management approaches address food and diet only — without taking into consideration individuals’ genetic predispositions, preferences and feelings surrounding food.”
Evans agrees, adding that while dietetics is grounded in compassion and individualized care, there is tremendous pressure as practitioners to focus on weight loss. “As registered dietitian nutritionists, we need to self-assess,” says Evans, “And determine whether an intervention will truly improve a client’s health, or if it comes from a desire to make them smaller.”