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Why the Number on the Scale Means Less Than You Think

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For some, it’s a part of their morning ritual. People will brew some coffee, brush their teeth, and step on the scale to see if the number from the day before has somehow skyrocketed to a personally uncomfortable level. But weight, a thing that is stressed in advertisements, storylines on TV, and often in our own heads is likely much too…weighted. The same goes for body mass index (BMI), a metric calculated based on weight and height.

Last month, the Canadian Medical Association Journal published new clinical practice guidelines surrounding bodyweight and health. While officially calling obesity as a chronic illness, the report also said that obesity should not be measured by body weight BMI alone. Instead, the term “obese” should only be used in instances where someone has a related medical condition. Currently, obesity is defined by the U.S. Centers for Disease Control and Prevention (CDC) as having a BMI of 30 or higher. But the report authors now advocate for assessing other health conditions, medical history, family history, and mental health when caring for patients who may fall into the “overweight” or “obese” categories. Clinicians should also be respectful of people’s relationship with their weight and be respectful when discussing it in order to value the patient and decrease stigma, the guidelines say.

“The health care community worldwide has been moving toward this way of thinking, and it’s exactly the right direction,” said Anastassia Amaro, MD, the medical director of Penn Metabolic Medicine and an associate professor of Clinical Medicine in the Perelman School of Medicine at the University of Pennsylvania. “BMI can be a useful tool for screening patients, and it’s a helpful metric to use when we are doing research or analyzing large populations of people. But when counseling patients and creating individualized interventions to address their health concerns, weight and BMI are not the primary focus at Penn.”

What BMI Doesn’t Say

Most people know that excessive weight and higher BMI is tied to cardiovascular disease, diabetes, orthopaedic issues, and even certain cancers. But the relationship is not exactly straightforward.

“Biologically, the health problems associated with weight come from excess fat tissue, which can subsequently cause inflammation and hormonal changes, and neither weight nor BMI even take into account what pounds come from fat and what come from muscle,” Amaro said. “In addition, unhealthy weight can be the cause of certain conditions wherein others it’s a consequence.”

Where fat is located on the body also affects its impact on health, notes Octavia Pickett-Blakely, MD, MHS, the director of the GI Nutrition, Obesity and Celiac Disease Program and an assistant professor of Clinical Medicine at Penn. “ ‘Belly fat,’ for instance, raises the risk of diabetes and cardiovascular diseases for women and men more than truncal fat which is concentrated in the lower body (hips). A number on the scale or a BMI chart doesn’t even come close to making that distinction,” she said.

What’s more, genetics and family history play a big role in both health and weight. Whether a person is predisposed to have a higher or lower weight is a separate question from whether they are at an elevated risk of health problems due to genetics or behavior.

“Body weight can be extremely misleading,” Blakely said. “It’s easy to assume that the individual with a healthy BMI doesn’t have any of the comorbidities that the individual with a higher BMI has. But the ‘thin’ patient may have poor cardiovascular health from a lack of physical activity, or they may have diabetes or prediabetes from a diet heavy in fast food.”

Because of these complexities, setting health-oriented goals for weight loss can’t be one-size-fits-all.

“One person in the obese category can lose five pounds and see lower blood pressure and other positive impacts on their health metrics, while their peer, because of their unique health and genetic makeup, may lose five pounds and not see any effect on their health,” Amaro explained. “Clinicians can help patients form goals that can actually make the person healthier and that are based around every individual and their biologic makeup.”

The Shift in Thinking: A physician’s role in weight management

In decades past, patients who had or were at risk for weight-related health conditions were commonly directed by their primary care doctor to lose a certain number of pounds and then come back for follow-up and treatment, depending on their health needs. That still happens today, but as Pickett-Blakely and Amaro suggest, that may not be the best course.

“In the past, such an approach could have been justified by our insufficient understanding of the obesity biology and lack of therapeutic options,” Amaro said. “In recent decades, obesity medicine and bariatric surgery have been developing rapidly, and physician can now offer various tools and treatments to persons with obesity. Putting pressure or even blame on a patient instead of offering a treatment attempt can discourage the patients from seeing a doctor at all.”

Most patients who come to Pickett-Blakely’s clinic for weight-management care have a goal weight in mind they’d like to hit. “Often, their goal is to reach a weight they were at a time in their life when they were really happy,” Pickett-Blakely said. “I recommend those interested in losing weight try to understand where their ‘goal’ originates, so that we can then focus on creating goals based on managing conditions like high blood pressure and diabetes, conditions that affect their life — rather than trying to “get back to” some number on the scale.”

Instead of specifying a number of pounds to lose, primary care doctors and metabolic medicine specialists can support their patients by treating weight-related health conditions with prescribed activity, diet, the use of medication, or surgery. Counseling is also a vital component.

“As the guidelines suggest, we should treat the whole patient,” Amaro said. “Medicine, especially this kind of medicine, is multifactorial. Clinicians should seek to understand their patients’ physical, mental and emotional health, their stressors, their diets, and their physical habits. After we understand, we can help them strategize on how to be healthier. A patient’s overall physical and mental health are what really matters.”

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