Understand obesity before treating it

The central nervous system regulates a person's weight, with many variables in play, and both internal and external factors can increase or decrease calorie intake and expenditure.


Treating obesity isn't just a matter of counting calories, according to Fatima Cody Stanford, MD, MPH, MPA, MBA, FACP.

“We've learned that weight regulation is pretty simple: It's about putting calories in … and taking calories out … and if we can just get this balanced, then we should be OK,” she said. “Unfortunately, this is indeed incorrect. And when we continue to perpetuate this to our patients … we will continue to have this continued rise in obesity within our adult population here in the United States and around the world.”

The bottom line is that there may be many different reasons why a patient struggles with weight Image by BrianAJackson
The bottom line is that there may be many different reasons why a patient struggles with weight. Image by BrianAJackson

At a talk at Internal Medicine Meeting 2021: Virtual Experience, Dr. Stanford, who is an obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School in Boston, offered an overview on the multifactorial nature of obesity, as well as an update on treatment strategies.

More than just diet

The central nervous system regulates a person's weight, with many variables in play, Dr. Stanford explained. Just because a patient eats lean proteins, whole grains, and fruits and vegetables doesn't necessarily mean they will have a lean phenotype, she said.

Physical activity alone, meanwhile, does more to help patients maintain weight than to lose it. “We are selling the wrong messaging to our patients who exercise to lose weight when, on average, it helps us to maintain our weight, regardless of how much excess we carry or how much we are closer to a healthier weight,” Dr. Stanford said.

In addition, sleep quality and duration can affect the body's weight regulation, so physicians should be aware of what medications might be interfering with a patient's sleep and should ask patients about their sleep habits, Dr. Stanford noted.

“The brain wants to be awake when it's bright outside … or when it's dark outside, we want to be asleep,” she said. “And so, when we flip the nail on its head, so for example, if you're a nocturnist, you might have noticed a weight shift and you thought, ‘Oh, maybe it's my eating.’ But maybe it was just the fact that you deviated from the natural course of humans, which is to be awake during the day and sleep at night.”

Both internal and external factors can affect a person's weight, Dr. Stanford noted.

In the former category, hyperreactivity to environmental food cues, delayed satiety, and disordered eating can increase calorie intake. Gut microbiota, in contrast, is an internal factor that can decrease energy expenditure: “The gut microbiota of those that are lean versus those that have obesity are quite different, so much so that we can often take the gut microbiota out of individuals that are lean and place it in those that have obesity and see weight shifts with no other modifications. That research is being done,” Dr. Stanford said. Other internal factors that may decrease expenditure include thermogenesis and physical disabilities, while internal factors that can both increase intake and decrease expenditure include genetic and epigenetic factors, age-related changes (e.g., menopause), and mood disturbances (e.g., depression or anxiety disorder).

Outside factors that may increase intake, meanwhile, include environmental and chemical toxins, pervasive food advertising, and large portion sizes, while those that may decrease expenditure include the built environment, sedentary time, and labor-saving devices. External factors that may increase intake and decrease expenditure include stress, weight cycling, and maternal and paternal obesity. “I really want to just put a little pin in this maternal/paternal obesity,” Dr. Stanford said. “It's important for us to note that if parents, [the] mom and dad, have obesity, we know that children have a 50% to 85% likelihood of having obesity, even when optimal behaviors are adopted.”

The bottom line is that there may be many different reasons why a patient struggles with weight, Dr. Stanford stressed. “We can't oversimplify this,” she said. “When we're thinking about our patients that are coming in telling us, ‘Hey, I'm eating well and exercising,’ we need to think about the other factors that may be contributing to them having this disease that we call obesity.”

Patients with a body mass index (BMI) between 18.5 and 24.9 kg/m2 are considered to be at normal weight, Dr. Stanford said, whereas obesity is defined in three classes: mild (BMI of 30 to 34.9 kg/m2), moderate (BMI of 35 to 39.9 kg/m2), and severe (BMI ≥40 kg/m2). But be careful with language when discussing obesity with patients, she cautioned.

“One word we want to delete or just cancel is ‘obese’ itself. That is a descriptor; it does not define the person that has obesity, and it can be seen as highly stigmatizing,” Dr. Stanford said. “Notice I said, ‘with overweight,’ ‘have overweight or obesity,’ using people-first language to be respectful of our patients that have this disease process.”

Lifestyle modification

Treatment for obesity usually takes a graduated approach, Dr. Stanford said, beginning with lifestyle modification (e.g., diet and exercise) and continuing to pharmacotherapy and metabolic or bariatric surgery. “We typically will reserve metabolic and bariatric surgery for those that have moderate to severe obesity, but there are occasionally times—let's say when someone has poorly controlled type 2 diabetes—where we might consider metabolic and bariatric surgery at a lower BMI threshold,” she said.

Current dietary recommendations to help patients lose weight focus on eating patterns that include a variety of nutrient-rich foods, limit energy-dense foods, and reduce overall energy density, Dr. Stanford explained. “Reducing the diet's energy density allows individuals to consume satisfying amounts of foods for fewer calories, and so that's a really a bargain,” she said. For example, a quarter-cup of raisins, a high-density food, has the same number of calories as four cups of cherry tomatoes, a low-density food. Strategies that lower energy density are also flexible and can be applied to multiple dietary patterns to meet patients' individual energy needs, taste preferences, and cultural backgrounds, among other factors.

Dr. Stanford outlined some nutritional goals and practical dietary strategies for weight loss or maintenance. Fat should make up 20% to 35% of daily total calorie intake. “You want to substitute some lower-fat foods for those that are higher in fat, and we want to really focus on mono- and polyunsaturated fats,” she said. Protein, which promotes satiety, should make up 10% to 35% of daily calorie intake. “We want to look at lean meats, poultry without skin, fish, egg, legumes, tofu, and low-fat dairy products,” she said.

Carbohydrates make up the greatest percentage of daily calories, 45% to 65%, Dr. Stanford said, but the type of carbohydrate matters, and patients should consume whole grains rather than refined grains. Dietary fiber is also an important macronutrient. Twenty to 35 g of fiber is recommended per day, but only about 10% of adults get that amount, Dr. Stanford said. To boost fiber intake, patients should focus on legumes, fruits, vegetables, and whole grains. Added sugar should be limited to less than 10% of daily calorie intake, she said, and for beverages, water is best.

The other main area of lifestyle modification is activity, Dr. Stanford said. Patients can get moving by increasing aerobic, muscle-strengthening, and bone-strengthening exercise. The optimal goal is at least 150 minutes of moderate-intensity aerobic activity per week, she said. “As a rule of thumb, … a person [should be] able to talk during that activity, but not sing.”

Muscle-strengthening exercises, such as lifting weights or doing pushups, increase skeletal muscle strength, power, endurance, and mass. Bone-strengthening activity, or weight-bearing activity, produces an impact or tension force in the bones and promotes bone growth and strength. This category can overlap with the other categories, since aerobic and muscle-strengthening exercises may also be bone strengthening, Dr. Stanford said.

Pharmacotherapy and surgery

Medications and surgical procedures can be helpful when lifestyle modifications are not enough on their own.

Antiobesity pharmacotherapy agents are categorized into three primary groups, Dr. Stanford said: centrally acting medications that impair dietary intake, those that act peripherally to impair dietary absorption, and those that increase energy expenditure. Those currently approved by the FDA as antiobesity drugs include central nervous system stimulants and anorexiants (phentermine, phentermine-topiramate, diethylpropion, phendimetrazine, and benzphetamine), bupropion/naltrexone, and gastrointestinal agents such as orlistat and glucagon-like peptide-1 receptor agonists.

Of these, phentermine/topiramate, bupropion/naltrexone, orlistat, and glucagon-like peptide-1 receptor agonists are FDA approved for long-term use to treat obesity, Dr. Stanford said. “It's important to note that only those agents that came on the market in 2012 and beyond have such a designation,” she said. Other antiobesity pharmacotherapy agents include topiramate, zonisamide, bupropion, metformin, pramlintide, and the sodium-glucose cotransporter-2 inhibitors canagliflozin and dapagliflozin.

Regarding surgery, the most common metabolic surgical procedure in the U.S. is vertical sleeve gastrectomy, followed by the Roux-en-Y gastric bypass, Dr. Stanford said. Patients with severe obesity and those with a BMI of 35 to 39.9 kg/m2 and one or more serious comorbid condition (such as type 2 diabetes) meet the criteria for potential surgery. Surgical candidates should also have prior unsuccessful attempts at weight loss, acceptable operative risk, and the ability to participate in treatment and long-term follow-up, Dr. Stanford said.

In addition, gastric bypass, like any treatment to address obesity, should be tailored to the individual patient, she noted. Decision making regarding surgery should take into account the patient's understanding of both the procedure and the resulting lifestyle changes that will be needed to sustain long-term weight loss. “This is not a panacea,” she said.

Dr. Stanford concluded her talk by emphasizing the complexity involved in treating obesity, noting that it is a pandemic disorder. Diet and exercise should be first-line interventions for weight loss, and although pharmacotherapy and/or metabolic/bariatric surgery should be considered for patients who meet the criteria, appropriate treatment is very uncommon.

“Right now, only 1% of patients with severe obesity get metabolic and bariatric surgery, and only 2% of patients with obesity, at all, get pharmacotherapy for the treatment of their disease,” Dr. Stanford said. “Obesity is a chronic disease, which requires lifelong treatment.”