The Brain’s Role in Obesity

As diet and behavior change experts, we offer so much to our clients with overweight and obesity. Yet, with all of our skill and all of their apparent effort, so many people appear resistant to weight loss. Why? Are we missing something? Are our clients dishonest about their eating and exercise habits?

I was fortunate to hear B. Gabriel Smolarz, MD, MS, FACE, Dipl ABOM, medical director of obesity for Novo Nordisk, speak at a partially sponsored conference. I left his talk both enlightened and more curious about my patients who just couldn’t lose weight. I reached out to Smolarz to learn more.

“The brain regulates all of our eating in three ways,” he says:

1. The homeostatic primitive pathways, between the gut-producing hormones and neurotransmitters in the brain, drive hunger and satiety.
2. Eating for pleasure, hedonic eating, is driven by reward pathways in the brain.
3. Using the brain’s advanced executive function, we consciously decide what, when, and, perhaps, how much to eat.

Metabolism Gone Awry
As RDs, we individualize our recommendations based on our clients’ needs and the reasons for their extra pounds: too much fast food or sugary drinks, not enough vegetables, super-sized portions. But what if we’re missing something essential?

“The disease of obesity causes overeating. Overeating does not cause the disease of obesity,” Smolarz says and then repeats for emphasis. He asks RDs to view what he calls “essential obesity” similar to the way we view the well-known disease of essential hypertension, in which the body sets blood pressure to harmful levels. “We counsel people to reduce sodium with this disease, but ultimately, the body is set to a higher blood pressure,” he says. Similarly, if the high blood pressure is due to renal artery stenosis, no amount of sodium restriction or lifestyle change will reverse it. With “essential obesity,” the primary problem is dysregulation of energy signals in the hypothalamus, the primitive pathway mentioned above. This part of the brain tells the person with essential obesity to “go get more energy,” even though the tank is full, he explains.

Though many hormones and neurotransmitters affect appetite and satiety, one of particular interest is glucagon-like peptide-1 (GLP-1), a hormone secreted by intestinal cells in response to food intake. GLP-1 acts on the hypothalamus in the brain to decrease hunger, increase feelings of fullness, and likely decrease food rewards (ie, hedonic eating). When these systems are awry, food-seeking behaviors increase, “so telling a person with essential obesity to eat less and move more won’t work,” Smolarz argues. Cognitive skills, such as calorie counting and portion control strategies, are no match for the primitive brain in the presence of an imbalance in the hunger and satiety centers.

Just as health care providers treat the core problems of essential hypertension, depression, and hypothyroidism, providers must treat the core problem of essential obesity: Energy dysregulation is biologically based and influenced by both our genes and environment. Smolarz encourages RDs to refer weight loss–resistant clients to a specialist in obesity medicine for assessment and medical intervention.

Working in drug research for about a decade gave me extensive experience with various weight loss medications. Many subjects in the studies benefitted greatly from both medical and lifestyle interventions. More recently, a patient with type 2 diabetes thanked me for helping to get her medications changed. Among other changes, her physician added a GLP-1 analog. My patient reported that it changed her life because she no longer thought about food all day. Imagine how much more control she felt because this new drug worked on not only the hunger and satiety centers of the brain but also the food reward system.

Obesity as a disease is a fascinating area of study. I hope you’ll join me in learning more. Dietitians will have greater ability to effect positive behavioral and health changes in our clients and followers. You can find out more at Truth About Weight and Rethink Obesity.

— Jill Weisenberger, MS, RDN, CDCES, CHWC, FAND, is a freelance writer and nutrition and diabetes consultant to the food industry, including the Norwegian Seafood Council and The Dairy Alliance. She lives in southeastern Virginia and is the author of four books and a new written course, The Beginner’s Guide to What to Eat with Type 2 Diabetes.

2 Comment

  1. Excellent post! This is critical information for all RDs, especially those working with weight management clients.

  2. Time for a paradigm shift in how we work with our clients. Compassion and care must be part of the conversation as well as comprehensive collaboration and realistic expectations. We must be advocates for our patients

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