“I know what to do; I’m just not doing it.”

Dr. Melissa Scull


Prior to starting a career in obesity medicine, my primary care patients would often say this to me when I tried to give dietary advice. I never quite knew how to respond or how to help. We were both connecting weight to willpower. Although willpower is helpful for achieving short-term goals, it is not enough to make the lifelong changes needed to treat the disease of obesity.

Think of someone you know who has a consistent, long-term, healthy habit. What keeps them going? It’s likely that what they’re doing makes them feel good, either mentally, physically, or both. It’s also likely that they don’t get a lot of negative feedback from this activity.

Psychologically, they probably don’t feel down, depressed or hopeless about their healthy habit. Physically, they don’t feel uncomfortable, ill or in pain. If there is any discomfort, it is outweighed by the benefits. When you think about it, it’s a very simple scale of more good than bad.

Now, imagine you change a habit and your body physically and psychologically feels worse. Despite some positive feedback, the bad outweighs the good. Would you continue this activity?

This is what weight loss feels like for many people, and it’s not because they have less willpower. Obesity is a disease. Or, as I like to say, “It’s chemistry, not character.”

As an obesity medicine specialist, I finally have the knowledge to help my patients understand that obesity is not a moral failure. Of course, knowing what to eat and how to exercise is important, but successful treatment is far more nuanced. Understanding the causes of obesity helps my patients feel like they can stop trying to treat the disease on their own, and it helps us, as a team, move forward with evidence-based approaches.

So what causes obesity and why is it so hard to lose weight? The science is extensive, but there are a few important points I explain to all my patients to help them understand why they struggle with weight.

First, people who struggle with weight tend to have higher hunger hormones at baseline than people who do not struggle with weight. In a healthy feedback system, hunger hormones go down as we eat (telling your brain “you’re not hungry anymore!”), while satiety hormones go up (telling your brain “you’re full!”).

People who struggle with weight may have hormones that don’t act this way. The process of losing weight also causes further increasing hunger hormones and decreasing satiety hormones. In other words, it is harder for patients who struggle with weight to feel full and even harder when they start to lose weight. They don’t choose to experience this; it’s their brain chemistry.

Furthermore, there is strong evidence that our bodies defend against weight loss no matter where our weight starts. Weight loss causes our metabolism to slow down. Some studies have shown this slowing can last up to six years after weight loss has occurred. This is likely an evolutionary adaptation to try to protect us from starving.

Unfortunately, evolution hasn’t caught up to the fact that we have more than enough (though too often unhealthy) food available. It would be great if our bodies did a better job at protecting us against weight gain than weight loss, but we have to work with what we’re given.

We are also constantly exposed to foods that hijack our brain’s reward system. Foods high in processed carbohydrates and sugars, especially, significantly raise the “happy hormone” in our brain called dopamine. When our brain experiences dopamine it thinks “this must be good for me because it feels great!” and it craves the experience again.

People who struggle with weight tend to have a lower dopamine response. They have to eat more of the high sugar/high processed carbohydrate food to get the same level of brain happiness and pleasure.

Lastly, I explain to patients that they’re not necessarily wrong to feel that they “look at food and gain weight.” Eating too much and eating too often contribute to weight gain, as does a slowing metabolism in response to weight loss. But, interestingly, it also seems the bacteria in our intestines play a role. Studies have shown that those who struggle with weight tend to have a different balance of bacteria in their colon than those who don’t.

This type of bacteria has been shown to correlate with both absorbing more calories from the food you eat, and weight gain. My patients may literally be absorbing more calories than someone of a normal weight does from the same exact food.

With every treatment recommendation I make, I explain why I think it will help with weight loss. It is much easier for people to make lifestyle change when they understand why they are doing it, and it is much easier for people to sustain lifestyle change when it doesn’t feel so physically or emotionally unpleasant.

We discuss making improvements in diet, physical activity, sleep and stress that have been shown to help decrease hunger hormones and improve metabolism. When possible, we try to stop medications that may be causing weight gain. If appropriate, we talk about medications that can help counteract all of the unhelpful hormonal and metabolic responses the body has to weight loss. For those patients who qualify and are interested, we can discuss the option of surgical treatments.

When we, as patients and providers, understand what we are up against, we can focus on lifestyle changes and treatments that target the underlying causes of weight gain.

At CMC’s New England Weight Management Institute we seek to affect hormonal and chemical signaling in a way that will stop the body from fighting so hard against weight loss. With the most up-to-date research and evidence-based treatments, we can finally give patients the explanation and understanding they deserve to take meaningful steps toward a long-term solution, hand in hand.


Thursday, May 28, 2020