On the surface eating disorders and obesity seem to be conditions that are polar opposites. A person with anorexia can die from lack of nutrition while a morbidly obese person can die from over-nutrition. The treatments for both conditions also seem to opposite from each other. Those with eating disorders like anorexia nervosa are encouraged to eat more, while patients with obesity are encouraged to limit their food intake. Eating disorders and obesity certainly don’t seem to have much in common.
Affective Spectrum Disorder.
When you dig a little deeper, some interesting commonalities do start to emerge. Over a decade ago James Hudson and Harrison Pope, two Psychiatrists from Harvard, first proposed that eating disorders were part of a condition they termed Affective Spectrum Disorder (ASD). They showed that certain brain disorders like depression, ADHD, obsessive compulsive disorder, eating disorders, anxiety disorders and fibromyalgia seem to share an hereditary link and they respond in a similar fashion to the same medications:
Because they never identified the triggers or underlying pathology of ASD or tie it to metabolic problems, their disease model never made it out of academic medicine. Since then certain types of eating disorders such as binge eating disorder (BED) and bulimia nervosa (BN) have been clearly tied to obesity. To date anorexia nervosa has not been tied to obesity, but in my opinion this connection has been missed because everyone is focusing on weight or size (BMI) rather than fat storage and brain function.
Obesity—Too Much Fat Relative to Other Stuff in Your Body.
Obesity is defined as excessive body fat, so the most accurate way to access obesity is to measure body composition. For the past few decades I have measured the body composition of all my patients and I have noticed some interesting trends. Many normal size or even thin people seem to have excessive body fat and those with excessive body fat also seem to have many of the brain dysfunction symptoms that would qualify them for one or more of the conditions under the Affective Spectrum Disorder umbrella. This is also true for many people with anorexia. They seem to want to hold onto some extra fat even as they lose a lot of lean body mass from under-eating. Patients with advanced anorexia have clearly depleted most of their fat stores. What I find interesting is that when anorexics are re-fed and gain weight, they tend to store a lot of abdominal or visceral fat without adding much fat to their extremities. They store a lot more central fat than a normal person eating the same amount of food.
This is true even when they are still significantly underweight. In essence they become a thin obese person when they start to eat more food.
Central obesity is also associated with metabolic problems like insulin resistance and heart disease. Binge eating disorder and bulimia nervosa have been much more closely tied to obesity than anorexia. Regardless of how much or little fat they store, all of these disorders seem to be associated with a tendency to store excessive fat, especially in the abdominal region. Although the physiology of fat storage is complex, the brain plays a key role in fat storage through the hypothalamic pituitary endocrine axis. The brain controls many of the hormones that promote fat storage. For some reason people with eating disorders seem to have brains that want to store more fat.
The Connection Between Obesity, Eating Disorders and Other Common Brain Disorders.
People with eating disorders also tend to have a lot of other brain disorders like depression, anxiety, ADHD, PTSD, OCD, fibromyalgia and similar conditions. Thus it appears that Hudson and Pope were on to something with their Affective Spectrum Disorder. A more recent paper by Hudson and Pope documents the co-morbidities of eating disorders:
It is also well established that obesity is co-morbid with many other common brain disorders:
I don’t know about you, but I think there are some dots here that need to be connected. Eating disorders are associated with obesity and other brain disorders. Obesity is associated with common brain disorders. Many common brain disorders seem to be associated with obesity and eating disorders. As Hudson and Pope suggested, this type of overlap phenomena suggests that there might be a common pathological process driving at least some of these disorders.
Transition to a New Disease Model: CARB Syndrome.
Over the years I have developed the Carbohydrate Associated Reversible Brain syndrome or CARB syndrome disease model to connect these dots. This model is based on the premise that consuming certain dietary elements can over time lead to a form of food induced brain dysfunction where the brain doesn’t work as intended. Although the process of how this comes about is likely quite complex, we do have a few hints. Excessive fructose mainly from sugar and HFCS and high glycemic carbohydrates mainly from grains seem to act in concert to adversely affect brain function.
Some like Gary Taubes argue that these dietary elements lead to insulin resistance and high levels of insulin promote fat storage in fat cells. When it comes to fat storage, he believes that we can leave the brain out of the equation. I agree with him that these dietary elements tend to promote fat storage on a cellular level, but I also suspect that these dietary elements directly adversely affect the brain. Because the brain plays a key role in auto-regulating fat stores, people with CARB syndrome tend to store extra fat at virtually any caloric intake. People with CARB syndrome also seem to have low levels of monoamine neurotransmitters like dopamine, norepinephrine and serotonin, resulting in up to 22 brain dysfunction symptoms that are typical of the disease. These symptoms overlap with the symptoms of many common classic brain disorders like depression, so over time they often are diagnosed with multiple conditions.
Thus I believe that these dietary elements both promote fat storage on a cellular level and lead to brain dysfunction. The brain dysfunction then promotes even more fat storage. In other words you end up with a double whammy to your health—dangerous insulin resistance and too much body fat and a brain that doesn’t work as intended.
A New Disease Has Crept on the Scene.
Is CARB syndrome really a new disease that is distinct from classical disorders? In my opinion it clearly is. Years ago all depressed patients lost their appetite and lost weight. In recent years many depressed patients have an increased appetite, cravings for sweet and starchy foods and weight gain. In my opinion this is CARB syndrome, not true hereditary major depression. If you hope to successfully treat a disease, it’s important to understand the underlying pathological process driving the disease. When you treat CARB syndrome depression with standard treatments for classic depression—mainly high dose SSRI medications, patients tend to get worse over time rather than better.
Carbohydrate Cravings Are Driving the Bus.
To see how eating disorders are tied into CARB syndrome, an example might be helpful. Recently I admitted a young woman into the hospital with severe anorexia. Her blood electrolytes were abnormal to the point where it could adversely affect her heart. In the past she has also been diagnosed with severe anxiety and depression. She has the binge-purge type of anorexia and she is extremely under-weight. The most prominent symptom of CARB syndrome is strong cravings for sweet and starchy foods. When I asked her about this symptom, she denied having such cravings. That’s because when someone with anorexia restricts their food intake to a severe degree, they end up in ketosis which tends to suppress both hunger and carbohydrate cravings. That’s one reason why they can easily avoid eating—they simply have no hunger or cravings. They can only achieve this state by severely limiting food intake. Without huger or cravings, their life settles down somewhat, even though they still have other typical brain dysfunction symptoms.
When I asked her about her past, she admitted that she used to have very strong cravings for sweet and starchy foods and she also used to binge on this type of food. That’s one reason people with anorexia don’t eat. Once they start to eat, the cravings return and when they eat this type of food, they quickly feel worse and start storing more visceral fat even when they are thin. They somehow sense that they are storing too much fat even when everyone else thinks “It’s all in their head”.
Although all patients with CARB syndrome regardless of their size or weight tend to have brain dysfunction symptoms, these symptoms are often worse in people who are thinner. That’s because when they restrict their eating, they consume very little of the amino acids that are necessary to make dopamine, norepinephrine and serotonin. Because they already have low levels of these neurotransmitters, starving the brain seems to make these symptoms worse.
Effective Treatment: Focus on the Brain.
If eating disorders and obesity are connected, then the treatment approach for both conditions should be similar. The only difference between these two groups when it comes to body size is the amount of food they are eating, but both groups are in the same type of fat-storage mode. The key to successful treatment is to slowly move them out of this mode and the best way to do so is to focus on improving their brain function. The most effective way to improve their brain function is to remove the triggers of CARB syndrome from the diet—excessive fructose and high glycemic carbohydrates. Although someone with anorexia obviously needs to increase their food intake and someone with morbid obesity needs to eat less, I place most of my focus on the type of food they are eating. If they eat the right type of food, their body composition will tend to drift back towards normal. If you give someone with anorexia the wrong type of food, their brain function will get worse, not better and they will strongly appose this by once again reducing food intake.
For both groups I recommend following a low carbohydrate, moderate protein, high fat diet. The fats should be healthy fats like coconut oil, olive oil, omega 3 fatty acids and animal fats, especially from grass fed animals. I also recommend taking certain supplements to improve brain function and I discuss these supplements in detail on other posts on this site. Exercise is helpful mainly because it is a good way to improve brain function.
I believe that Hudson and Pope were right—many common brain disorders are driven by a shared pathology. They just didn’t take their concept far enough. The CARB syndrome disease model completes the connection between common brain disorders, eating disorders and obesity. Treating eating disorders is still very challenging, but this new disease model gives us more effective tools to use. Hopefully future research will help us to better define the connections between these common disorders. In the mean time let’s use the effective tools derived from the CARB syndrome model to help these desperately ill patients.