Depression’s Collateral Damage: The Obesity Link

We are products of our genetics, our past, and our current decisions. More and more data is linking adverse past experiences to long-term mental health issues as well as obesity. In fact, one of the most significant  non-genetic risk factors associated with anxiety and depression includes earlier life adversity, such as trauma or neglect, and it seems that underlying trauma also contributes to weight gain. 

What you’ll find in this article:

The connection between trauma and obesity | The connection between obesity and depression | Depression can lead to obesity and obesity can lead to depression | Your brain neurochemistry affects your mood and eating behavior | How to win the battle

The connection between trauma and obesity

For many of those affected, trauma was experienced back in childhood and not effectively ever coped with. There is plenty of evidence that post-traumatic stress disorder (PTSD), a common psychiatric and anxiety disorder caused by traumatic events, might be attributed to the disorder of the Hypothalamic-Pituitary-Adrenal axis (HPA axis). The result of this stimulated axis is the body’s chronic release of cortisol, a hormone involved in the fight or flight response. Cortisol, it seems, is the common denominator between PTSD, Depression, and Obesity.  In fact, childhood adversity, including maltreatment (i.e., abuse and neglect) and other traumatic events, has been compellingly associated with a life-long increased risk for psychopathology and chronic health problems.

Not just war veterans suffer from PTSD. More girls than boys suffer sexual abuse as children, predisposing women to more severe reactions to traumas later in life. Women are also biologically more prone to PTSD than men. Researchers also found that sexual trauma causes more emotional suffering and is more likely to contribute to a PTSD than other types of trauma.  

People with PTSD, anxiety, and depression tend to have reduced amounts of serotonin in their brain and elevated levels of cortisol in their bloodstream. In the short run, cortisol release has many benefits. It prepares one for physical and emotional challenges, generates bursts of energy in the face of trauma, and triggers surges of immune activity when confronted with infectious diseases. However, cortisol production becomes problematic when exposed to prolonged stress- as occurs during repeated adverse events. This results in the continuous production of cortisol. This rise in cortisol leads to reduced activity of serotonin in the brain further compounding the symptoms of depression. Additionally, elevated cortisol causes people to crave fats, sugar, and salt. This is the shared neurochemistry linking mood disorders and binge eating. The result? Obesity.  

The connection between obesity and depression

Depression can manifest in many forms. It can reduce one’s drive and energy, can lead to social isolation or can lead to risk-taking behavior. It can also have a variable effect on appetite. In some cases, depression significantly suppresses hunger. For others, persistent sadness can induce overeating and binge eating. One study  found that a specific group of US Iraq and Afghanistan Veterans who expressed signs of depression and  PTSD  also showed a tendency to binge eat. The researchers concluded that the psychiatric conditions of this group led them to become overweight or obese. This is also in agreement with published research that has revealed that a large percentage of people who binge eat have a  mood disorder, or have a history of one.  It isn’t hard to understand that how you feel can affect what kind of dietary choices you make. “Emotional eating” is, of course, the prime example of this: going for the tub of ice cream, or going for the chocolate, etc. has long been the stereotypical dietary behavior of those feeling low.    

But it’s not just a stereotype. Overeating and binge eating behaviors are typically associated with ingestion of low nutrition, high-fat/high-sugar foods. And while the sugar rush that results may produce a temporary high, there are long-term consequences.  Research suggests that regular consumption of fatty, sugary foods—especially anything deep-fried or candy-coated—tends to negatively impact overall mood and mental health. While it is true that those who are currently depressed may seek out sugary foods as a comfort, there is definitely a link between ingestion of sugar-rich foods over time and the further development of depressive symptoms. This was documented by a study from the University College London Institute of Epidemiology and Public Health in the United Kingdom. These scientists showed that sugar consumption can develop into depression, rather than being a consequence of it. These findings are not just limited to the United Kingdom. A 2002 study looked at overall sugar consumption per capita in six different countries. The lead author, which was from my medical school alma mater (The University of Texas Southwestern medical school) implicated sugar as a factor in higher rates of major depression. The relationship between mood and food intake is very complex and seems to be bi-directional. That is, mood disorders can influence food choices and food choices can influence mood disorders. 

Depression can lead to obesity and obesity can lead to depression

The connection between depression and obesity is very complex and has been the subject of clinical research for years. Hundreds of studies have been conducted to examine the relationship between depression and obesity, with conflicting theories as to which comes first. In 2008, researchers published longitudinal data which was meta-analyzed to see if depression accounts for later obesity. Their results, combining data from over 33,000 subjects, showed that depressed compared with nondepressed people are indeed significantly more likely to be obese at follow-up measurement. However, one important limitation to this finding is that all but one study included in these authors’ meta-analysis controlled for antidepressant medication use. Previously published research has identified tricyclic antidepressant medications (e.g., amitriptyline) as particularly likely to lead to weight gain over time. However, more recent data has cast doubt on the ability of antidepressants to affect one’s weight independent of other variables.  

The link between depression and obesity probably goes in both directions: depression may lead to obesity and obesity itself may lead to depression. The relationship between the two is difficult to tease apart as they share similar neurochemical processes in the brain and co-exist frequently. There are a variety of reasons as to why people tend to overeat. Most experts agree that overeating stems from a combination of factors, such as emotions, genetics, society, culture, mental health issues, and imbalanced brain neurochemistry.

Your brain neurochemistry affects your mood and eating behavior

Serotonin 

Research from human trials and animal studies have shown that foods directly influence brain neurotransmitter systems which in turn has effects on mood. Neurochemical studies have suggested a shared/common pathway for mood disorders and food cravings. Depression, for example, results from an imbalance of serotonin. When someone is craving carbs, they are being drawn to foods that encourage serotonin production.  In a sense, reaching for sugary, carbohydrate-rich foods can be a way of self-medicating depression. Although some lines of evidence do suggest this shared etiology (e.g., serotonergic dysfunction), the manner and extent to which shared biological factors are at play is not clear. Others have pointed to another potential Neurochemical, tryptophan.  Several studies have proposed that low levels of tryptophan may be the factor increasing hunger and driving food cravings, as well as contributing  to symptoms of depression. A study did find that in healthy participants, higher doses of dietary tryptophan resulted in significantly less depression and irritability and decreased anxiety. 

 Dopamine 

 Another potential link between mood disorders and eating behavior may be Dopamine. Dopamine has long been referred to as our reward-seeking hormone. Indeed, in the brain it is strongly associated with pleasurable feelings and reward- seeking behavior. Dopamine in the brain also is responsible for our feelings of satiety. Although dopamine alone may not directly cause depression, having low levels of dopamine in the brain may cause specific symptoms associated with depression. These symptoms can include: lack of motivation, difficulty concentrating, and reduction in drive. Dysfunction of dopamine is directly related to anhedonia (diminished interest or pleasure in response to stimuli that were previously perceived as rewarding) experienced in those with depression. Put in simple terms, low brain dopamine results in symptoms of depression. Here lies the food connection. Certain foods, such as those rich in sugars and fat, can temporarily release more dopamine in the brain. This dopamine connection is a bit complex. Studies find greater brain activity in areas of reward and motivation when exposed to food cues, which translates into a strong desire for food.  However, there is less dopamine rush from actual eating. This may also lead to food addictive style behaviors.  

How to Win the Battle 

We have always been told “you are what you eat”. Well, now SCIENCE says it’s true. So much data has come about regarding the inflammatory nature of our diet and cognition and mood that it is important to discuss. Finding the exact relationship between these conditions is less important than simply realizing that they exist and treating the patient holistically for better overall outcomes. Here are a few things that might help:

Avoid processed foods

Eating a healthy, balanced diet and avoiding inflammation-producing foods not only  helps fight obesity but may be protective against depression. 

Eat depression-fighting foods

Another study outlined an Antidepressant Food Scale, listing nutrients which may aid in the prevention and treatment of depression. Some of the foods mentioned fit in a low-carb diet, which in itself has been shown to help with weight loss. These included oysters, salmon, mussels, spinach, romaine lettuce, and strawberries. 

Practice intermittent fasting

Intermittent fasting has skyrocketed in popularity in recent times. Periods of deliberate fasting are practiced worldwide, mostly based on a traditional, cultural, or religious background. Known by many for its potential weight loss effects, science now shows that the practice may also be good for our mental health. Published data has shown that fasting can result in reduced anxiety and depression levels. Other studies have shown that intermittent fasting may also result in an increased level of vigilance and overall mood improvement. These beneficial effects are supported by experimental research; fasting has been  associated with beneficial neurochemical changes, including increased brain availability of serotonin, endogenous opioids, and endocannabinoids- all key players for mental wellbeing. Nonetheless, further study is required for better understanding of the links between the different effects of calorie restriction on mood.

Intermittent fasting can take different forms, from fasting one or two days a week to fasting 12 to 18 hours a day. Data are not sufficient to recommend one fasting intervention more than the others.

While there are a variety of intermittent fasting techniques, choose one that fits your lifestyle and overall goals. Lastly, this information is not to deny the true benefits of medication and/or cognitive behavioral therapy for depression/anxiety when they are indicated. However, knowing that intermittent fasting may also be a valuable complement, or alternative,  to traditional treatment plans is very encouraging and scientifically sound. 

Seek help

It is true: not every person suffering with a mood disorder is overweight or obese, and not every person who is overweight or obese has an underlying mood disorder. Nonetheless, there is a significant bi-directional relationship linking the two. The only way to effectively treat these conditions is to realize that attention to one area alone (for example, obesity) without addressing underlying traumas is only treating half the problem. Cognitive behavioral therapy, lifestyle modifications, and when necessary, pharmacotherapy, are all necessary to successfully draw you out of a mood disorder and an unhealthy lifestyle.