The blues and the bulge

Are obesity and depression linked? If so, what kind of relationship exists and how can it be explained?  A recent study based in northern Finland investigates.

Obesity is growing with alarming prevalence. In Australia, the 1999-2000 Australian Diabetes Obesity and Lifestyle Study found that 60% of Australians over 25 years were overweight and 21% of these were obese.  Depression is also increasing and has been linked to other health conditions such as heart diseases. The relationship between obesity and depression is of growing importance and will affect prevention and treatment methods.

Very few studies examine depression and obesity over time. This study was was based in northern Finland and focussed on a group born in 1966. A longitudinal study is when a cohort or group of people are followed for a period of time to see the development of certain conditions. A total of 8 451 subjects participated in the study which used surveys at 14 (adolescents) and 31 years (young adult) to determine if depression was linked to obesity.

The study found that adolescent obesity is associated with depression during young adulthood. The study suggested that being overweight or obese at adolescence is associated with an increased chance of being simultaneously depressed during the same period of time. Therefore, it is uncertain if depression during young adulthood was due to depressive symptoms existing during adolescence or because of the obesity associated with these symptoms. 

In particular, excess fat around the stomach area may be closely linked to simultaneous depression in males. Abdominal obesity and body mass index (BMI) were both used to measure obesity in the study group. Abdominal obesity was measured using a waist to hip ratio (WHR) estimate. Interestingly, another study found underweight men also have an increased risk of depression. It was proposed that this may be due to males desiring more stocky builds. The feeling of inadequacy felt by males who did not necessarily conform to this ideal would predispose them to depression later on life. Similarly, larger bodies are not idealised, especially amongst females, causing feelings of inadequacy leading to a higher risk of depression. It has been suggested that the risk of depression and body weight are related through a U-shaped curve. Being underweight or overweight predisposes an individual to depression.  Obesity or even being overweight may predispose females to depression at either adolescence and during adulthood.

Dr George Blair-West, an Australian psychiatrist specialising in the therapy of morbid obesity, is an international authority on the psychology of weight loss. He is the author of Weight Loss for Food Lovers: Understanding our minds and why we sabotage our weight loss, a book that explores how and why our love of food leads us to sabotage our weight loss plans.

"Research like this is important because it reminds us that we have to stop thinking of obesity as simply a physical condition resulting from a self-discipline deficiency. Obesity is a complex condition that makes losing weight a minefield when people do not understand their deep emotional attachment to food," Dr Blair-West said.

However, both obesity and depression are highly complex conditions with a variety of other factors such as genetic makeup or marital status influencing whether or not a person is obese or depressed. The study proposed several different hypotheses for the association between obesity and depression.  Firstly, obesity could cause depression.  Obese people may have a greater risk of depression due to discrimination and prejudice against them.  Furthermore, diets low in folic acid, commonly derived from fruits and vegetables, may increase the risk of depression. Similarly, physical inactivity can cause obesity. Individuals who exercise increase the release of endorphins (happy chemicals) in the brain, resulting in increased psychological wellbeing thus physical inactivity, depression and obesity may be linked.

Alternatively, depression could cause obesity.  Depression can also result in increased comfort eating leading to obesity due to the excessive consumption of food. Furthermore, tricyclic fantidepressants can result in marked weight gain further linking obesity with depression. Other hypotheses based on biochemcial problems have also been proposed. In particular leptin, a hormone regulating mood and deriving from fatty tissue, could be involved. This is due to a degree of leptin resistance in obese people so they have an inability to respond to changes in the hormone and so are not able to easily control their moods. There were many possible explanations for the link between obesity and depression but none were conclusive.

Dr Blair-West said, "The key issue highlighted by this research is that irrespective of which comes first we need to manage a person’s depression before we ask them to try to lose weight. To ask a depressed person to face the demands of losing weight, which is complicated at the best of times, is to add insult to injury. People battling their weight have to become more comfortable with the idea of looking more deeply into the psychological issues that might sit behind their weight problem."

This study was particularly important as it examined the relationship between obesity and depression over time.  It introduced a large group of individuals looking at both females and males.  It furthered the belief that obesity and depression are linked over time and especially focussed on young people. Treatment or preventative methods encompassing both conditions may improve the efficacy of such programs.

Treatment and prevention strategies for obesity and depression could be improved if the exact relationship between them is found. Drugs could be used to treat depression and obesity at the same time, and interventions could look at targeting both obesity and depression.  For example, nutrition programs could also stress the importance of being mentally healthy.

The most effective weight loss programs generally include  behavioural therapies.  These programs encourage changes in behaviour to help an individual maintain long term weight loss. For example, meal replacement programs such as the Tony Ferguson meal replacement program that include referrals to health professionals (e.g. dietitians and psychologists) will be more effective than other programs based solely on diet. For the morbidly obese, the benefits of surgery (e.g. gastric banding) may be aided by regular psychological assessment and therapy.  Pharmacological treatment with Xenical or Reductil should also include regular support and counselling to ensure weight loss is maintained.

For more information on Dr Blair-West’s work, visit http://www.weightlossforfoodlovers.com/