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.

A recent study published in the International Journal of Obesity¹ investigates whether obesity and depression are linked. 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.² Depression is also increasing and has been linked to other health conditions such as cardiovascular diseases.¹ The relationship between obesity and depression is of growing importance and has implications for treatment options and preventative measures.

Dr George Blair-West, an Australian psychiatrist specialising in the psychotherapy of morbid obesity, is an international authority on the psychology of weight loss. He is an expert in Restraint Theory and its clinical ramifications that require a very different, much more psychologically sophisticated approach to managing weight. In his workshops for doctors, psychologists and dietitians, his focus is on the complicated clinical conundrum of the psychological comorbidity that accompanies morbid obesity and the need to respect the deep emotional attachment people have to certain foods.

"Certainly in morbid obesity, psychological comorbidity is the norm," he said. "It is the classic chicken and egg story; does the weight problem cause the depression (or anxiety) or vice versa? To complicate things further we need to remember that in naturalistic studies the lifetime prevalence of major depression is over 17% in the greater population, marry this with two-thirds of the population being overweight or obese and we have a very simple basis for the comorbidity!"

Very few studies examine depression and obesity over time.¹ This study was part of a longitudinal cohort born in 1966 based in north Finland.¹ There were a total of 8,451 participants in the study which used surveys at 14 (adolescents) and 31 years (young adult) to determine if depression was linked to obesity.¹

The study found that adolescent obesity is associated with depression during young adulthood.¹ Being overweight or obese at adolescence was associated with a simultaneous increased chance of being depressed during this same period of time.¹ Therefore, it was questionable whether depression during young adulthood was primarily because depressive symptoms existed during adolescence or because of the obesity associated with these symptoms.¹

In particular, abdominal obesity may be closely linked to depression occurring simultaneously amongst males.¹ Abdominal obesity and body mass index (BMI) were both used to assess obesity in the cohort.¹ Abdominal obesity was measured using a waist to hip ratio (WHR) estimate.¹ Interestingly, another study found underweight men also have an increased risk of depression.⁴ It was hypothesised that this may be due to an idealisation of male bodies as being of stocky build as opposed to being underweight.^1,4 The feeling of inadequacy felt by males who did not necessarily conform to this ideal would predispose them to depression later on in life.^1,4 Similarly, larger bodies are not favoured by society, especially amongst females, causing similar feelings of inadequacy and resulting in an increased risk of depression.¹ It has been suggested that depression and body weight are related through a parabolic curve.⁵ Being underweight or overweight predisposes an individual to depression.⁵ Obesity or even being overweight may predispose females to depression at either adolescence and during adulthood.¹

Dr Blair-West said, "Clinically, from the treatment end, the issues are clearer – the depression must be addressed first. Very few people who are clinically depressed are able to withstand the rigours of losing weight. Weight loss, particularly with traditional, low calorie diets is something that around 80% of the population are not able to adhere to, to achieve long term weight loss. Indeed, to ask someone who is clinically depressed to embark on a weight loss plan is to add insult to injury."

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.¹ The study proposed several different hypotheses to explain the association between obesity and depression. Diets insufficient in folic acid, commonly derived from fruits and vegetables, may predispose an individual to depression.¹ Similarly, physical inactivity can cause obesity.¹ Individuals who exercise increase the release of endorphins resulting in increased psychological wellbeing thus physical inactivity, depression and obesity can be linked.¹ Depression can also result in increased comfort eating leading to obesity due to the excessive consumption of food.¹ Furthermore, tricyclic antidepressants can result in marked weight gain further linking obesity with depression.¹ Other hypotheses involving biochemical dysfunction have also been proposed.¹ In particular leptin, a hormone regulating mood and deriving from adipocytes, could predispose a person with obesity to depression.⁶ This is proposed to be due to a degree of leptin resistance in obese people so they have an inability to respond to changes in the hormone.⁶ There were many possible explanations for the link between obesity and depression but none were conclusive.

This study was particularly important as it examined the nature of the temporal relationship between obesity and depression. It introduced a large cohort of individuals and examined both females and males. It furthered the belief that obesity and depression are linked over time and in particular looked at depression amongst young people as a risk factor.¹ Treatment or preventative methods encompassing both conditions may improve the efficacy of such programs.

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.⁷ Pharmacological treatment with Xenical or Reductil should also include regular support and counselling to ensure weight loss is maintained.⁷

Dr Blair-West said, "What this issue of comorbidity highlights is two key points. First, we have to shift our thinking about obesity away from seeing it as a physical condition resulting from a self-discipline deficiency – it is a complex psychophysiological condition. Second, we need to approach it from a multidisciplinary perspective. The minimum team is a GP, Psychologist and Dietitian."

Unfortunately very few psychologists are trained in Restraint Theory, the interplay with depression and the ways in which people sabotage their weight loss. Dr Blair-West’s book Weight Loss for Food Lovers: Understanding our minds and why we sabotage our weight loss was written as a therapy manual to be used in conjunction with clinical support, for people suffering from psychologically comorbid obesity.

Further reading:

Tantalus, Restraint Theory, and the Low-Sacrifice Diet: The Art of Reverse Abstraction

Click here to read Dr Blair-West’s article on Restraint Theory.⁶

References:

Herva A, Laitinen J, et al. Obesity and depression: results from the logitudinal Northern Finland 1966 Birth Cohort Study. International Journal of Obesity 2006; 30: S20-S27.
Australian Institute of Health and Welfare (AIHW) Overweight and Obesity [online]. 2004 [cited 2008 February 27]. Available from URL: http://www.aihw.gov.au/riskfactors/overweight.cfm
Carpenter KM, Hasin DS, Allison DB, Faith MS. Relationships between obesity and DSM-IV major depressive disorder, suicide ideation, and suicide attempts: results from a general population study. Am J Public Health 2000; 90: 251–7.
Bjerkeset O, Romundstad P, et al. Association of adult body mass index and height with anxiety, depression, and suicide in the general population: the HUNT Study. American Journal of Epidemiology 2007; 167; 2: 193-202.
Lu XY. The leptin hypothesis of depression: a potential link between mood disorders and obesity? Current Opinion in Pharmacology 2007; 7: 648-52.
Blair-West GW. Tantalus, Restraint Theory, and the Low-Sacrifice Diet: The Art of
Reverse Abstraction. Medscape General Medicine. 2007;9(4):18.
NHMRC, Clinical Practice Guidelines for the Management of Overweight and Obesity in Adults, Commonwealth of Australia 2003. Available [online] at URL: http://www.health.gov.au/internet/wcms/Publishing.nsf/Content/obesityguidelines-guidelines-adults.htm/$FILE/adults.pdf