Increased consumption of high-calorie processed foods and a shift towards sedentary lifestyles has resulted in an increasing rounder population across the world. We are in the grip of a global epidemic. It is estimated that by 2020, obesity will be the single biggest killer on the planet.
Obesity rates have risen at least threefold since 1980 in some areas of North America, the UK, Eastern Europe, West Asia, the Pacific Islands, Australasia and China. Developing countries like India are facing a dual health burden, with obesity coexisting with malnutrition. A survey of 83,000 Indian women found that although 33% of them were malnourished, 12% were overweight or obese.
Of particular concern is increasing child obesity, especially in Asia. Urbanisation in China has led to harvesting an unhealthy lifestyle — the Chinese government says one in 10 city-dwelling children suffers from obesity. In Japan, obesity among nine-year-old children has tripled. While we do not have consolidated figures for India, doctors say they are witnessing a clear trend towards rising obesity among children. We now know that the biggest global health burden we are facing is dietary in origin, compounded by association with low physical activity levels.
Research has shown that there is a bi-directional association between mental health issues and obesity, with an entrenched impact on the risk factors associated with both. There are also implications of psychological distress caused by weight-related stigma and discrimination. Evidence suggests that people with mental health issues are more prone to obesity.
Compared to adults with normal weight, adults with a BMI over 30 are more likely to be diagnosed with coronary heart disease (CHD), hypertension, stroke, high cholesterol, gout, osteoarthritis, sleep problems, asthma, skin conditions and some types of cancer. Obesity is an important causal factor in type 2 diabetes, and it complicates its management, making treatment less effective.
Obesity may also trigger a series of psychological disorders, including depression, eating disorders, distorted body image, and low self-esteem. Binge eating may explain, at least in part, the relationship observed between obesity and depression. This may be because binge eating could contribute to weight gain and obesity, which, in turn, may negatively affect mood. Furthermore, recurrent episodes of binge eating are extremely unpleasant for those who experience them and may put the individual at higher risk of clinical depression.
The relationship between obesity and mental health issues is a complex one. Some researchers suggest that obesity can lead to mental health problems while others have found that people with such problems are more prone to obesity. Other studies have found no association between the two.
Results from the most recent systematic review of longitudinal studies point towards bidirectional associations between depression and obesity. Another recent systematic review and meta-analysis found a weak but positive association between obesity and anxiety disorders.
Obesity is also associated with an increased risk for a variety of chronic diseases, most of which are associated with depression that, in turn, can precipitate chronic disease due to diminished treatment adherence and/or response. There are a number of mechanisms that could explain potential casual associations between obesity and mental health issues:
• Both obesity and mental health disorders account for a significant proportion of the global burden of disease.
• Mental health of women, than men, is more closely affected by overweight and obesity.
• There is strong evidence to suggest an association between obesity and poor mental health in teenagers and adults. This evidence is weaker for younger children.
• The perception of being obese appears to be more predictive of mental disorders than actual obesity in both adults and children.
• Weight stigma increases vulnerability to depression, low self-esteem, poor body image, maladaptive eating behaviours and exercise avoidance.
Increased medical problems and mobility restrictions associated with obesity have a direct impact on psychological well-being, leading to depression, eating disorders, a distorted body image and low self-esteem. There is less research on the mechanisms that may cause adults with mental health disorders to become obese. It has been suggested that poor mental health can lead to unhealthy lifestyle choices and increased appetite.
A combination of the biological effect of increased stress and poor adherence to weight loss programmes, binge eating, negative thoughts and reduced social support, may make it difficult for a depressed person to avoid weight gain. There is also evidence that people with chronic or repeated episodes of depression are at particular risk of subsequent obesity.
There is an urgent need for evaluation of weight management interventions, in terms of both weight loss and psychological benefits, to help physicians and psychologists better deal with obesity-related mental health problems. We need to develop a better understanding of the two-way link to develop improved curative practices to address this increasing burden.
(The writer is an expert on mental health and Director, Poddar Wellness Ltd)