Obesity> Module 1

Attitude & Causes

Causes of obesity

In its most basic form, obesity is caused by an imbalance of energy in (food and drink) and energy out (basal metabolic energy consumption and exercise).

Drag the slider to tip the scales to indicate which you think is more closely associated with weight gain, or whether you think the two are equally linked to weight gain and then click submit to see some discussion:

scales

Although exercise has independent benefits that may even exceed the benefits of weight loss, weight itself is more closely associated with over eating rather than lack of exercise.

A recent study has shown that patients that believe that their obesity is cause by a lack of exercise are heavier than patients that believe their obesity is caused by what they eat.

To illustrate this point, a burger has about 500 calories, which is equivalent to one hour's high impact aerobics. If the burger is eaten with chips and a soft drink, this would require two and a half hours of high impact aerobics to burn off the calories if eaten in excess of daily metabolic calorie requirements.

burger (550 calories) equal to 1 hour high impact exercise
burger, chips and soft drink equal to 2.5 hours high impact exercise

Can this really explain the current obesity epidemic? This balancing of calorie input and output has always been the case. What has changed to cause the prevalence of obesity to triple over the last 25 years?

That being said, if we equate this to our knowledge about smoking and smoking cessation; although it is important to inform patients about the causes of lung cancer and COPD, for example through warnings on cigarette packaging, that is usually not sufficient to enable them to stop smoking. Likewise, telling patients that they need to eat less, is unlikely to be enough to support their efforts to lose weight.

Read more about the causes of obesity .

Explanation of causes

Click on each of the reasons below to see more information.

Biomedical reasons

Although the main reasons for the current obesity epidemic are sociocultural (such as our food environment) there are certain biomedical causes that should not be forgotten. Some can be managed through changes to medication, but others, such as genetics, can only be acknowledged and worked with.
  • Conditions: polycystic ovarian disease, hypothyroidism
  • Medication: antipsychotics, antidepressants, insulin
  • Genetics: differences in appetite and impulse control

Socio-cultural and environmental reasons

For many people food is a central part of socialisation, and rejecting food is rejecting generosity. For other people there may be status attached to weight, for example, HIV is known as the ‘slim disease' across much of Africa.

There have always been psychological and biomedical reasons for obesity, however these have not changed dramatically over time. The change that correlates most closely with the current obesity epidemic is environmental, with the availability of cheap calorie dense prepared food, that is high on flavour (salt, fat and sugar) and low on nutritional value.

  • Availability of cheap, calorie-dense, fast food
  • Food as an expression of care and generosity
  • Weight as an expression of health and wealth

Read more about poverty and obesity.


Psychological reasons

It is important however to distinguish between what may be simply a natural reaction to abundance and convenience from the rarer biomedical and psychological causes of obesity. We know that a history of trauma and emotional withdrawal is associated with binge eating disorder, and that there is an association between food insecurity and obesity.

  • History of abuse
  • Eating disorders
  • Food insecurity

Read more about sexual abuse and obesity.


We could extend this discussion to include many more issues such as perceived social norms, cost benefit, behavioural control, food insecurity, facilities and abilities, time, convenience, long working hours, single parenting, depression, lack of purpose and food as expression of care. For a comprehensive review, see the Foresight Report.