Common causes of obesity

The primary reasons weight gain occurs is due to genetic, hormonal and behavioural influences (and sometimes a combination of these). Medical conditions which produce genetic, hormonal and other symptom related causes are rare, however. The main reasons for the majority of obesity cases are almost entirely behaviourally related.

The most common reasons obesity occurs include the following:

• Leading a sedentary lifestyle (being inactive) – a person burns off far less calories through daily activity and exercise than are consumed daily.
• Consuming a non-nutritious diet or one that is higher in fats and calories and deficient in essential nutrients. Overeating goes hand-in-hand with poor diet. It has been noted that the type of foods consumed contributes greatly to rapid weight gain – with carbohydrates and sugars, as well as a variety of other processed beverages and food products all being common culprits. Poor nutrition is closely linked with lipid metabolism interferences. High levels of fructose (hypertriglyceridemia), which is normally metabolised in the liver, accumulate and cause a fatty liver. This results in problems with insulin, diabetes hypertension (diabetes related high blood pressure), and weight gain (obesity).
• Inadequate sleep which, often in combination with general physical activity, leads to hormonal changes (i.e. an increased production of Ghrelin, which stimulates appetite and a reduction in leptin which normally suppresses appetite) and unstable insulin levels, which affect hunger patterns (often causing a person to crave high-calorie foods).
• Genetic influences which affect how the body is able to process foods (energy), as well as how fats are stored. Research teams are looking at a potentially faulty gene, FTO which may cause certain individuals to overeat due to trouble being able to reach satiety.
• Aging bodies can result in a reduction of muscle mass and a slower metabolism, which makes it easier for a person to gain weight.
• Weight gained in pregnancy which is not under control or lost can lead to future excess weight problems, including obesity.
• Medical conditions such as polycystic ovarian syndrome (PCOS), Cushing’s syndrome, hypothyroidism (an underactive thyroid), osteoarthritis and Prader-Willi syndrome (excessive hunger) can all contribute to difficulties with weight control and lead to obesity. Conditions such as arthritis may prevent a person from being active, which can then also lead to weight gain.

Other contributing causal factors include:

• The use of certain medications
• Lower smoking rates / weight gain due to smoking discontinuation
• Self-perpetuating behaviours, such as binge eating
• Childhood sexual abuse and trauma