Updated 14 March 2014

Are fat people just greedy and lazy?

People stay fat because they lack the self-discipline to exercise or eat less. This is a common misperception or ‘conventional wisdom’.

If it were true that eating too much and lack of exercise were the primary causes of obesity, then we shouldn’t find thin or normal weight people who eat too much and don’t exercise. And yet we all probably know people who eat what they like and don’t exercise and don’t put on weight.

“Research is in fact increasingly indicating that people with weight issues (particularly central obesity) are fat not because of laziness, lack of discipline or greed. Rather the majority of them have a metabolic dysfunction called insulin resistance. This means that they have sustained high levels of insulin preventing the efficient burning (oxidation) of fat,” says Dr Peter Hill of the Met-S Care Program.

Biology affects behaviour

A simple explanation for weight gain and retention is the condition that results when fat production and storage exceeds the breakdown and burning of fat as fuel for energy for vital bodily functions.

Dr Hill adds, “What has become clear, thanks to our increasing knowledge of human biochemistry, is that obesity is generally not a problem of psychology (‘willpower’) but of physiological psychology – the effect biology has on perception and behaviour.”

When someone who is overweight or obese due to a metabolic dysfunction, this is because the body is not regulating fat cells properly. Hormones and enzymes are particularly important in directing fat metabolism – how the body choses to create, breakdown or burn fat. When these hormones and enzymes aren’t working properly this system becomes faulty and fat is not metabolised appropriately, leading to fat storage (weight gain and weight retention) rather than being used for energy.

Hormones and the role they play


The most important hormone in this process is insulin, the ‘fat building’ hormone. Insulin has two key functions – it determines how our body uses carbohydrate (glucose), and it plays the key role in fat metabolism - both fat building (storage) and breakdown (burning for energy). The conversion of excess glucose into fat and subsequent storage in fat cells is facilitated by insulin.

The hormone insulin, when at normal levels in the body, helps the body to convert fat in cells into energy Ironically it gets in the way by slowing this process down if the body’s insulin levels are too high.

Chronically high levels of insulin lead to a metabolic condition known as insulin resistance, which is when insulin receptors on the surface of cells lose their sensitivity to insulin. This dysfunction leads to higher than normal levels of insulin in the blood. High levels of insulin prevent the optimal mobilisation or release of fat from the fat cells (lipolysis) and its subsequent oxidation (fat burning).


Leptin is the hormone that tells our brain that our fat cells are full. High levels of insulin also interferes with the leptin signalling in the brain. When the brain can’t ‘see’ the leptin signal it ‘tells’ the body to increase energy stores, leading to overeating, and ‘tells’ the sympathetic nervous system to conserve energy and reduce activity, seen as ‘laziness’. A double whammy! 

Insulin balance

As insulin is the primary regulator of fat storage and utilisation, it follows that re-establishing insulin balance is key in terms of both obesity prevention and reversal or therapy.

Insulin secretion is mostly controlled by blood glucose levels - largely affected by carbohydrate and, to a lesser extent, protein in the diet. Importantly, fat has little or no effect on blood sugar levels and therefore, little or no effect on insulin secretion.

Sugars and other refined carbohydrates are able to raise blood glucose and therefore raise insulin levels with a minimum of metabolic effort. For those with Metabolic Syndrome or dysfunction, these raised insulin levels influence the biological and resultant psychological effects that prevent weight loss.

Getting insulin levels to within normal levels is thus essential and can be achieved by cutting out sugar and other refined carbs.

In the next article we will consider just why it is so important to treat and prevent Metabolic Syndrome.
Met-S Care works with Dis-Chem Pharmacies to empower people living with Metabolic Syndrome to take control of their condition. Read more.

References available on request.