• Ever wondered by, despite your best dieting efforts, you can't shake those kilos? Maybe it's because you have a genetic propensity to be overweight? (Science Photo Library RF/Getty Images)Source: Science Photo Library RF/Getty Images
If you've tried every salad, shake, pill and exercise regime going around, but find that the kilos still aren’t budging, it can be extremely disheartening. But what if you learned that the secret to losing weight was not down to your lifestyle habits - perhaps it's all in your genes?
Emily Nicol

28 Aug 2017 - 11:42 AM  UPDATED 8 Sep 2017 - 2:21 PM

What happens when, despite your heroic efforts to lose weight through a good diet and exercise, healthy food and regular gym sessions just aren't enough? Do you blame it on your genes and shift your focus from lifestyle changes to more alternative measures? 

At Melbourne’s Austin Health, a world leader in the field of obesity, Professor Joe Proietto runs the Weight Control Clinic. Here, obesity is approached as a disease, not a lifestyle choice caused by bad food or laziness. And as a result, his team is helping to successfully treat people with the condition. 

“The prejudice that exists towards the obese is reflected in the fact that there are no medications on the pharmaceutical scheme for obesity,” says Prof Proietto in the documentary series on SBS this September, The Obesity Myth. 

"The assertion that obesity is genetic is controversial. However the evidence is very strong to say there is a genetic predisposition to obesity.

Prof Proietto says that there are 100 genes that affect weight in humans but five in particular that are evident in the morbidly obese. And ultimately it’s these five genes that "all lead to an increased drive to eat”.

In hunter-gatherer times, being hungry meant survival, he explains. “The motivation to hunt, gather and forage was actually a genetic advantage. Nowadays, with cars and drive-throughs, the simple ratio of calories in and calories out is completely out of balance, there is no long trek to find food and once it’s found, there is comparatively lower nutritional value.

Professor Robert Wilson, a senior surgeon with the Sydney Institute for Obesity Surgery (SIOS) believes that the rates of obesity in lower-socioeconomic locations demonstrate this point. “If you look at the cost of food, fast food is cheap and healthy food tends to be a little bit more expensive so, we have higher levels of obesity in the western suburbs of Sydney - some of the highest in Australia in fact are found around the Campbelltown, Blacktown Nepean areas.”

There are also certain groups within the population that are more likely to present with obesity, in particular those that have only recently been exposed to western diets.

“Racial background can be a big risk factor. For instance those with Polynesian background, First Nations people in North Americas and Australian Aboriginals don’t tend to be necessarily obese when they live in traditional ways with a traditional diet. When they are exposed to western diets however, they have higher levels of obesity and metabolic syndrome which is high blood pressure, high cholesterol, obesity, obstructive sleep apnea, and coronary artery disease. All of those things that are related to obesity."

Again, that comes back to genetics.

“When patients are exposed to a sedentary lifestyle or a lifestyle which involves high amounts of highly processed carbohydrates, they will develop metabolic syndromes.”

SIOS also see a higher proportion of female patients, women who have gained weight through childbearing, those with hormonal complications such as Polycystic Ovarian Syndrome and some that have nutritional issues after cancer surgery. In these cases, the holistic approach to weight loss is required and increasingly, treating underlying hormonal issues and even psychological complications as part of a patient’s plan is becoming the norm.

"...when a patient gets to an elevated BMI, particularly above 40, their body resets the set point at which the body itself likes to keep the weight at.”

“If we look at conventional weight loss programs, where we change people’s diets and encourage them to do more exercise, the success rate after a 12 month period is very low – and the reason for that is when a patient gets to an elevated BMI, particularly above 40, their body resets the set point at which the body itself likes to keep the weight at.”

Your body has a mechanism by which it maintains your weight at its fattest stable weight and there’s lots of different times in life when set points are set - it’s what your body thinks is healthy for your height and weight.

“For example, if you have a woman whose ideal weight is 60 kilos, but she then has three children, gets gestational diabetes and puts on 40 kilos, even on a rigorous program where calories are restricted and more exercise is taken, the body will think that you are starving and it will increase your appetite to compensate, trying to keep you at a set point.”

Once again, hormones and genetics will make it near impossible to keep weight off for good in a percentage of the community.

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Bariatric (Gastric bypass) surgery has proven to be one of the most successful ways to prevent weight loss patients from re-gaining what they have lost by not only reducing the size of the stomach, but the amount of the hormone that causes hunger which is produced in the stomach: ‘ghrellin’.

“It’s very important we modify patient’s lifestyle and food choices as it’s much more likely to have a successful outcome. There are different types of bariatric operations where we restrict the volume of food that people are able to eat – but if those patients then don’t change their lifestyle they won’t have a successful outcome.

“For example, if you have a patient who eats cheese and chocolate and ice cream, those are all foods that are easy to digest because they melt, but they’ve got a huge amount of calories in them.”

Once again, hormones and genetics will make it near impossible to keep weight off for good in a percentage of the community. 

The diet prescribed at both the Austin Clinic and SIOS tends to be carbohydrate restrictive.

Prof Proietto explains why: “once the body is starved of carbs, our livers are forced to burn stored fat.” This then creates an environment in the body where more ketones are produced, critical in being able to burn fat.

Though this process of changing the body internally and influencing hormone levels can take years, the outcome could be overwhelmingly successful.

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'The Obesity Myth', a new three-part documentary series which challenges the commonly held view that obesity is the result of lifestyle choice, premieres at 7:30pm, Monday 4 September on SBS. Each episode will also be available on SBS On Demand after broadcast. 

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