Obesity links to prostate cancer confirmed

From New Atlas

Obesity increases a man’s risk of dying from prostate cancer, according to a massive new study by researchers in the UK, however, the causal mechanisms underpinning the link are not yet clear.

Prostate cancer is one of the most common forms of cancer to be detected in men. It is a slow-growing form of cancer, so patients can live many years after diagnosis. In fact, many patients diagnosed with prostate cancer ultimately die of other causes before the cancer develops enough to cause its own problems.

Because of the prevalence of this kind of cancer, researchers have been working to understand what factors may contribute to the development of more aggressive types of prostate cancer. Aurora Perez-Cornago, lead on the new research from the University of Oxford, said knowing the risk factors for fatal prostate cancer could help patients avoid certain damaging lifestyle practices.

“Knowing more about factors that increase the risk of prostate cancer is key to preventing it,” said Perez-Cornago. “Age, family history and black ethnicity are known risk factors but they are not modifiable, and so it is important to discover risk factors that it is possible to change.”

Excess body fat has previously been linked to higher rates of fatal prostate cancer. This new research set out to get a clearer insight on the association between body weight and prostate cancer by conducting a meta-analysis of 19 prior studies, including data from more than 2.5 million men.

The overall finding affirmed prior suspicions, with higher volumes of body weight linked to higher rates of fatal prostate cancer. Quantifying that increased risk the research found for every five point rise in body mass index (BMI), a person increased their risk of dying from prostate cancer by 10 percent.

The association between body weight and fatal prostate cancer was independent of where a person’s body weight was concentrated. But the researchers did calculate a seven percent increase in risk of dying from prostate cancer for every 10-cm (3.9-in) increase in waist circumference. Looking at UK data the study estimated around 1,300 fewer people would die from prostate cancer every year if the average BMI of men dropped by five points.

Perez-Cornago said the link between body weight and fatal prostate cancer may be clear but it still is not known what could be driving the association. It is plausible to suggest higher volumes of body fat may be driving the progression of prostate cancer. In fact, a 2018 study did hypothesize a mechanistic link between dietary fat and the metastatic progression of prostate cancer.

But the researchers also indicate other factors are likely playing a role, including differences in cancer detection between obese men and those with a healthy weight. Prostate-specific antigen (PSA) concentrations in blood samples, for example, can be lower in subjects with high BMI, meaning cancers may be detected at later stages leading to worse outcomes.

“More research is needed to determine if the association is biologically driven or due to delays in detection in men with higher adiposity,” said Perez-Cornago. “In either case, our latest results provide another reason for men to try to maintain a healthy weight.”

The new study was published in BMC Medicine.

Source: The European Association for the Study of Obesity

A remarkable new weight-loss drug

From Melbourne's The Age newspaper

Scientists and advocates say new anti-obesity drugs generating remarkable levels of weight loss in clinical trials will once and for all dispel the myth that obesity is simply the result of making unhealthy choices, rather than a genuine disease.

The emergence of the new drug, marketed locally as Wegovy, promises to revolutionise weight-loss treatments. In one major clinical trial patients using the drug lost 11 per cent more body weight than those undergoing an intensive diet and exercise program.

Scientists and campaigners have long rejected the popular narrative that obesity is solely the result of unhealthy choices. Wegovy’s dramatic results might provide the sort of black-and-white proof that convinces society at large, they hope, that it is a disease and needs to be treated as such.

“I think it will reframe the argument. As these drugs become more effective and available, it will be harder for people to ignore them,” said Professor Brian Oldfield, a leading obesity researcher at Monash University and editor of the field’s top academic journal.

Tiffany Petre, director of the Obesity Collective, said she “hopes this drug changes conversations about obesity in society”.

“People with obesity haven’t been able to get appropriate healthcare. Now there is something on the market.”

Governments around the world have poured hundreds millions of dollars into public health campaigns that aim to tackle obesity by encouraging healthy eating and exercise.

Then-prime minister John Howard in 2004, for example, rolled out a $116 million program to pay for after-school sports and healthy-eating education for families – while also rejecting plans to ban fast-food advertising in children’s TV programs.

While healthy eating and physical activity are vital for good health, decades of evidence suggest they simply do not lead to large amounts of weight loss, said Oldfield. “They are not enough by themselves. They typically give a 3 to 5 per cent reduction in body weight.”

This problem shows up in a large trial of Wegovy published in JAMA early last year. Some 611 volunteers were given ‘Intensive Behavioral Therapy’: eight weeks on a supervised very-low-calorie diet, followed by more than a year of a low-calorie diet.

They were also asked to do 100 minutes of exercise a week, eventually increasing to 200 minutes, and received 30 visits from a dietitian. “That’s extreme and unsustainable,” said Oldfield.

After this enormous effort they lost, on average, 5.7 per cent of their body weight. A subgroup who did all this and took Wegovy lost 16 per cent of their body weight – an average of 16.8 kilograms.

Wegovy, which was approved by Australia’s medicines regulator for weight loss last year, mimics a natural hormone that slows down how fast the stomach works, making people feel fuller for longer. It also seems to affect how the brain regulates appetite.

The drug does come with side effects – particularly nausea – and in clinical trials about 6 per cent of volunteers are forced to drop out. Experts caution it is not a silver bullet and must be used alongside diet and exercise.

Several years ago, Professor Stephen Simpson, director of the Charles Perkins Centre at the University of Sydney, and his team ran a series of focus groups looking at how to change people’s opinions about the cause of obesity.

“People have this deep-seated view it is their fault, particularly those with living experience. It’s deeply held and pervasive,” he said. (Oldfield has received fees from the drug’s sponsor Novo Nordisk, as has Obesity Australia; Simpson sits on that organisation’s board).

This stigma has even shown up in the response to recent Wegovy shortages, said Simpson, with some seeking to blame people with obesity for seeking medical treatment for their condition.

The most-effective tool, he found in his focus groups, was to “smash the frame” – to disrupt people’s idea that obesity was caused by predominantly by bad choices.

“One of the most powerful ways of pushing back against that, we found out very quickly, is to say it is biological. There is a powerful biology that underpins obesity.” The success of Wegovy, he said, “is clearly indicating there is a profound biological underpinning”.

Calorie consumption

An interesting chart from Business Insider/ Credit Suisse in this article

If you look at photos from the 20s, 30s , 40s and 50s hardly anyone was fat, let alone grotesquely obese. According to this wikipedia article, a 24 year old man weighing 80kg doing moderate exercise would need to consume roughly 3000 per day to keep his weight stable.  But if he did no exercise, he would have to restrict his intake to 1900 calories.  Since over the whole period depicted in the chart, consumption exceeded 3000 calories a day, it must have been exercise which kept them thin.

So it's not just the rise in calorie consumption which has led to the obesity epidemic.  It must also be the decline in exercise.  I don't mean going to gyms, I mean that 60 years ago ppl walked more, mowed the lawn with manual mowers, climbed stairs, got out of the car to open the garage, etc.  I used to cycle 10 k's to school each way.  And so on.

It won't be enough to cut calorie consumption.  We will also have to start to exercise in the way our grandparents and great grandparents did.  And (sorry, but there it is) the best way to cut calories is to adopt a mostly vegetable diet.