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Can obesity really be ‘in your genes’?

The truth behind the headlines – is it possible to pass obesity down through generations?

Legendary actress Audrey Hepburn is not someone commonly associated with obesity. Throughout her adult life she was rail thin. But she grew up in the Netherlands and fell victim to the Dutch Famine of 1944. This famine would later shed light on how the genes involved in laying down fat cells can respond to dramatic changes in environment.

audreyhepburnDuring the famine, the Nazis confiscated food and fuel to heat homes. People starved and froze to death in the streets. Audrey, then 15, would stay in bed and read to take her mind off the hunger. She suffered from malnutrition, acute anaemia, breathing problems and oedema (swelling in the body). She was dogged by illness all her life and died in her mid sixties from cancer.

Among other things, clinical studies on the Dutch Famine later found that pregnant women who had been malnourished early in pregnancy had babies with a low birth weight. But those babies went on to become fatter adults in later life, with higher than average obesity rates.

This is believed to be an example of a process called epigenetics. The theory is that our genes are not set in stone (as previously thought), but can be switched on and off depending on environmental factors. We’ve historically viewed DNA as if it’s a permanent set of instructions, but it’s actually more like a script. Cells read the genetic code in DNA and, subject to environmental factors, they may see that code differently. For example, recent studies suggest fathers can pass their obesity down to their children through their sperm and should be following the same healthy lifestyle advice as women when they are looking to conceive. This constitutes epigenetics in motion.

Many overweight and obese people have claimed their obesity comes down to their genes. And true enough, obesity does, to some degree, appear to run in families. But is this purely because unhealthy eating habits tend to be shared by family members or does it come down to our biology?

There are a number of studies which point to genetic markers in obesity. But they’re not nearly as dramatic as some of us might think. A recent study by scientists at the University of Michigan explored the genes of 300,000 people. Their findings suggest that up to one in five people has slightly faulty wiring when it comes to the stomach signalling to the brain that it’s full. This means those individuals affected are likely to have bigger than average appetites because it takes the brain longer to register a sufficient portion has been eaten.

Professor Alistair Hall, a cardiologist at Leeds University, says the study shows that for some people restricting food is harder, in the same way that some people find it more challenging to limit their drinking. “Some people are potentially more addicted to food,” he said. “They simply find it harder to suppress their appetite.”

"Some people are potentially more addicted to food. They simply find it harder to suppress their appetite."

Professor Alistair Hall, Cardiologist, Leeds University

However, there doesn’t appear to be conclusive proof that some of us simply lay down far more fat cells than others. Indeed, contrary to popular opinion, our metabolisms are only thought to vary marginally.

Whatever the case, all of the existing evidence about so-called ‘obesity genes’ is but a crumb in a sandwich of evidence that shows human beings of all shapes and sizes can and do get on top of their obesity if they access the right resources. We can choose to challenge our family’s apparent tendency to put on weight at the drop of a pie crust. We don’t have to eat rubbish, tuck into second portions or use the vending machine at work between meals. We can stop and notice that while our brain appears to be telling us we are hungry, we are in fact physically full.

"The notion that our fat is indelibly inscribed in our genes was directly derived from the now outdated scientific concept know as genetic determinism, which would have us believe that we are victims of genetic forces outside of our control."

Dr Bruce Lipton, Stem Cell Biologist

Dr Bruce Lipton, a stem cell biologist, discusses epigenetics in his groundbreaking book ‘The Biology of Belief’. He writes: ‘The notion that our fat is indelibly inscribed in our genes was directly derived from the now outdated scientific concept known as genetic determinism, which would have us believe that we are victims of genetic forces outside of our control. Unfortunately, the assumptions of powerlessness are a one-way street to personal irresponsibility. Too many of us have said: “Hey, I can’t do anything about it anyway, so why should I care? Overweight? It runs in my family. Pass me the bonbons.”

You are in control of your decisions; you have the power to make a change. Find out how CBT helped Sarah change her behaviour towards food.