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Causes of Obesity Part 4 – Genetics

I remember years ago watching an interview with a very successful sportsman, whose parents had also been successful in sport. He was asked how much less work he’d had to do, coming into the sport with what was obviously a genetic advantage. His answer was memorable: “Sure, I have the genes to be good in this sport, but if all I did was sit around at home doing jigsaw puzzles, the genes wouldn’t make one jot of difference.”

Okay, so we’re not all world-class sportsmen here – but there’s a powerful grain of truth in his response. Good genes didn’t make him a champion – they only helped. Doing all the hard work was what made him a champion. In terms of the causes of obesity, the same principle applies – genetics make a contribution, but for most of us, they’re not the beginning and end of the story. Other factors also play a part. Some of those factors might have no relationship to the genes, but others might have a direct effect.

Not only that, but the role genetics plays in obesity is still currently under a great deal of scientific investigation. I suspect they’re all looking for the magic gene that switches off weight gain. I have no idea how they’ll go with that, but I’m sure we’ll find out.

Genetic Causes

  1. The scientific world was rocked in 2007, by the discovery of a gene that directly effects weight gain. The presence of the gene can help explain why some people put on weight easily while others don’t. The gene is called FTO, and having the weight gain version of it means you are a staggering 70% more likely to be obese!  According to the study, 1 in 6 people had this version of the gene, which could go some way to explaining the ‘obesity epidemic’ we keep hearing about. But don’t go hanging your hat on this research – in this particular study, the weight gain difference averaged out at 3kg – ie, people who had the gene only gained an average of 3kg more than those who didn’t, although they did have around 15% more body fat. On the bright side, subsequent studies showed that exercise reduced the chances of the gene having complete control.
  2. A completely unrelated study at the Boston University School of Medicine discovered another genetic variation called Brd2, which caused severe obesity – but not diabetes. Given how common it is for diabetes to occur in severe obesity, this result deeply surprised the researchers. This study was done with mice – and despite the enormous amounts of weight they put on, they still continued to exercise as much as their thinner counterparts. But despite the exercise, they lost no weight.
  3. In 2010 another shocking discovery was made in a study from the Imperial College London, which discovered that 7 in every 1000 morbidly obese people were actually missing parts of their DNA – parts that were never missing in normal weight people. The missing parts contained approximately 30 genes. The researches believe that there are other missing genes that contribute to obesity, along with mutations of existing genes that have a similar effect. Parents of those studied who also had the missing genes were also obese.
  4. Yale University has also made some striking contributions to the discussion. They suggest that weight is set in the brain before birth. “Neurons that are supposed to signal when you’ve eaten enough and when to burn calories, are much more sluggish because they are inhibited by other cells.” They go on to admit that this supports the argument that weight loss is less about personal will and more about brain development.

There are, of course, a number of severe genetic abnormalities that cause excessive weight gain, but they also cause other serious health conditions which, to be honest, you’d know about it you had them. What I’ve listed here is just the tip of the iceberg when it comes to how your genes affect your weight gain or loss. The message here is – don’t rule out your genes, but don’t go resting on them as well. You may have some genetic issues, but they will only play a part in your weight problems. If you want to know more, I suggest talking to your doctor as a starting point.

In the next part of Causes of Obesity, I’ll be looking at how our daily habits can directly influence how we put on weight. And I’m not just talking about eating habits 🙂

Read the rest of the Causes of Obesity Series:

Part 1 – The Real Causes of Obesity

Part 2 – 11 Ways Your Body Makes You Over-eat

Part 3 – Eating Disorders Start Young

Part 5 – Bad Habits

Part 6 – Clinical Issues


1. JAMA and Archives Journals (2010, April 8). Exercise associated with reduced effects of obesity gene in teens. ScienceDaily. Retrieved October 17, 2010, from http://www.sciencedaily.com/releases/2010/04/100406205027.htm

2. Boston University Medical Center (2009, December 22). Discovery of new gene called Brd2 that regulates obesity and diabetes.ScienceDaily. Retrieved October 17, 2010, from http://www.sciencedaily.com/releases/2009/12/091214201007.htm

3. Imperial College London (2010, February 4). Some morbidly obese people are missing genes, shows new research. ScienceDaily. Retrieved October 17, 2010, from http://www.sciencedaily.com/releases/2010/02/100203131401.htm

4. Yale University (2010, August 5). One high-fat diet, two different outcomes: The path to obesity becomes clearer. ScienceDaily. Retrieved October 17, 2010, from http://www.sciencedaily.com/releases/2010/08/100802151315.htm

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Related posts:

  1. The Real Causes of Obesity – Part 1
  2. Causes of Obesity Part 2 – 11 Ways Your Body Makes You Over-Eat
  3. Natural Appetite Suppressant
  4. Causes of Obesity Part 3 – Eating Disorders Start Young


  1. KRin says:

    The Cochrane database of studies is available free to Australian citizens (no, I don’t have the URL) and the Medical Journal of Australia also (as far as I remember) if you would like to check out further information.

    1. Mackenzie says:

      Thanks for that KRin. It’s amazing just how much information is out there. I’ll take a look.