This is part of the Healthy Weight Management Series of articles, tips, blogs and videos which is available on the Sunset Coast Hypnotherapy Facebook page between 25 April and 28 July.

The influence of genetics in weight gain

Many people blame their genes for weight gain. But how true is this?

belly-2473_1280More than 400 different genes have been implicated in the causes of overweight or obesity, some having more effect than others on obesity (1).  Genes can contribute to obesity in many ways, by increasing appetite, decreasing the sense of fullness, by decreasing the metabolism, and making food cravings more likely. They also influence the body-fat distribution, and the likelihood of using eating as a way to cope with stress.

Genetic influence accounts for 25% to 80% of the predisposition to be overweight (1). The Royal Australian College of General Practitioners reported that using studies on twins, it has been found that 40–80% of variation in body fatness is attributable to genetic differences between individuals. In addition, the reported heritability of body mass index in these studies was around 70–80% (2).

It has been discovered that severe obesity in a child is due to defective production of a hormone, leptin, by the leptin gene in fat cells. This can be treated with leptin. Lack of leptin produces (amongst other effects) over-eating, and all effects are reversed by the replacement of leptin (4). Several studies have shown that carriers of so-called obesity genes consume on average 125-280 kcal a day more and have no differences in their metabolic rates (6).

A study of adopted children found that the children were more likely to be thin if their genetic parents (whom they had never met) were also thin, and vice versa. There was less of a resemblance (thin or fat) to the adoptive parents who they had lived with (5).

The Harvard Medical School (1) states that

“genes may be a significant contributor to your obesity if you have most or all of the following characteristics:

  • You have been overweight for much of your life.
  • One or both of your parents or several other blood relatives are significantly overweight. If both of your parents have obesity, your likelihood of developing obesity is as high as 80%.
  • You can’t lose weight even when you increase your physical activity and stick to a low-calorie diet for many months.

Genes are probably a lower contributor for you if you have most or all of the following characteristics:

  • You are strongly influenced by the availability of food.

  • You are moderately overweight, but you can lose weight when you follow a reasonable diet and exercise program.

  • You regain lost weight during the holiday season, after changing your eating or exercise habits, or at times when you experience psychological or social problems.”

This tends to suggest that even if you are predisposed to be overweight, that it can be overcome with effort.

Thrifty genes

Around 85% of us carry ‘thrifty genes’ that can help us store body fat. These were necessary for our ancestors to survive during times when food was in short supply. Now, of course, this is not an issue, and food is available whenever we want it, 24 hours per day (1).

Some people with a strong genetic predisposition to obesity may not be able to lose weight with the usual forms of diet and exercise therapy. They are less likely to maintain weight loss. It is worth knowing that for those people with a very strong genetic predisposition, sheer willpower is ineffective in counteracting their tendency to be overweight, and they may need weight-loss drugs or surgery (1).

Individuals with strong genetic predisposition to obesity may also be helped by hypnotherapy to change the type and amount of food that they wish to eat.

Environmental causes of obesity

These can also play a large part in obesity. These include anything in our environment that makes us more likely to eat too much or exercise too little. Taken together, experts think that environmental factors are the driving force for the dramatic increase in obesity (1).

Environmental influences come into play very early, even before babies are born. This is called “foetal programming.” If a mother smokes during pregnancy or has diabetes, her baby is more likely to become overweight than if she didn’t smoke or have diabetes.  Researchers believe these conditions may somehow alter the growing baby’s metabolism in ways that show up later in life (1).

Breastfeeding also helps safeguard against obesity. Babies who are breast-fed for more than three months are less likely to have obesity as adolescents compared with infants who are breast-fed for less than three months. Tastes for unhealthy foods can also be started in childhood. Children who drink sugary drinks and eat high-calorie, processed foods tend to continue eating them as adults, promoting weight gain (1). Training in good nutrition, and exposure to a wide variety of foods can also assist in maintaining a healthy weight (6)

Lack of activity can also start in childhood, e.g., children who watch television and play video games instead of being active may be programming themselves for a sedentary future (1)

The amount of sleep that we get, our stress levels, and other psychological factors can affect weight as well (1).

Conclusion

However, the good news is that food preferences can change. The brains of obese and normal weight people were scanned to record their reactions to food. The reward centres in the obese peoples’ brains showed a strong reaction to high-fat foods (fast food, sweets). The test was repeated after the obese and normal weight people had followed a dietary plan containing healthy, low-calorie foods for several months. The reward centres in the obese subjects’ brains reacted more strongly to these foods in the second test (6).

Ultimately, our genes just set our ‘default’ direction that we will follow if we don’t intervene with eating a variety of healthy foods. For some people, keeping off the genetically predisposed path to obesity is harder than for others, and required more effort than for their naturally thin friends.

As described above, the good news is that the efforts to maintain healthy behaviours  are only temporary: once we have become habituated to new behaviours, we no longer have to struggle to maintain them (6).


If you would like more help with motivation or other tools to assist in weight loss, or simply wish to find out more information, please email me (Lisa) on sunsetcoasthyp@gmail.com. I will do my best to answer any of your questions, and to help you decide if I am the best therapist for you. All with no obligation.


References

(1) https://www.health.harvard.edu/staying-healthy/why-people-become-overweight

(2) https://www.racgp.org.au/afp/2017/july/genetics-of-obesity/

(3) https://www.bmj.com/press-releases/2012/09/10/what’s-main-cause-obesity-–-our-genes-or-environment

(4) Farooqi SI. Genetic, molecular and physiological mechanisms involved in human obesity: Society for Endocrinology Medal Lecture 2012. Clin Endocrinol (Oxf) 2015;82(1):23–28. Link.

(5) Stunkard AJ, Foch TT, Hrubec Z. A twin study of human obesity. JAMA 1986;256(1):51–54. Link

(6) https://www.theguardian.com/society/2019/jan/05/truth-obesity-five-fat-myths-debunked

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