The Genetics of Weight Management

According to the Heart and Stroke Foundation of South Africa, the nation is in the grip of a countrywide obesity epidemic. Somewhere between Banting, The Blood Type diet, green smoothie cleanses, Paleo, maple syrup cleanses and the Holford Low GL Plan, we must be doing something wrong. It is time to face the stats and learn more about weight management.

South Africa has the highest overweight and obesity rate in sub-Saharan Africa, with up to 70% of women and a third of men being classified as overweight or obese.¹ A staggering 40% of women in our country are obese. South Africa is among the countries with the highest childhood obesity rates – one in four girls and one in five boys. Children from wealthier families have the highest rate of both increase and prevalence of obesity.²

What these staggering rates mean is that somewhere between Banting, The Blood Type diet, green smoothie cleanses, Paleo, maple syrup cleanses and the Holford Low GL Plan, we must be doing something wrong. Or you must be doing something wrong because your husband has lost 20 kg and you’ve gained 3 kg.

YOU ARE UNIQUE

The truth is, as much as Banters and Blood Typers would have you believe their diet is best, it may not be the best diet for you. That’s because your genes dictate how you react to food and exercise more than the diet of the moment, or the diet with the best propaganda campaign, ever will.

To prove my point, we need to look at some Japanese research. A 24-month weight loss programme enrolled 154 men. Compliance within the group to the diet and exercise plan was considered excellent. At the end of the programme, the men were divided into four groups depending on their weight loss and maintenance. This ranged from successful weight loss and maintenance over 24 months, to slower weight loss and finally to those who lost almost no weight at all despite excellent compliance. That’s right – all 154 men were compliant yet some lost hardly any weight at all.³

So we go back to you and your husband again. He’s positive that you’ve been snacking on chocolate when his back is turned. You, on the other hand, are feeling deprived and depressed. You’ve been the strictest you’ve ever been on a diet but another week has gone by and you haven’t lost even 0.5 kg.

THE KEY TO WEIGHT MANAGEMENT

Traditionally, clinical management of obesity has focused on energy balance, most times ascribing any resistance to losing weight as due to excess calories, lack of exercise, or a low metabolic rate. This is a simplistic and outdated interpretation. If an individual’s susceptibility to obesity and responsiveness to weight loss interventions are to be understood, then the issue needs to be addressed at a molecular and metabolic level, including genetic interactions.⁴

GENETICS, THE ENVIRONMENT AND GENETIC TESTING

Genetics determines your susceptibility to a condition like obesity. Environmental factors such as diet and exercise determine who among those that are genetically susceptible will develop the disease.

Nutrition is an environmental factor of major importance. While your genes may determine how your body handles foods like fats and carbohydrates, your ability to choose foods that best suit your genes will help with weight loss, but also with optimal health and disease prevention.

What this means is that weight regulation is not just about calorie intake. It’s an integral play between genes that control metabolism, the way fat tissue behaves, the way the body produces heat, the immune system, food intake, eating behaviour, satiety and hunger. Nutrigenetic tests look at a collection of genes involved in all of these processes. Based on the results, a trained healthcare practitioner will be able to better recommend an eating and exercise plan best suited to you.

Genes involved in the following processes are usually tested:

• Regulating energy intake – many of these are obesity genes which play a role in satiety. This means that if you have variants in these genes, it may take you longer to feel full because you have a tendency to overeat. People with variants in these genes have a higher risk of becoming overweight and developing obesity and diabetes. However, recognising your risk factors may help you to modify your diet and eating behaviour.
• Fat burning and adipogenesis – some of these genes affect how your body responds to and uses fat. Depending on how many variants you have in these genes, a high fat diet (like Banting) may not be the best for you.
• Thermogenesis – these are genes that control energy expenditure. For people who have variants in several of these genes, calorie restriction becomes a necessity. Variants in these genes also determine how you respond to exercise.
• Inflammation – these are genes that control interactions between adipose tissue (fat tissue), inflammation and immunity. Variants in these genes may determine whether a low-carb or high-fat diet is right for you because variants in some of these genes can predispose you to inflammation and its associated conditions like obesity and insulin resistance.
• Transcription factors – variants in these genes will influence the amount of fat, fibre and calories you should have in your diet. Some of these are genes that are strongly associated with type 2 diabetes.
• Addiction genes – these genes play an important role in addiction and normal eating behaviour. Significant variants in these genes may require you to use something like cognitive behavioural therapy alongside a dietary plan.

WHAT DOES THIS ALL MEAN?

An understanding of how your genes affect your environment and vice versa is the key to developing an effective weight management plan. Dieting should never be just about weight loss. It should always be about health. Nutrigenetic testing can be done through laboratories like DNAlysis. Personalised nutrition, with the help of a practitioner trained in Nutrigenomics, is the future for successful weight management.

We are all unique and respond differently to different food combinations. It’s time to find out which ones suit you.

Editor's note: Read my report on DNAlysis – The Genetic Testing Laboratory

References

1. The Heart and Stroke Foundation of South Africa. National obesity week: South Africa’s weighty problem.
2. Pienaar A. Prevalence of overweight and obesity among primary school children in a developing country: NW-CHILD longitudinal data of 6–9-yrold children in South Africa. BMC Obesity 2015; 2(2)
3. Masuo K et al. Rebound weight gain as associated with high plasma norepinephrine levels that are mediated through polymorphisms in the β2-adrenoceptor. Am J Hypertens 2005;18(11):1508–16.
4. Joffe Y, Houghton C. A novel approach to the nutrigenetics and nutrigenomics of obesity and weight management Current Oncology Reports 2016; 18:43.