• “You can’t impose a set of dietary values, like keto, on a worldwide population and think that every single human being is going to react in the same way.” (Getty Images)Source: Getty Images
There’s a very valid reason why you should never compare your dieting success to anyone else's: genetics.
By
Yasmin Noone

12 Aug 2020 - 12:03 PM  UPDATED 12 Aug 2020 - 12:04 PM

If you’ve ever tried a trending diet, like ketogenic or paleo, and not had much luck achieving weight loss or health success, fear not.

According to Amanda Archibald, a culinary genomics expert, the reason might be in your genes.

The US dietitian tells SBS your dietary success may depend on your genetic makeup, which is also influenced by your culture.

So if you’re not losing as much weight as the next person on a trending diet, or your health declines because of the same dietary change that helped another person improve theirs, it might all come down to your DNA.

“We are all unique so we each have our own DNA blueprint because that’s how we are built,” says Archibald.

“But the great thing about your genes is that they never lie. They care about your culture but they don’t care what anyone has to say [about the success of a trending diet]. They basically reflect who you are and so they are the best source of information for you to direct your health.”

“But the great thing about your genes is that they never lie. They care about your culture but they don’t care what anyone has to say [about the success of a trending diet]."

To explain the complicated field of genomics further, Archibald advises people to think of their genes as a set of culturally diverse traffic lights.

“They determine how traffic moves around your body. Your paleo or keto traffic works differently to how my traffic moves around. Mine might get clogged up while yours may work fine.”

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Archibald focuses on the ketogenic diet: a diet that is very low in carbohydrates and high in fat. The ‘keto’ diet aims to help you lose weight by inducing a metabolic state called ketosis, which forces the body to burn fat.

She says that although the keto diet may work for some people in the short-term, it may not operate the same way in everyone.

“On the outside, two people can both rapidly lose weight but when you do a blood test and grab information from the lab about their health on the inside, you can see significant differences between [the health] of people all on the same kind of diet. That’s where you see genetics coming in.”

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Archibald states that you can have errors on your genes that determine how well you package fat or utilise fat.

“Let’s say two people lose 10 kilos,” she says. “But one person’s lab information may show that their triglycerides or LDL cholesterol is through the roof. Even though they are on a diet, they might be thin on the outside and fat on the inside - or potentially dying on the inside.

“That’s because their genes determine how their body will use dietary information [and respond to a diet]. That’s why the keto diet is not for everyone by any means.”

"Even though they are on a diet, they might be thin on the outside and fat on the inside - or potentially dying on the inside."

A ketogenic diet is not recommended for people with kidney issues or people in a high-risk group of kidney disease. This includes individuals from cultural groups with a genetic predisposition to kidney diseases such as Aboriginal and Torres Strait Islander peoples.

Individuals living with diabetes are also advised to manage their condition by following a diet lower in fat, particularly saturated fat. So the keto diet, which is high in fat, would not work for them. Diabetes Australia has also urged Australians to recognise that one diet does not fit all.

A study published in the journal, Genetics in 2018, looked at how genetic differences influence the way we may respond to popular diets.

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Researchers designed human-comparable mouse diets based on the American/Western diet that was high in fats and refined carbs, Mediterranean diet, Japanese and ketogenic diet.

The results showed that the health effects of the diets were highly dependent on genetic background.

The three healthier diets worked for most mice but a fourth genetic strain did not respond well to the Japanese diet, experiencing increased fat in the liver and liver damage.

Two genetic strains responded well to the keto diet although two responded badly, developing a fatty liver and high cholesterol.

“If similar genetic-dependent diet responses exist in humans, then a personalised, or ‘precision dietetics,’ approach to dietary recommendations may yield better health outcomes than the traditional one-size-fits-all approach,” the study led by William Barrington reads.

“You can’t impose a set of dietary values, like keto, on a worldwide population and think that every single human being is going to react in the same way.”

Although blaming your genes for a dietary failure may sound like scapegoating, Archibald insists that understanding our basic genetic differences can help people eventually find a diet that is right for them.

“You can’t impose a set of dietary values, like keto, on a worldwide population and think that every single human being is going to react in the same way,” Archibald says. “They don’t and they can't because their genes and [people in] their culture have never eaten that way in thousands of years.”

However, she stresses that people need not rush out and buy expensive genetic tests to find out more information about their DNA. Instead, she says, eat a healthy diet based on basic nutritional principles. Also, be kind to yourself if the hard work you put into a diet doesn’t pay off as you thought it would.

“When we unfold that book of genomics, it tells a story of someone’s life and health and it gives them freedom to say ‘I wasn’t imagining the fact that this diet wasn’t working for me.’ And that statement is very powerful.”

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