Question: Hi Dr Zac, My brother is falling down the rabbit hole of pseudoscience. This month’s conspiracy flavour is all about weight gain and its relationship to genetics.

He seems to think weight gain is connected to genetics, and that we should eat according to blood type.

It’s hard to convince him otherwise as he has lost a lot of weight recently, and he is saying it’s all because of the ‘alternative information’ he consumes.

Is this true? Am I not a shredded Instagram influencer because I’m eating the wrong foods according to my blood type? – Blade, 27, NSW

Answer: Great question Blade. Thanks to the pandemic and the surfacing of the anti-vaxxer community, we are all prone to slap unique ideas with the sticker of ‘pseudoscience’. I appreciate that you have reached out with your doubts, and I recommend following up this conversation with your GP if you continue to worry.

The blood type diet rose to popularity in the late 1990s after it was created by Dr. Peter D’Adamo. He wrote a book which outlined optimal diets for people according to their blood type. He linked it all to the genetic traits of our ancestors and what they thrived on.

According to Dr. D’Adamo, this is how each blood type is supposed to eat:

Type A: Called the agrarian, or cultivator. People who are type A should eat a diet rich in plants, and completely free of “toxic” red meat. This closely resembles a vegetarian diet.

Type B: Called the nomad. These people can eat plants and most meats (except chicken and pork), and can also eat some dairy. However, they should avoid wheat, corn, lentils, tomatoes and a few other foods.

Type AB: Called the enigma. Described as a mix between types A and B. Foods to eat include seafood, tofu, dairy, beans and grains. They should avoid kidney beans, corn, beef and chicken.

Type O: Called the hunter. This is a high-protein diet based largely on meat, fish, poultry, certain fruits and vegetables, but limited in grains, legumes and dairy. It closely resembles the paleo diet.

I’d just like to point out to everyone that following any of these dietary patterns would likely see an improvement in most people regardless of their blood type.

I would say the theory is interesting and warrants further conversation and investigation.

I am more and more amazed at how quickly science and technology are progressing which in turn means health and medicine. We’re still at the tip of the iceberg when it comes to learning everything there is about our own health and wellbeing.

Herbs, naturopathy, ancient wisdom, healthy produce, better agriculture, culturally diverse practices and so much of what ‘western medicine’ utilises today we are only just now proving to work. For example, the same medication or ingredient can smell delicious for one person but not another, why some people get restless and agitated, upset stomach or anaphylaxis and others feel nothing or the opposite.

I have long said that I studied biochemistry before medicine to find out how things work. Medicine of the future will continue to look at alternative medicine practices, ancient techniques, ingredients and advice that seems sound and be able to prove it. We will be able to tell you how and why it works. As the comedian Tim Minchin wonderfully quipped “What do you call alternative medicine that actually works? Medicine.”

It’s very misleading to use the words, genetics and blood type, as the sole foundations of weight loss and diet advice. We are complex organisms for which we are discovering new things daily. At this stage probably 10 per cent of the risk linked to obesity and type-2 diabetes can be explained by genes directly and the rest will be how the environment influences our cells. I do not recommend following the theory that all things weight and obesity are linked to genetics.

We often get confused and muddled from alternative theories and fat diets when really healthy weight loss is so simple. It can be simple as basic healthy living – sleeping well, eating well and exercising well.

Got a question: askdrzac@conciergedoctors.com.au

Dr Zac Turner has a Bachelor of Medicine and Bachelor of Surgery from the University of Sydney. He is both a medical practitioner and a co-owner of telehealth service, Concierge Doctors. He was also a registered nurse and is also a qualified and experienced biomedical scientist along with being a PhD Candidate in Biomedical Engineering