If you are overweight or suffering from certain lifestyle diseases, it probably has to do with improper diet.
However, it appears there could be more to our health outcomes than just the food we consume.
One theory, called the mismatch hypothesis, suggests the problem is not really the type of food, and no diet is inherently harmful.
It argues that humans have evolved to digest the food of their ancestors and will struggle, and often fail, to metabolise radically new types of food, leading to problems such as lifestyle diseases.
The theory is difficult to test scientifically because it would mean going back to foods eaten hundreds of years ago for one community.
However, Kenyan scientists working alongside American researchers, have tested the theory in Turkana.
The scientists say the Turkana presented a perfect opportunity because many of them still practice nomadic pastoralism that their ancestors practiced for thousands of years and eat the same foods their ancestors ate.
Another group of Turkanas has migrated to urban areas and adopted a modern, carbohydrate heavy diet.
“The Turkana situation thus presents a unique opportunity, in that individuals of the same genetic background can be found across a substantial lifestyle gradient,” the scientists say in their study, published in the Science Advances journal.
They discovered that as the urban Turkana people adopted a new diet heavy on carbohydrates, there was an increase in obesity, diabetes and heart disease among them.
Traditional Turkana still rely on livestock for subsistence: 62 per cent of calories are derived from fresh or fermented milk, and another 12 per cent of calories come from animal meat, fat or blood.
The remaining calories are derived from wild foods or products obtained through occasional trade, according to the study.
Among the people who live such a lifestyle and eat the traditional diet, researchers found extremely low levels of cardiometabolic diseases.
“No individuals met the criteria for obesity or metabolic syndrome, and only 6.4 per cent of individuals had hypertension,” their paper says.
The scientists, drawn from Princeton University and Kenya-based Mpala Research Centre, interviewed 1,226 adult Turkana in 44 locations to get this data.
Julien Ayroles from Princeton explained that the experiment is not about favouring a protein-based diet.
He said if people with different ancestry switched to a Turkana diet, they would most likely get sick quickly.
Head of Mpala, Dino Martins, said this is the first genomics study they've conducted in Turkana.
“Doing research like this study involves a huge amount of trust and respect with our local communities and with more remote communities: how we access them, how we interact. And the reason Mpala and Turkana can be a hub for this is because we have a long-term relationship,” he said.
“The communities know us. We’ve been there for 25 years. Our research staff are drawn from local communities.”
