What would happen to carbohydrate and lipid metabolism if a group of overweight Aboriginal people with type 2 diabetes living a typical urban lifestyle reverted to their traditional lifestyle?
In 1984 nutrition scientist Professor Kerin O’Dea carried out this novel research on the beneficial health impacts of temporary reversion to traditional hunter-gatherer lifestyle(1). She accompanied these Aboriginal people into the outback for field measurements and observation of their lifestyle.
The study cohort
Despite the high percentage of animal food (64%) the diet was low in total fat due to the low-fat content of wild animals
Ten diabetic Aboriginal people from the Mowanjum Community (Derby, Western Australia) agreed to be tested before and after living for seven weeks as hunter gatherers in their traditional country. They were middle aged and overweight and all lost weight over the seven-week period (average 8kg). They spent two weeks on the coast and three weeks inland.
The diet contained 1200 calories per day of which 54% was protein, 33% carbohydrate and 13% fat. Despite the high percentage of animal food (64%) the diet was low in total fat due to the low-fat content of wild animals.
Oral glucose tolerance tests (75g glucose) were conducted in the urban setting and repeated at the end of the 7 weeks of traditional lifestyle. There was a fall in fasting glucose (11.6 +/- 1.2mM before, 6.6 +/- 0.8 mM after) and an improvement of postprandial glucose clearance. Fasting plasma insulin concentration fell and the insulin response to glucose improved.
The was a marked fall in fasting plasma triglycerides (4.0 +/- 0.5 mM before, 1.2mM +/- 0.1 mM after). The omega 6 (n-6)/omega 3 (n-3) ratio in this traditional diet was approximately 1 (whereas the ratio for the American diet is now about 20 and the Australian diet about 10). This changing trend with modern diets was due to both the advent of the modern vegetable oil industry and the increased use of cereal grains as feed for domestic livestock (which in turn altered the fatty acid profile of meat that humans consumed).
What was consumed?
So, what were the changes observed amongst the participants reverting to a traditional lifestyle? There was a wide range of wild animals and plants eaten. To gather these lots of walking was needed. Also, there was energy consumed chopping, winnowing and grinding seeds, digging pits for baking and gathering wood for fire etc. Plant foods were yams, seeds and wild plums. Witchetty grubs (the larval stage caterpillar of a large cossid wood moth) were also eaten. Animal food comprised kangaroo, goanna, snake, emu, turtle and seafood. The study participants tended to eat every part of the animal including offal.
Even the lean meat of introduced animals like wild rabbits and cats was eaten. Kangaroo is rich in long chain fatty acids and has negligible fat in the muscle (marbling) compared with say wagyu beef, which is very high in saturated fat.
Relevance for us all
So, what can we learn from these findings to encourage healthier food consumption?
One piece of advice would be to rely more on natural plant food containing slower to digest carbohydrate. When eating meat, choose leaner cuts and remove the fat. Kangaroo meat is inexpensive and leaner compared with beef or lamb.
Perhaps most of all we could through education better understand and build respect for the pre-colonial settlement Aboriginal culture, land management and lifestyle. Their knowledge of land care with the help of planned and controlled fire stick agriculture for germinating seeds, extending savannah grasslands, processing nuts and yams, ambushing animals etc is a topic worth learning about as an important part of Australia’s past social history.
Recommended is Bruce Pascoe’s book Dark Emu(2) and Bill Gammage’s book The Biggest Estate on Earth(3). Both publications open one’s eyes to a very sophisticated land management system creating the best possible conditions for food production which sustained a civilisation in a largely arid land over 60,000 years. A significant amount of research for these books came from the reported observations of our early explorers and settlers.
(1) Diabetes. 1984 Jun, 33(6) 596-603
(2) Dark Emu, Bruce Pascoe: 2014 Griffin Press
(3) The Biggest Estate on Earth, Bill Gammage: 2012 Allen and Unwin