I came across this study a bit ago and it caught my eye as I was transfering some stuff between computers: Marked Improvement in Carbohydrate and Lipid Metabolism in Diabetic Australian Aborigines After Temporary Reversion to Traditional Lifestyle
The rationale for the present study was that temporarily reversing the urbanization process in diabetic Aborigines should improve all aspects of their carbohydrate and lipid metabolism that are linked to insulin resistance. Ten full-blood, diabetic Aborigines from the Mowanjum Community (Derby, Western Australia) agreed to be tested before and after living for 7 wk as hunter-gatherers in their traditional country in northwestern Australia. They were middle aged (53.9 ±1.8 yr) and overweight (81.9 ± 3.4 kg), and all lost weight steadily over the 7-wk period (average, 8 kg). A detailed analysis of food intake over 2 wk revealed a low energy intake (1200 kcal/person/day). Despite the high contribution of animal food to the total energy intake (64%), the diet was low in total fat (13%) due to the very low fat content of wild animals.
... In conclusion, the major metabolic abnormalities of type II diabetes were either greatly improved or completely normalized in this group of Aborigines by relatively short reversal of the urbanization process. At least three factors known to improve insulin sensitivity (weight loss, low-fat diet, and increased physical activity) were operating in this study and would have contributed to the metabolic changes observed.
They worked with a bunch of middle aged, overweight, urbanized Australians of Aboriginal descent ... eating the "SAD" (A=Australian) circa early 1980's. That failed low fat diet? Not quite:
Urban diet: The main dietary components were flour, sugar, rice, carbonated drinks, alcoholic beverages (beer and port), powdered milk, cheap fatty meat, potatoes, onions, and variable contributions of other fresh fruit and vegetables. At the time of the study the composition of the diet was estimated to be: carbohydrate 50%, fat 40%, and protein 10%. There was considerable variation within the group depending on the contribution of alcohol to the diet. The nondrinkers were more concerned about their diet in the urban environment and tended to eat more fresh fruit and vegetables and wholemeal bread.
Below is the summary of the study and general diets:
After initial evaluation, they traveled to remote areas where the participants were cut-off from modern sources of food (e.g. supermarkets).
During the 10-day trip from Derby to the coastal location, the diet was mixed and included locally killed beef, since supplies of bush food were inadequate: meat (beef, kangaroo), fresh-water fish and turtle, vegetables, and honey. It was estimated that beef comprised 75% of the energy intake during this 10-day period ... No further beef was consumed once the group arrived at the coastal location. During the 2-wk period spent on the coast, the diet was derived predominantly from seafood with supplements of birds and kangaroo. The lack of vegetable food in this area eventually precipitated the move inland to the now-abandoned site of the old homestead. ... At the inland location, which was on a river, the diet was much more varied: kangaroo, fresh-water fish and shellfish, turtle, crocodile, birds, yams, figs, and bush honey.
Ahh! So they ate a majority animal-based diet that was LCHF. .... Not so fast. It was indeed extremely low carb at the coastal area -- which fact caused them to move inland for plants! But it turns out that wild animals are not particularly fatty ... go figure! The coastal diet was only estimated to be 20% fat ... look at that protein -- 80%!!! Oh the rabbit starvation! But they couldn't assuage that with more fat, they had to find some carbs, at which point fat intake was measured to dip below the 15% mark -- THIRTEEN PERCENT FAT! In this phase protein made up for 50% of calories. How can that be? Well, not hunting and gathering at Whole Foods may have had something to do with the fact that they averaged only 1200 calories per day. Not a typo. For the coastal diet, protein intake would have averaged around 240g/day while the more moderate inland diet was roughly 150g/day. But not only were these diets low fat by percent, they were super low fat by absolute content, only 17 to 27g! Even the 10 traveling days of "high fat" at 40% only amounted to 54g/day.
So I highlighted it twice -- these low carb diets were not high fat.
Here's what happened, in addition to an average of 8kg weight loss:
The major finding in this study was the marked improvement in glucose tolerance in 10 diabetic Aborigines after a 7-wk reversion to traditional hunter-gatherer lifestyle. There were two components to this improvement: a striking fall in the basal (fasting) glucose concentration and a less marked, but nevertheless significant, improvement in glucose removal after oral glucose. Associated with the improvement in basal glucose metabolism was a significant fall in the fasting insulin concentration in the diabetic subjects. Although peak postprandial insulin concentrations were no different before and after the temporary lifestyle change, the fall in fasting insulin concentrations indicated that the actual insulin response to oral glucose had increased in these diabetic subjects. This increased response occurred despite the markedly reduced glycemic stimulus.
These are summarized in the figures below.
The right side figures are incremental insulin (top) and glucose (bottom) that demonstrate that the acute insulin response is notably improved in these diabetics. still not a normal response, but bottom left is a marked improvement in both fasting glucose and glucose levels with a 75g OGTT.
What is responsible for this? I think it's a combination of increased activity and caloric restriction (due to lesser food availability). As demonstrated in the LoBAG diet studies (blogged on here), I think the high protein content has a beneficial effect via IGF-1. Although the LoBAG diets are higher in fat, perhaps the low fat content of the hypocaloric diets helped to reduce pancreatic fat content as in "crash diet" studies (such as blogged on here and here). The combination seems to have been beneficial. Yes, carb intake was lowered as well, but the results here are such that they are clearly able to "tolerate" a glucose load better after the intervention. This reminds me of the Inuit study (help me out I can't find it :( ) where they consume roughly 45% protein in their traditional diet and exhibit excellent glucose tolerance despite consuming essentially zero carb (in that culture/study).
But to my title, forget PrimalCon ... the next big thing will be medical vacations mimicking this study!