First things first; the thrifty gene hypothesis is only one of the evolutionary explanations presented to justify the global epidemic of insulin resistance, obesity, and metabolic syndrome. It has major critics and multiple observations have failed to prove the idea. For example see:

Food and Western Disease; Health and Nutrition from an Evolutionary Perspective, Staffan Lindeberg, Wiley 2010

That being said, even if the thrifty hypothesis is correct then it takes millions of years until we can actually detect a big enough genetic shift in the human genome caused by the selection of Westerners over aboriginals. Hypothetically speaking, I think yes that would eventually happen.

There is an incorrect assumption in this question: We are already adapted to a high-fat, high-cholesterol diet. We have just come out of 2.5 million years of Ice Ages when, with long cold winters and short, cool summers, for most of the year there would have been very little plant material our ancestors could have eaten. For 2.5 million years, we ate animals or we starved. There is no doubt that this is the diet we must have adapted to. Although we have been eating increasing amounts of starchy foods for last few centuries, that is far to recent a change to have had a marked effect on our genetic make-up.

The question should be: Will we ever adapt to a carbohydrate-based diet? And I am not at all sure that we will. We are already beset with a whole raft of chronic degenerative diseases. If these make an appearance after our fertile and child-rearing years, there will be no effect, genetic or epigenetic, on the genes we pass to our offspring. And, as these diseases - including conditions such as falling sperm counts - are affecting younger and younger people, it is likely that they won't be such successful breeders.

Those are all good points but I am thinking about the premise on a molecular level compared to an anthropological one. I maintain that Westerner's have already successfully adapted to a "Western-Diet" (define it as you will). That is what obesity is. A successful adaptation to nutrient abundance. However, it seems that aboriginal populations are not able to adapt as well...why is this? It is because of gene variants? Same reason to as why Asian populations can not tolerate lactose and Europeans can. Europeans have a variant that allows them to digest lactose. So who is to say that Western-type societies have not already developed variants for dealing with nutrient abundance (albeit not well)? Westerner's develop pathologies due to their diet and lifestyle-there is no doubt but ,it seems as though the severity of those diseases can occur much more quickly and dramatically in other populations with the exact same lifestyle.

This of course is just supposition and conjecture. And I have being using the term "Westerner" as to identify any population that lives in a environment of nutrient abundance, while maintaining a sedentary lifestyle

Barry Groves who commented above is to my mind one of the smartest diet researchers of our time and in fact I have used one of his ideas, that most animals metabolize mainly fat for energy, in my last paper. However I must remark that human developed mainly in Africa and possibly in the Levant as well where the weather was not that cold. Still my research brought me to the conclusion that meat and fat composed most of our diet for most of the last 2 million years and as Dr. Grove found out in his research most mammals including our ancestors the Chimpanzee also metabolized mainly fat through bacteria aided fermentation of plant fiber that results in a by product of short chain saturated fatty acids which are absorbed by the gut.

It may take a long time if ever to adapt to a glucose dominated diet. No mammal that I know of is adapted to this kind of diet.

Elijah. Yours are also good points. I will concede that some peoples, with a longer history of living with unnatural foods such as milk and cereals, have started to develop the ability to tolerate them slightly better than others. But I would not concede that they are necessarily all that successful. I am surprised that you call obesity a successful adaptation to a Western diet. I would call obesity evidence of the harm that such a diet is doing because we are NOT adapted to it. We might not succumb to the 'diseases of civilisation' quite as quickly as do say, Pima Indians who have only a couple of hundred years' experience of our foods, but we do succumb.

However, those previous changes in our foods occurred over several millennia. Today, that relatively slow change of diet from meat-eating hunter/gatherer to cereal-eating city dweller has not only become much more rapid, our food has changed out of all recognition. Many of our civilisation no longer eat real food, but fake food. We are now clever enough to manufacture our own food out of non-food items (see the ingredients in fat-free sour cream, for example) and, unfortunately, many of us are stupid enough to eat it. As a consequence, the incidence of previously rare or non-existent diseases is rising with increasing rapidity. For example, when the AMA in the US and COMA in UK introduced us to the so-called 'healthy' diet in the 1980s, one person in six got cancer. That figure is now about one in two - and cancers are affecting ever younger people. I saw on the UK TV news only yesterday, the report of a baby of just 21 months with leukaemia! I seriously doubt that we can adapt to so rapid and large a change. Apart from needing a new set of enzymes, our whole physiology would need rearranging. That doesn't happen quickly.

I whole-heartily agree with your overall premise (I am being somewhat deliberately provocative) but I will maintain that obesity is, on the molecular level, a successful adaptation to nutrient abundance (even if it is for a short amount of time). Of course, like most things there are limits but I think that in most cases the pathologies that arises are a by-product of adaption. Cancer is an indiscriminate by product of aging. Would you say some is unsuccessful at aging if they have cancer?

Furthermore, there are successful and unsuccessful adaptions to prolonged starvation-why not obesity?

What makes the difference between successful and unsuccessful adaption in the case of starvation? Of course the environment itself plays a role but there must be something else, no? Genes. We can say that humans have had thousand of years to develop mechanisms that would allow them to adapt to starvation, while the same can't be said for diet-induced obesity, and I would completely agree. However, our cells are very good at dealing with excess nutrients to a point. We have several mechanisms that allow for this (i.e., ER stress, increased oxidation and of course storage-immediately come to mind) but they get overwhelmed easily. We just need to extend that tipping point.

We know there is potential to do so (both evolutionarily and pharmacologically), because through genetic manipulation, the ablation of certain genes results in a reduced risk of diet-induced obesity and the related disease that accompanies them. In most cases, what is a SNP if not a natural genetic manipulation? SNPs usually result in the up or down regulation of a gene or in most cases, a completely loss of function. Some favorable some not. Those that are favorable get selected for those that are not don't.

This is a really interesting discussion. If we classify obesity as an unsuccessful adaptation, we could look to normal weight as an indicator of successful adaptations to Western (high glucose) diet. Perhaps part of the successful adaptation is the behavioral response to nutrient abundance. Successful individuals may compensate with under-consumption. Would it be correct to hypothesize that among the normal-weight individuals, we can find a genetic associations with behavior?

Here are some references that may be of interest

"Subjects did not show a shift in either sweetened or unsweetened food choices while their diet was being diluted. In adjusting for the missing calories, they simply ate more of their customary diet)"

http://www.sciencedirect.com/science/article/pii/003193848290018X

"It is likely that a gene-environment interaction, in which genetically susceptible individuals respond to an environment with increased availability of palatable energy-dense foods and reduced opportunities for energy expenditure, contributes to the current high prevalence of obesity."

http://www.sciencedirect.com/science/article/pii/S0016508507005793

Miki.

Thank you for your kind words. I was intrigued by your mention of an article using one of my ideas. I assume it was' Man the Fat Hunter'. Your hypothesis is brilliant and I am sure you are right. Thank you for increasing my knowledge. Now we need to educate 'the-powers-that-be' in the nutritional world to the fact that, just like all other mammals, we are a fat-eating, not a carbohydrate-eating, species! And that it is their unsupported dogma which is having such disastrous effects across the industrialised world - and the developing world which we are influencing.

Marianna.

Looking at brain size across the millennia and its rate of shrinkage on plant-based diets, as well as the huge range of chronic, degenerative diseases which afflict only industrialised humans and the animals they control and feed, it is clear that a we will probably make ourselves so ill before we have much of a chance to adapt, that the question of whether we will ever adapt is moot.. That said, however, if any of our species did make such an adaption, I think it unlikely that we would have anything like the influence over other species that we have at present as our brains are already shrinking. And we would find ourselves no longer at the top of the food chain.

While building our brain to the size it is was before we adopted a more plant-based diet and agriculture, we had to sacrifice other energy-using organs - and that has meant we now have a very weak musculature compared to other wild animals. This fact could seriously hamper our survival in the natural world. In that world, all species increase to the limit of their food supply. At that stage it is a case of kill or be killed. I think we could well end as prey rather than the hunter we are now if we changed to and then managed to survive a herbivorous diet.

Barrry

Yes, it was Man the Fat Hunter. I felt uneasy about using your ideas as one (still) can't quote blogs in a scientific paper. Glad you liked our hypothesis.

I have at list two more papers in the making using the model built in the paper to implicate fat shortage in other events in human prehistory. Getting the animal fat phobia out of the system is doomed to be a long process thanks, partly, to the strong economical interest behind it. We can only do our best one step a a time.

You may want to take a look at my blog paleostyle.com

Miki

I like your blog.

A thought about the use of another's ideas: why not ask and, perhaps, list the artilcle's author as a co-author of your paper. That way all are satisfied and you wouldn't contravene the 'rules of evidence'.