Big Brains, Diabetes, and the Role of Fasting

It appears that dolphins have the ability to regulate their “fasting gene” in order to prevent type 2 diabetes. In other words, they can oscillate between lengthy periods of either continuous eating or fasting without compromising blood glucose levels necessary to sustain optimal health and energy levels.

This does not, however, appear to be a trait that dolphins share with other large marine mammals such as seals and walruses. And the likely explanation is that dolphins, with their much larger brains, require higher levels of blood glucose to fuel their high-energy brain tissue – just like humans.

So why are dolphins unique in this ability when compared to their more cerebrally-challenged counter parts? Per the researchers:

Dr Venn-Watson explained that the mammals may have evolved this fasting-feeding switch to cope with a high-protein, low-carbohydrate diet of fish. “Bottlenose dolphins have large brains that need sugar,” Dr Venn-Watson explained. Since their diet is very low in sugar, “it works to their advantage to have a condition that keeps blood sugar in the body… to keep the brain well fed”.

Although these findings are preliminary, there may very well be similarities in how dolphins and other big-brained species – namely humans – regulate insulin and glucose at a genetic level.

This makes sense from an evolutionary standpoint. High carbohydrate foods were conspicuously absent from the human diet until the advent of agriculture. And grain-based carbohydrates such as wheat, barley, rice, and maize (corn) became staples in our diet only about 5,000 – 8,000 years ago. Prior to that, the human diet consisted largely of proteins and fats (both animal and plant source) with carbohydrates coming less frequently from plant-based sources.

Given this history of high-protein, low-carbohydrate food consumption, it makes sense that humans would have evolved to develop a similar “fasting gene” that could switch on and off to maintain brain energy levels during times of scarcity.

Again, the findings of this study are subject to further examination. But it appears that the “dolphin model” might actually be more applicable to us humans than we realize:

And we have found changes in dolphins that suggest that [this insulin resistance] could get pushed into a disease state. If we started feeding dolphins Twinkies, they would have diabetes.