Might we study one thing from the dietary habits of squirrels, significantly their penchant for acorns, which they rely on to fatten up for the winter? In line with Brad Marshall, a molecular biologist, farmer and chef, the key to staying slim could lie within the historical relationship between squirrels and the oak bushes that give them their favourite meals supply.
“All mammals advanced from a standard ancestor. We have now the identical enzyme methods that management vitality stability out and in and regardless that we reside in several environments and we now have completely different most popular meals, our metabolisms all primarily work the identical means,” Marshall says.1
Oak Bushes Make Acorns to Fatten Up Squirrels
You might assume that squirrels advanced to eat acorns with a view to achieve weight earlier than winter units in. However Marshall factors out that mammals have been round for at the least 200 million years, whereas flowering vegetation like oak bushes and hickory bushes are comparatively a lot youthful, evolving round 130 million years in the past.
“I imagine that the bushes advanced to make use of mammals to maneuver their seeds round for them,” Marshall says.2 He cites a examine of untamed pink squirrels,3 which discovered their physique weight elevated from about 310 grams to 330 grams within the fall once they eat essentially the most acorns.
“They’re primarily including about 10% of their weight in physique fats in the course of the a part of the yr once they’re consuming these acorns and, after all, from the attitude of the tree, the tree wants these squirrels to fatten up. The tree wants a wholesome squirrel inhabitants in order that it will probably unfold its seeds and so that is what squirrels eat.”4
Within the fall, acorns and hickory nuts make up 90% of squirrels’ diets. This falls to about 50% to 63% in the summertime, when squirrels are their leanest. Marshall poses the query:
“So … in case you are an oak tree and it is your crucial to fatten up your squirrels in order that they’ll survive winter as a way to unfold your seeds, what do you make your acorns out of?”5
Black oak acorns, which squirrels choose, include about 46% of energy from fats, 48% of energy from carbohydrates and 6.6% of energy from protein. “That’s the equation that the oak bushes determined to make use of.”6
The acorns, together with hickories and chestnuts, are very low in saturated fats with very excessive quantities of monounsaturated fats and “fairly a little bit of polyunsaturated fats together with starch within the acorns. That appears to be the recipe that’s most popular,” Marshall factors out.7 Within the video, he then reveals knowledge exhibiting folks in France, who eat extra butter and dairy fats, are leaner than these in Italy and Spain, the place olive oil is favored.8
Why Acorns Make Squirrels Fats
A squirrel digesting an acorn can educate us rather a lot about fats digestion and its results on the physique. When a squirrel eats an acorn, its physique breaks down the fat it accommodates. Throughout this course of, the squirrel’s intestines launch a substance known as oleoylethanolamide (OEA). OEA acts as a sign telling the physique that fat are being digested.
As soon as OEA enters the bloodstream, it triggers a response within the liver by activating a receptor often known as PPAR-alpha. This activation begins the method of fats accumulation within the physique. Researchers examine this course of through the use of particular mice fashions known as “knockout fashions,” the place particular genes are eliminated to see the consequences.
In research centered on diet-induced weight problems, these mice are fed a food regimen just like the composition of acorns, which is excessive in fats, primarily from lard and a few soybean oil.
This food regimen mirrors the fatty content material of acorns and is designed to induce weight problems and insulin resistance in mice. An vital level is that lard is especially composed of monounsaturated fat (MUFAs); fashionable lard accommodates extra polyunsaturated fat (PUFAs) than it used to. The food regimen for the mice contains about 5% soybean oil to make sure there’s sufficient PUFA.
This food regimen successfully causes weight achieve and insulin resistance in mice. The research present that having the PPAR-alpha receptor is essential for the mice to develop insulin resistance, providing insights into how fat have an effect on the physique’s metabolic processes.
An identical course of happens in people once they’re given a drug known as fenofibrate, which additionally prompts PPAR-alpha. In a examine carried out on males, researchers used fenofibrate to deliberately activate PPAR-alpha to check its results on the liver.9
Curiously, Marshall explains, whereas fenofibrate is efficient at reducing ldl cholesterol, this was the primary time researchers immediately noticed its influence on the liver in people. The outcomes confirmed that fenofibrate elevated liver fats content material by about 23%, which means that activating PPAR-alpha can have unintended results on the physique’s fats storage processes.
Moreover, the examine examined the exercise of two enzymes: delta-6 desaturase and delta-9 desaturase, often known as SCD-1. These enzymes play roles in fats metabolism, and their exercise ranges elevated considerably — by about 58% and 36%, respectively — in members whose PPAR-alpha was activated by fenofibrate. This enhance in enzyme exercise additional signifies modifications in how the physique processes and shops fat.10
The importance of those findings lies within the connection to MUFA, like these present in acorns. The presence of MUFA can provoke the activation of PPAR-alpha, showcasing its function as a key regulator in fats metabolism.
What This Means for Human Metabolism
When glucose from meals like acorns enters a cell, it undergoes a course of known as glycolysis within the cell’s cytoplasm, changing into pyruvate. This pyruvate then strikes into the mitochondria, the cell’s powerhouse, the place it has two major pathways. One pathway includes conversion into acetyl coenzyme A (acetyl-CoA) by an enzyme known as pyruvate dehydrogenase, resulting in the tricarboxylic acid (TCA) cycle, a crucial step in vitality manufacturing from meals.11
Throughout this cycle, acetyl-CoA is damaged down, producing molecules known as nicotinamide adenine dinucleotide, or NADH. The supply of one other molecule, NAD+, is essential right here as a result of a scarcity can decelerate metabolism. Your physique has mechanisms to transform NADH again to NAD+ to take care of metabolic stability.
One major technique is thru the electron transport chain within the mitochondria, which not solely regenerates NAD+ but in addition produces ATP, the vitality forex of the cell used for all the pieces from shifting muscle groups to mind features.
Nonetheless, not all vitality manufacturing goes easily. When there’s an extra of NADH and never sufficient demand for ATP, an enzyme known as pyruvate dehydrogenase can change into much less energetic, resulting in the manufacturing of reactive oxygen species (ROS), like hydrogen peroxide. One other enzyme, NNT, helps convert this probably dangerous byproduct again into water, concurrently changing NADH again to NAD+.
However, when PPAR-alpha, activated by the MUFAs from acorns, comes into play, it inhibits pyruvate dehydrogenase by activating a distinct enzyme, pyruvate dehydrogenase kinase. This motion prevents the traditional breakdown of pyruvate by way of the TCA cycle. As a substitute, pyruvate takes an alternate route by way of an enzyme known as pyruvate carboxylase, favoring the manufacturing of a compound known as oxaloacetate.
This shift redirects the cell’s vitality processes, combining pyruvate from carbohydrates and acetyl-CoA from fat to create new fat by way of a course of known as de novo lipogenesis. Primarily, Marshall explains, the presence of PPAR-alpha, stimulated by fat within the food regimen, influences your physique’s determination to transform carbohydrates into fats.
Why Diets Excessive in Linoleic Acid Are Fattening
Acorns from pink or black oaks are a mixture of fat and carbohydrates, with their fats content material being principally monounsaturated and a very good portion of it being linoleic acid (LA), a PUFA.
LA accounts for about 80% of the fats composition of vegetable/seed oils. Examples of seed oils excessive in omega-6 LA embrace soybean, cottonseed, sunflower, rapeseed (canola), corn and safflower.12
Marshall explains that the presence of oleic acid, one other part of the fats in acorns, can also be vital as a result of it triggers a response within the liver that prompts PPAR-alpha. As soon as activated, PPAR-alpha influences how the cell makes use of vitality, resulting in a desire for creating new fat relatively than simply burning carbohydrates for vitality.13
This course of includes a number of steps inside the cell. Excessive ranges of NADH, which happen when PPAR-alpha is energetic, favor the conversion of gear within the cell in a means that results in fats manufacturing. Particularly, delta-6 desaturase converts LA to arachidonic acid, which performs a job in creating molecules that may set off reactions resulting in the manufacturing of gear related to weight problems.
The activation of PPAR-alpha and one other part known as cytochrome P450 1B1 additionally results in elevated exercise of an enzyme known as SCD1. This enzyme, together with others concerned in fats creation, ramps up your physique’s capability to make fats.
In consequence, sure fatty acid ranges change, selling the storage of fats over burning it for vitality. This mechanism slows down the metabolic fee, inflicting your physique to retailer extra energy as fats.
From the attitude of an oak tree, this course of is good, Marshall says. By producing acorns that result in the storage of fats, oak bushes assist squirrels achieve the load essential to survive the winter. This ensures the squirrels are able to disperse the oak’s seeds, serving to within the tree’s replica.
This intricate connection between the composition of acorns and the metabolic processes in animals that eat them illustrates a captivating facet of pure symbiosis that additionally provides clues to human weight problems.
Briefly, Marshall notes, “Black and pink oak acorns have advanced to be completely fattening,”14 and so, too, have the modern-day diets that mimic them, that are very low in saturated fats with very excessive quantities of MUFA, and PUFA like LA.15 Ideally, your consumption of LA must be under 5 grams a day.
The simplest means to do that is to make use of a web-based dietary calculator similar to Cronometer to calculate your each day consumption. Cronometer will let you know how a lot omega-6 you’re getting out of your meals all the way down to the tenth of a gram, and you’ll assume 90% of that’s LA. Something over 10 grams is prone to trigger issues however, as talked about, I like to recommend holding your consumption under 5 grams a day.
