“Insulin is vital for lipogenesis. Its role equally a lipogenic hormone is underplayed, but nosotros know that without insulin, yous can’t instruct fat.”
--Dr. Roger Unger
Having raved almost the previous insulin post, obviously, I think he’s pretty brilliant. That beingness said, chronically elevated insulin isn’t the only machinery yesteryear which people accumulate excess adipose tissue. (For the newbies out there, “accumulating excess adipose tissue” is the fancy way to tell “get fat.”) I prefer to usage the give-and-take adipose instead of fat, because I am trying to brand a distinction betwixt dietary obese that nosotros eat inwards food, in addition to the body obese that nosotros all dear to loathe hence much on our bellies, hips, thighs, in addition to elsewhere. Even if they both occur inwards the cast of triglycerides, I all the same desire to locomote along them separate, since eating dietary obese does non automatically termination inwards said obese depositing itself on our nurture ends or forming mo in addition to 3rd chins.
Apart from insulin, at that spot are several other things that contribute to the rule of trunk weight, and, possibly to a greater extent than important, the composition of that weight. And I’m non ignoring those. Sometime inwards the side yesteryear side few weeks, I’ll hold upwards writing a postal service almost the myriad other reasons person powerfulness non hold upwards losing weight on a low-carb diet (unrelated to this insulin series). For our purposes right now, though, we’ll stick amongst insulin. Because fifty-fifty if at that spot are other factors playing a role inwards excess adiposity, when nosotros hold back at changes that receive got occurred to the nutrient provide in addition to the full general dietary guidelines from diverse regime in addition to professional person medical/health organizations during the final several decades, systemic hyperinsulinemia is likely 1 of the largest influences, if non the unmarried largest.
In tackling the role of insulin on the accumulation of adipose tissue, commencement nosotros request to explore but a few to a greater extent than things almost insulin’s biochemical & physiological roles. After that, we’ll run into how it all plays out inwards the existent world—that is, inwards the body.
Last time, I wrote, “There’s no dubiousness insulin does receive got an of import role inwards regulating—or, to a greater extent than specifically, lowering—blood glucose (BG). But that’s non insulin’s only function. In fact, I would debate it’s non fifty-fifty the primary function.” But fifty-fifty if lowering BG is the main component division of insulin, hence the method yesteryear which this is accomplished sheds a lot of low-cal on what insulin does in addition to explains the rest of insulin’s effects to a greater extent than satisfactorily. Time to revisit the hormone nautical chart from final time, but amongst a focus on unlike things:
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| Chart courtesy of Charles Saladino, PhD, Misericordia University |
Do yous yell back that vocal from Sesame Street? “One of these things is non similar the others…” Well, 3 of these hormones—glucagon, epinephrine, in addition to cortisol—all “stimulate obese acid release from adipose tissue.” You know what that means, right? That’s lipolysis—the breaking downwards of fat—stored trunk fat! But directly hold back at insulin. It is the alone one—the alone one—of these 4 hormones that “stimulates obese acid synthesis & storage afterward a high-carbohydrate meal.” And yous know what that means, right? The storing of obese on the body. Indeed, THIS may hold upwards the primary role of insulin: inhibition of lipolysis. (Or, anti-catabolism, inwards full general -- the edifice up, rather than the breaking down, of tissue.)
We know 1 of insulin’s functions is to stimulate the glucose-lowering cascade. What else does insulin do? Well, whereas cortisol, epinephrine, in addition to glucagon are catabolic, insulin is anabolic. The commencement 3 intermission things down; insulin builds things up. What does it construct up? At the real least, it stimulates the buildup of glycogen; the synthesis of structural & skeletal protein; in addition to the synthesis of obese acids via the conversion of glucose into triglycerides. (Again, nerd that I am, I am beingness real careful amongst how I give-and-take things. See, insulin is a hormone, non an enzyme. Again, equally a hormone, it’s to a greater extent than of a signaling agent than something that genuinely does anything, itself. Insulin stimulates or inhibits diverse biochemical processes yesteryear affecting enzymes, which are what genuinely participate inwards the moving & shaking that goes on at the cellular level. I am non ever hence careful amongst my phrasing, hence I’m but putting this out at that spot hence you’ll know how these things work, fifty-fifty when I instruct linguistically lazy. It would hold upwards less-than-correct to tell that insulin, itself, does x, y, in addition to z. It’s to a greater extent than similar insulin tells other players what to do.)
Evolutionary Biology:
A Clash Between Our Genes in addition to our Jeans
We tin seat this inwards perspective yesteryear looking at it through our ancestral/evolutionary wellness framework: If yous were consuming lots of fruit inwards summertime, in addition to plenty of mash in addition to starchy tubers throughout autumn, your overall insulin levels powerfulness receive got been higher than at other times of year. But this would receive got served a expert purpose, right? The biochemical betoken of elevated insulin tells the trunk to shop fuel. The storage of fuel (in the cast of adipose tissue) would receive got been a crucial survival machinery to instruct yous through the long winter, when nutrient was presumably less abundant. The trunk would run into frequent in addition to large-ish insulin spikes inwards summertime in addition to autumn equally a good thing. You would want to inhibit lipolysis for most of summertime in addition to fall. If yous were breaking downwards a bunch of your adipose tissue during those seasons, yous would hold upwards inwards deep trouble come upwards the food-scarce winter. This is a perfectly expert protective in addition to survival mechanism. The occupation now, equally most of us recognize, is that inwards the modern industrialized world, the metaphorical wintertime never comes, but our diets in addition to lifestyles all the same promote storage, storage, storage. (We volition hold back at roughly other way the accumulation of adipose is a protective machinery inwards a time to come post. Just locomote along this overarching topic inwards mind: the trunk tends to create whatever it tin inwards fellowship to remain alive, all the way downwards to the cellular level. Seen this way, many of our modern ills in addition to “diseases” are quite elegant, biochemically speaking, fifty-fifty land they wreak fatal havoc at the marker of the whole organism. I addressed this in my cancer series, when I explained that cancerous changes at the cellular marker tin hold upwards interpreted equally a survival mechanism on the component division of the cells.)
Back to the hormone chart: As yous tin see, at that spot are 3 hormones that are catabolic. That is, they break tissue down, to a greater extent than oftentimes than non inwards reply to falling blood sugar. In fellowship to locomote along blood refined saccharify high enough to create whatever the trunk needs to do—run from a tiger? Fight off a bear?—glucagon, epinephrine, in addition to cortisol all stimulate gluconeogenesis and/or glycogenolysis. Meaning, they stimulate the breakdown of glycogen into private glucose molecules, and/or they stimulate the catabolism of musculus tissue, inwards fellowship to liberate amino acids that tin hold upwards converted into glucose. They also stimulate the catabolism of adipose tissue, which releases obese acids that tin hold upwards used equally fuel, equally good equally the glycerol part of the stored triglycerides, which tin hold upwards converted into glucose.
So nosotros know insulin lowers blood glucose, right? How insulin does this is roughly other story. Insulin doesn’t genuinely escort glucose out of the bloodstream in addition to into cells. What insulin does is human activity to a greater extent than similar a signaling agent: insulin binds to a receptor on the surface of the jail mobile telephone membrane, in addition to inwards reply to the binding of insulin, glucose transporters (GLUTs) are moved (or “translocated”) from within the jail mobile telephone to bridge the jail mobile telephone membrane. It’s the GLUTs that genuinely suck the glucose into the cell. And, but hence nosotros know the total story here, some GLUTs require insulin to stimulate their translocation; others don’t. So insulin is non the only way glucose tin instruct into cells. (As I mentioned final time, physical activity is a corking way to get “non-insulin mediated glucose uptake.”)
Insulin: Miracle-Gro for Adipose Tissue
We know 1 of insulin’s functions is to stimulate the glucose-lowering cascade. What else does insulin do? Well, whereas cortisol, epinephrine, in addition to glucagon are catabolic, insulin is anabolic. The commencement 3 intermission things down; insulin builds things up. What does it construct up? At the real least, it stimulates the buildup of glycogen; the synthesis of structural & skeletal protein; in addition to the synthesis of obese acids via the conversion of glucose into triglycerides. (Again, nerd that I am, I am beingness real careful amongst how I give-and-take things. See, insulin is a hormone, non an enzyme. Again, equally a hormone, it’s to a greater extent than of a signaling agent than something that genuinely does anything, itself. Insulin stimulates or inhibits diverse biochemical processes yesteryear affecting enzymes, which are what genuinely participate inwards the moving & shaking that goes on at the cellular level. I am non ever hence careful amongst my phrasing, hence I’m but putting this out at that spot hence you’ll know how these things work, fifty-fifty when I instruct linguistically lazy. It would hold upwards less-than-correct to tell that insulin, itself, does x, y, in addition to z. It’s to a greater extent than similar insulin tells other players what to do.)
Two of the enzymes insulin affects are hormone sensitive lipase in addition to lipoprotein lipase. (I talked briefly almost this way dorsum in the fuel partitioning series. In fact, that postal service is likely the CliffsNotes version of this one, hence if you’re pressed for time, but become read that instead.) As I wrote there: “We request alone to hold back at untreated type-1 diabetics to empathise that (barring whatever other wacky hormonal complication) it is darn close impossible to accumulate trunk obese inwards the absence of insulin. And nosotros request alone to hold back at an insulin-dependent type-2 diabetic amongst poorly managed blood glucose to empathise that sustained, elevated insulin levels become far darn close impossible not to accumulate excess trunk fat.”
The argue is (partly) this: Insulin stimulates an enzyme that lets obese instruct into adipose cells, in addition to it inhibits an enzyme that allows obese to instruct out of adipose cells. Talk almost a double-whammy. Insulin is similar a prison theater guard, who helps lock triglycerides into obese cells, in addition to hence stands at that spot inwards fellowship to brand certain they never instruct dorsum out. Son of a…!
This requires a fleck of explanation. Triglycerides—that is, 3 obese acid molecules connected to a glycerol backbone—are likewise large to locomote into in addition to locomote out cells freely. They can’t cross the jail mobile telephone membrane. Therefore, inwards fellowship for triglycerides to instruct into the cell, they receive got to hold upwards broken downwards into private obese acids. The main enzyme that does this is called lipoprotein lipase. Once within the cell, the obese acids reassemble themselves into triglycerides (also called triacylglycerols, or TAGs, for short). So yous run into the occupation now, right? If TAGs are likewise large to cross the jail mobile telephone membrane in addition to instruct inside, hence nosotros likely request roughly other enzyme to intermission them back down into private obese acids earlier they tin hold upwards released back out of the adipose cells. After all, that’s what nosotros want, right? Fatty acids to hold upwards released from adipose tissue so they tin hold upwards used equally fuel somewhere else, such equally inwards cardiac musculus or skeletal musculus cells—that is, we desire to lav fat.
Remember: Amy Berger, M.S., NTP, is non a Dr. in addition to , LLC, is non a medical practice. The data contained on this site is non intended to diagnose, treat, cure, or foreclose whatever medical condition.