CHAPTER 5:
HEALTHY HORMONES, HEALTHY YOU
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“Just finished my Whole30, and my (diagnosed type 2 diabetic) blood sugar levels are now normal—completely normal. I have cut my diabetes medications in half, and my blood pressure is in the normal range too. All of my pain, stiffness, soreness, and puffiness is gone… and I lost twenty-five pounds. The Whole30 has changed my life.”
—Alan H., East Bremerton, Washington
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Our second Good Food standard states that the food you eat should produce a healthy hormonal response in the body. This is probably the most science-y section of the whole book, but as promised, we’ll use a lot of analogies and examples to make the science easy to understand. We’re also going to simplify things quite a bit, because you don’t need to understand how everything works to know how to apply it.
Let’s start with some basics.
HORMONES
Hormones are chemical messengers that are usually transported in your bloodstream. They are secreted by cells in one part of the body and bind to receptors in another part of the body. (Think of a courier carrying a message from one person to another.) Hormones have many roles, but one essential function is to keep things in balance.
Essentially all biological processes have regulatory mechanisms designed to keep systems operating within safe, healthy parameters and maintain homeostasis (equilibrium) in the body. Think of the thermostat in your house. The furnace kicks on to keep the temperature above the lowest point set, but as the temperature rises to the top end of the range, the thermostat turns on your fan or air conditioner. Much as your thermostat keeps your house within a “healthy” temperature range, hormones work in delicate, intertwined ways to maintain homeostasis in your body.
Hormones also respond to any external factor that tips the scales out of balance. To go back to our thermostat analogy, opening a window in wintertime will push the temperature in your home off balance. The act of opening a window sends a message (“It’s getting cold in here!”) to your thermostat, which reacts to that stimulus with an internal correction (firing up your furnace). When the temperature reaches the normal range again, your furnace then turns off.
When you eat and digest food, various biochemical components of the food trigger multiple hormonal responses in the body. These hormonal responses control the use, storage, and availability of nutrients—where they go and what happens when they get there. Different nutrients cause different hormonal responses, but all of those responses are intended to correct the shift in balance caused by the influx of digested food particles.
ONE BIG TEAM
While there are a lot of hormonal players, for the sake of simplicity, we’re going to talk about only four in detail:
Insulin, leptin, glucagon, and cortisol.
These four hormones (along with many others) form a complex, elegant—but not indestructible—web of feedback loops that influence all body systems. They all interact with one another’s functions, behaving like a team in the body. These hormones are neither “bad” nor “good” in the right amounts. Things get ugly, however, when you’ve got too much or not enough of any given hormone.
Let’s start with both insulin and leptin, as it’s hard to separate these two.
INSULIN
Summary: An anabolic (“building, storing”) hormone secreted by the beta cells of the pancreas in response to ingestion of energy, most notably from carbohydrate. Insulin facilitates the moving of macronutrients (protein, fat, and carbohydrate) from the bloodstream into cells for immediate or future use, and coordinates the metabolic shift from predominantly burning one fuel source (carbohydrate) to the other (fat). Chronically elevated insulin levels are correlated with leptin resistance and indirectly related to elevated cortisol levels.
Insulin is about as close to a “master hormone” as you can get. It acts on virtually all cells in the body and directly controls or influences energy storage, cell growth and repair, reproductive function, and, most important, blood sugar levels.
Insulin “unlocks” a one-way door into cells so they can store or use nutrients. Insulin effectively stores all macronutrients—protein, fat and carbohydrates—but its secretion is most closely tied with carbohydrate ingestion.*
When we eat carbohydrate, it is broken down in our bodies into simple sugars and then absorbed into the bloodstream. This leads to a rise in the amount of circulating blood sugar (glucose).
To be optimally healthy, our blood glucose levels must be kept within a normal range—not too low, not too high. Remember, just as in the thermostat analogy, “normal” is pretty much synonymous with “healthy.” In the case of regulating blood sugar, your pancreas is the primary thermostat, and insulin is like your air conditioner, keeping blood sugar levels from remaining too high.
A rise in blood sugar is sensed by beta cells in the pancreas, which then secrete insulin into the bloodstream. Insulin signals cells in the body to pull glucose out of the bloodstream and move it into storage, bringing blood sugar levels back to a normal, healthy range. Elevated insulin levels also have a satiety function, reducing hunger.
INSULIN SENSITIVITY
The scenario we just described is called insulin sensitivity. If you have a healthy metabolism, when you eat a healthy meal, your blood sugar levels rise moderately—not too much, and not too fast. When blood sugar increases, the pancreas dispatches just enough insulin to communicate to the cells exactly how much blood sugar needs to be stored. Insulin’s message is, “Store these nutrients.” The cells, which are sensitive to the insulin message, hear the request and respond appropriately by pulling blood sugar out of the bloodstream and storing it, thereby returning blood glucose levels to normal.* Insulin sensitivity is indicative of a nice, normal, healthy relationship between the pancreas and most tissues in the body.
Insulin’s management of blood sugar serves a very important function, as chronically elevated blood glucose levels are highly damaging to many body systems, including the liver, pancreas, kidneys, blood vessels, brain and peripheral nerves. Got that?
Chronically high levels of blood sugar (hyperglycemia) are harmful, so managing blood sugar is critical for long-term health.
Once cells have taken glucose out of the bloodstream, that glucose can either be used for energy or stored for future use. The primary place to store glucose is in the liver and muscles, as a complex carbohydrate called glycogen. If stored in the liver, glycogen can easily be converted back into glucose and released back into the bloodstream when energy is needed. However, glycogen stored in muscle cells can’t be emptied back into the bloodstream—it stays there, to provide fuel for your muscles. (Which is good, because your muscles can do a lot of hard work!)
GLYCOGEN STORES
Your body’s storage tanks for carbohydrates (the liver and muscles) are kind of like the gas tank in your car. When your gas tank is full, it’s full. It can’t get any bigger, and you can’t make it any fuller. Your body’s carbohydrate fuel tank, however, isn’t very big—you can store only enough glycogen to maintain hard, continuous activity for about 90 minutes. And because carbohydrate is fuel for intense activity, you don’t tap into your glycogen stores in any meaningful way while you’re sitting at your desk at work, watching television, or puttering around the house. In other words, it’s really easy to fill your tank up with carbohydrates—but if you’re not doing lots of high-intensity activity, you’re not really using much fuel!
Your hormonal troubles start with “overcarbsumption”: the chronic overconsumption of supernormally stimulating, nutrient-poor, carbohydrate-rich foods.
To begin with, a constant excess supply of carbohydrates will tilt your metabolic “preference” toward burning what’s most plentiful—sugar—when fuel is needed. If there is an overabundance of sugar, the sugar takes precedence over fat as a source of energy in many metabolic processes, and stored fat doesn’t get burned for energy.
If less fat is being burned for fuel, then it accumulates, and body fat levels tend to increase.
In addition, all that excess glucose poses a storage problem in the body. If there’s space available in the liver and muscle cells, they’ll happily uptake glucose. However, if those cells are already full of glycogen, they will politely decline any additional nutrition (essentially putting up a No Vacancy sign). When there is no room in the liver and muscle cells, the body shifts fuel storage to Plan B.
You will not like Plan B.
When the liver and muscle glycogen stores are full, the liver (and your fat cells) converts the extra glucose into a type of saturated fat called palmitic acid, which can then bind together in groups of three (with glycerol) to form triglycerides.
These two processes combined—the preferential burning of carbohydrate over fat for fuel and the creation of triglycerides—lead to increased body fat and increased triglycerides and free fatty acids in the blood, neither of which is desirable or healthy. And this pileup of sugar and triglycerides in the blood pushes another hormone, leptin, out of balance.
LEPTIN
Summary: An “energy balance” hormone that is secreted primarily by fat cells and is released in proportion to the amount of fat stored. Leptin tells the brain how much body fat is stored and regulates both energy intake and energy expenditure to keep body fat levels in balance. Overconsumption of nutrient-poor, supernormally stimulating carbohydrates leads to chronically elevated triglycerides and blood sugar levels, which promotes leptin resistance and an increase in fat storage, accompanied by greater insulin resistance.
Leptin is sometimes referred to as a “satiety hormone,” because higher leptin levels help to keep us full and satisfied. Leptin levels follow a normal daily cycle tied primarily to your eating schedule. Since you don’t eat while you’re asleep, leptin is pretty low first thing in the morning. This triggers the secretion of appetite-stimulating hormones and is one of the reasons we wake up hungry. When you’re done eating for the day (typically after dinner), leptin levels are higher, helping you stay full and satisfied until bedtime.
However, leptin’s primary job is to regulate your big-picture hunger and activity levels to help keep your body in “energy balance”—not too fat, not too lean. Body fat is not a bad thing—it’s what allows us to survive long periods of food shortage (or to not eat for a few days when we have the flu). But our bodies are pessimists. Our DNA always expects, despite the surplus of readily available energy right now, that food will run out soon, and so the only way to survive this coming famine is to store some energy as fat. It’s as natural as breathing.
24-7-365
For those of us in the developed world, the idea of a “food shortage” sounds silly. Maybe you’re thinking, “Why hasn’t my brain caught on to the fact that food is everywhere these days?” The fact is, for thousands of years, we worked hard for the food we ate—and there were no guarantees that our food supply could be taken for granted. We’re back to ancient signals in a modern world, where the brain continues to send biologically appropriate messages to ensure your survival, despite the fact that you are now living in a wholly unnatural food landscape.
As fat is a storage depot for energy, it is important for your body to have a way to measure how much energy (fat) is available at any given moment. Fat cells do this by secreting leptin, as a way to communicate to your brain whether you are too fat, too lean, or just right. Based on leptin’s critically important message, your brain constantly gives you subconscious directions, which drive your food-seeking behavior and physical activity levels.
If you have very little body fat—perhaps too little to survive a potential food shortage—leptin levels are low. The relative absence of leptin’s message tells the brain, “I don’t have enough body fat!” Your brain then tells you to eat more and move less, which serves to change your behavior until your body fat is within a safer range. You become hungrier (and probably eat more), your metabolism slows down (thanks in part to changes in your thyroid hormone levels) and you start to gain body fat.
As body fat continues to accumulate, leptin levels rise, and your fat cells start to send more messages to your brain—“OK, we’ve got enough energy stored now!” If that message is properly received (i.e., you are sensitive to the leptin message), your brain then tells you to increase your activity and makes you less hungry, so you move a little more and eat a little less, and don’t gain too much weight.
Although it’s much more complicated than this simple summary, this energy-balance system is naturally designed to keep your body fat levels “just right.” The trouble starts, though, when the foods you’re eating promote an unhealthy psychological response, leading to chronic overcarbsumption.
Shall we recap?
When you chronically overconsume food-with-no-brakes, it floods your system with glucose. With sugar in such large supply, it is burned first for energy—which means fat takes a metabolic back seat and accumulates. This leads to a buildup of triglycerides in the liver, and increased glucose and triglyceride levels in the bloodstream. But how does this lead to problems with leptin?
The excess glucose and triglycerides in the bloodstream make their way to parts of your brain and start impairing your brain’s ability to “hear” the leptin message. This leads to a condition called leptin resistance.
THE SKINNY-FAT
If you’re overweight, it’s very likely that you’re leptin resistant—but you don’t have to appear overweight to fall into this camp. Accumulation of visceral fat (fat stored in and around your organs) is enough to promote hormonal dysfunction, including leptin resistance. We call these folks “skinny fat”: not visibly overweight, they still have an unhealthy amount of body fat, comparatively little muscle mass, and a serious degree of hormonal dysfunction, including out-of-whack thyroid and reproductive hormones.
Leptin resistance is like a hormonal conversation gone haywire. Normally, when you’ve accumulated adequate body fat, your fat cells send a message (via leptin) to your brain that says, “Hey, we’ve got enough energy stored, so you should eat less and move more.” But when receptors in the brain and other tissues become less sensitive to leptin, those messages don’t get through. Your brain doesn’t hear leptin say that you’ve got enough body fat stored.
Which means your brain thinks you’re too skinny.
Imagine that your brain is blind, unable to see your chubby reflection in the mirror or the creeping number on the scale. It needs leptin to give it the facts it can’t see. So until the brain hears leptin say, “OK, we’re fat enough,” the brain is going to keep telling you to eat more and move less, to ensure your survival.
Remember, it’s pessimistic. And without that leptin message, your subconscious brain will continue to direct your behaviors as if you were too lean—despite the fact that you know you’re gaining too much weight.
NIGHT MUNCHIES
Leptin’s message (or lack thereof) is stronger than your willpower. You may see that you’ve gained some weight, and try to eat less … but the brain’s directives are far more powerful. In fact, a hallmark of leptin resistance is uncontrollable cravings after dinner—you try to eat healthy all day, but come 8 p.m., your pantry or freezer is impossible to resist. This isn’t a lack of willpower on your part—it’s your brain responding to leptin’s primal signals, and constantly undermining your conscious decisions.
Leptin resistance means that you are gaining fat and swimming in leptin—but your brain is clueless, so it turns your metabolism down to conserve fuel, and tells you to eat more. And isn’t this all too easy to do when supernormally stimulating, nutrient-poor, carbohydrate-rich foods are whispering in your ear? Of course, overcarbsumption only promotes more sugar-burning for fuel, additional accumulation of body fat (and the conversion of excess carbohydrates to fat), and even-higher triglyceride levels in the blood.
Which makes your leptin resistance worse.
And … takes us back to insulin.
BACK TO THE START
Remember insulin sensitivity? This is when insulin’s message to “store nutrients” is heard clearly by the cells, which remove glucose from the bloodstream and store it, keeping blood glucose levels from getting (or staying) high.
In contrast to insulin sensitivity, there is also a condition called insulin resistance. And …
Leptin resistance leads to insulin resistance.
Let’s recap: You chronically overconsume, because supernormally stimulating, nutrient-poor food has no brakes. This makes you leptin resistant, which means your brain thinks you are too lean (even if the mirror tells you otherwise). This leads your brain to tell you to eat more and move less, which promotes further overconsumption. You are now metabolically reliant on sugar for energy, you continue to accumulate fat in the body and the liver, and have excess glucose and triglycerides in your bloodstream.
All of that excess glucose needs to be stored. The trouble is, jamming lots of energy into a cell causes damage. So to protect themselves from being “overfilled,” the cells become insulin resistant. Once this occurs, the cells lose their sensitivity to insulin’s message to store nutrients: the pancreas sends a message (via insulin) to “store,” but the cells don’t listen, and blood sugar levels remain high.
Since high levels of blood sugar are very unhealthy, the body really needs the cells to store that energy—so it responds with an even stronger message. Insulin resistance requires that the pancreas produce even more insulin, until the message is strong enough to force nutrients into the already-full cells. However, this “force-feeding” creates oxidative stress and elevated fat levels in the blood, which further damages the cells. The damaged cells continue to try to protect themselves, further increasing insulin resistance … and the cycle continues.
SYSTEMIC INFLAMMATION
These cells, overfilled and running mostly on sugar, produce “reactive oxygen species” (which you probably know as “free radicals”), which cause cellular damage. The response to this damage is a cascade of immune responses, including the release of inflammatory chemicals, as well as immune cells that show up as “first responders” to help repair the damaged tissue. This immune response is termed systemic inflammation (we’ll get to this soon), and further increases insulin resistance.
At this point, you have excess glucose in a system that is insulin resistant. Blood sugar remains high because the cells are stuffed and resisting insulin’s message to store. This creates ongoing hyperglycemia—chronically elevated levels of blood sugar. Which, as you recall, is very damaging—specifically to pancreatic beta cells, where insulin is produced.
Chronic hyperglycemia first causes beta cell adaptation, to allow the pancreas to produce progressively more insulin to manage the excess blood sugar. The pancreas can’t adapt forever, however. Eventually, damaged by ongoing hyperglycemia, pancreatic beta cells start to disintegrate. Yes, they actually die from toxic levels of blood sugar and the resulting oxidative stress.
At this point, you lose the ability to produce enough insulin to manage blood sugar—which is how toxic levels of blood sugar and insulin resistance can lead to type 2 diabetes.
However, there are consequences to your health long before you get to diabetes. Hyperglycemia (chronically high levels of blood sugar) is damaging, but hyperinsulinemia (chronically high levels of insulin) is profoundly damaging, and a clear risk factor for major lifestyle-related diseases and conditions, like diabetes, obesity, heart attack, stroke, and Alzheimer’s disease.
Chronically high levels of insulin are harmful, so
managing insulin levels is critical for long-term health.