Episode 11: Why You’re So Tired in Your 40s (and How to Change It)
Midlife fatigue often shows up in familiar ways, an afternoon crash, brain fog, low patience, slower recovery, and sleep that does not really help.
What gets blamed on aging is often something the body is missing, like iron, B12, vitamin D, or the ability to absorb nutrients well.
Long-term stress can make it even harder for the body to keep up. When the body does not have what it needs to make energy, feeling worn out is not random.
What if fatigue is not just getting older, but a sign that the body needs more support?
In this Wild as Wise episode, Sara Estes looks at midlife fatigue through a more useful lens. She explains how low iron, low B12, low vitamin D, poor digestion, and long-term stress can slowly drain energy over time.
Instead of treating exhaustion like a personal failure or something to push through, this episode helps connect the dots between symptoms and what the body may actually need.
With practical insight and a more grounded view of women’s health, Sara offers a path toward better energy, deeper understanding, and real support.
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Why You’re So Tired in Your 40s (and How to Change It)
You're climbing a flight of stairs and your heart does this thing — just a little extra effort, a little more than it should. Not pain. Not a medical event. Just your body working harder than the task requires. You're not out of shape. You know you're not out of shape. So you file it away and keep moving. But some part of you is keeping a running list.
The stairs. The afternoon wall. The eight hours of sleep that don't actually feel like eight hours of sleep.
Here's what nobody told you: that list has a nutrient profile. There are specific things your cells are likely missing — things that have nothing to do with your age or your discipline or how hard you're trying — and when you see the research on midlife women, it stops feeling like a mystery. It starts feeling like a problem you can actually solve.
That's what today is about.
[standard Wild is Wise intro plays here]
Welcome to Wild is Wise. I’m Sara Estes, a former private investigator who ditched the high‑stress legal life after a major health crisis. I rebuilt my health from the ground up through nutrition and functional medicine, and now I’m here to uncover the truth about women’s wellness and translate it so you can make informed decisions about your health. On this podcast, we break down women’s nutrition and physiology with real research and practical steps, and we keep coming back to the same idea: what’s found in nature is often exactly what our biology is wired to thrive on.
We get nerdy with the science, but we keep it real for everyday life. If you’re ready to understand what your body actually needs, you’re in the right place. As always, this podcast is educational, not medical advice, so please talk to your healthcare provider before making any changes.
Alright—let’s jump in.
This episode is for the woman who lies awake at 3 a.m. thinking, “What is happening to me? Why am I working this hard just to feel…mediocre?” Your energy is less reliable. Your digestion is touchier. Your focus and mood feel less steady. You’re wondering if this is just “getting older,” or if you’ve missed some invisible window where your body could still bounce back. I want to offer you another way to see this: midlife fatigue is very often about depleted nutrient reserves and changing absorption—not a lack of willpower.
Let’s start with what the research actually shows. When scientists look at women in their 30s, 40s, and 50s, they see some patterns. A 2024 analysis of non‑pregnant women found that iron deficiency—both with and without anemia—is still “highly prevalent” among women of reproductive age. Another paper reported that almost a quarter of pre‑ and perimenopausal women had depleted iron stores, compared with only about two percent of men. In simple terms: women are much more likely than men to be running on low iron, largely because of years of monthly blood loss and pregnancies.
Iron is not just about anemia on a lab slip. Iron is how your red blood cells carry oxygen. Ferritin—the storage form of iron—is your “iron savings account.” When ferritin is low, your cells simply don’t get oxygen as efficiently. That feels like unexplained fatigue, breathlessness walking up stairs, more hair shedding, pale, dry skin, and a heart that feels like it’s pounding faster than it should. What’s wild is that many lab ranges still call ferritin of 10 or 15 “normal” for women, even though clinicians see fatigue and hair loss over and over again in women at the low end of that range.
Iron is just one example. Vitamin B12 is another. A 2022 study of over 2,000 people—most of them women—found that about 42 percent had B12 levels below 400, which is considered sub‑optimal, and that fatigue and memory problems were significantly more common in the low‑B12 group. Other reviews estimate that somewhere between 6 and 18 percent of women are frankly B12 deficient, and the risk goes up with age, digestive issues, certain medications, and restrictive diets. B12 is essential for making healthy red blood cells and for turning the food you eat into ATP—the actual energy currency in your cells. When B12 is low, fatigue, brain fog, and mood changes are extremely common.
Then there’s vitamin D, magnesium, folate, omega‑3s, and others. An expert review in 2025 looked at 90 different studies on midlife women and found that deficiencies in nutrients like B6, B12, vitamin D, iron, omega‑3 fatty acids, and even plant compounds like lycopene were linked with a higher risk of everything from cardiovascular disease and metabolic issues to depression, cognitive decline, and osteoporosis. Another article on perimenopause fatigue noted that iron deficiency, lower B12 absorption with age, and vitamin D and magnesium shortfalls can all show up as exhaustion, poor sleep, and low mood in midlife women.
Put all of this together and here’s the picture: by the time a woman hits her 40s or 50s, she may have decades of heavy periods, pregnancies, stress, under‑eating, dieting, gut issues, and medication use behind her. Somewhere along the way, her nutrient reserves—especially things like iron, B12, vitamin D, and key minerals—got drained. Her gut may not be absorbing nutrients as well as it used to. And now, in midlife, her body is trying to navigate hormone shifts on top of a half‑empty tank.
From the outside, that looks like “I just can’t get myself to the gym” or “I’m so lazy lately.” On the inside, it’s more like, “Your mitochondria are gasping for oxygen and B vitamins. Your nervous system is running on fumes. There is nothing left to give.”
This was exactly my experience. During my fertility journey, I was working hard, going to appointments, buying supplements, eating what I thought was a pretty good diet—and I still felt wrecked. No one was talking to me about nutrient density, about ferritin, about B12, or about the fact that losing my gallbladder and living in a high‑stress state meant my digestion and absorption might not be keeping up with my needs. My fatigue wasn’t because I wasn’t trying hard enough. It was because my body didn’t have the raw materials it needed to function well.
So in this episode, I want to shift three beliefs for you.
First: from “I’m just getting older and lazier” to “my cells might be under‑fueled.” Second: from “my labs are normal, so this is in my head” to “normal ranges don’t always mean optimal for me.” And third: from “it’s too late for my body to bounce back” to “midlife is exactly when deep nutrient repletion matters most.”
Let’s take these one at a time.
The first belief shift is about seeing fatigue as a signal, not a character flaw. If you’ve had heavy periods for years, or you’re still bleeding heavily in perimenopause, there is a very real chance your iron stores are low, even if no one has said the word “ferritin” to you yet. If you’ve been on acid‑reducing medications, if you’ve had gut issues, if you’re over 40, or if you follow a mostly plant‑based diet, your B12 status deserves a closer look. If you live in a northern climate, work indoors, or avoid sun, vitamin D may be low. None of that means your body is broken. It means your biology is doing exactly what biology does when it doesn’t have enough of certain building blocks: it slows down non‑essential functions to prioritize survival.
The second belief shift is about labs. Spend five minutes in a room—or a group chat—full of midlife women and you’ll hear the same sentence on repeat: ‘My labs are normal, but I don’t feel normal.’ Often, what’s going on is that they are at the bottom of the normal range for things like ferritin or B12. On paper, a ferritin of 15 or 20 might be called normal because it’s above the deficiency cutoff. In real life, that same woman may have unexplained fatigue, hair loss, breathlessness, and restless legs. In the B12 study I mentioned, the researchers considered levels below 400 as sub‑optimal, and they still saw more fatigue and memory issues even when people weren’t technically deficient by older standards. So if you’re listening and your labs are “fine,” but you are exhausted, it is okay to ask, “Fine compared to what? Fine for whom?” It may be worth talking with a provider who understands optimal ranges, not just “you’re not in crisis, so you’re fine.”
The third belief shift is the most emotional: “Is it too late for my body to bounce back?” I want you to hear this clearly: midlife is not a point of no return. A 2025 expert panel on midlife women’s health emphasized that the menopausal transition is actually a window of opportunity—yes, there are hormone changes and more inflammation, but it’s also a prime time to address micronutrient gaps, metabolic health, and lifestyle in a way that can pay off for decades. Another article on perimenopause fatigue pointed out that addressing things like iron deficiency, B12, vitamin D, and magnesium—when they’re low—can meaningfully improve how women feel day to day. You have not missed your window. Your body is constantly rebuilding, repairing, and responding to what you give it.
So what do you actually do with all of this?
I want to give you a very simple, very doable experiment. You do not need a giant supplement stack. You do not need a 20‑step protocol. You do not need to turn your life upside down.
For the next 4 to 8 weeks, choose one daily anchor that combines better nourishment with better absorption. That anchor has three parts:
Part one: a nutrient‑dense plate, most days. We already talked about the Wild is Wise Plate in a previous episode, but the short version is: build your meals around a real source of protein, some color and fiber, and a healthy fat. For fatigue specifically, I’d love to see you:
Bring in iron‑rich foods several times a week—things like red meat, dark meat poultry, shellfish, or, if you don’t eat those, to at least be intentional about plant iron plus vitamin C.
Include B12 sources regularly—animal proteins, eggs, dairy, or a thoughtfully chosen supplement if you’re plant‑based.
Not be afraid of foods that contain natural vitamin A and other fat‑soluble nutrients, like egg yolks and liver‑containing dishes, if that fits your life.
Part two: support your gut, even in a small way. Your gut is where all of this gets decided: what gets in, what doesn’t, and how much you actually absorb. That could look like:
Adding some kind of gentle collagen source daily—a scoop in your tea, or a cup of bone broth—because collagen peptides have been shown in lab models to support gut barrier integrity under stress.
Using soothing herbs when your digestion is flared—things like slippery elm, marshmallow root, peppermint, or ginger—so your gut lining isn’t constantly inflamed while you’re trying to feed it better.
Part three: consider one targeted supplement conversation, not a shopping spree. This is where you talk with a practitioner about checking your iron status, your ferritin, your B12, maybe your vitamin D—and then have a very honest conversation about using targeted support if those are low. Our goal on this show is not to tell you exactly what to take, but to help you see that if your tank is empty, no amount of “motivation” is going to magically create energy. Your cells need raw materials.
If you do this—if you build one nutrient‑dense meal a day, gently support your gut, and begin to address real nutrient gaps with your provider—give it time. We are not talking about a three‑day detox. We are talking about giving your body eight weeks, twelve weeks, six months of steady, compassionate input after years of output.
Here is the mental shift I want you to walk away with: when you feel tired in midlife, your first question shouldn’t be, “What’s wrong with my discipline?” It should be, “What is my body missing?” Is it oxygen because my ferritin is low? Is it B12 because my gut and my medications make absorption harder now? Is it vitamin D or magnesium or just plain calories because I’ve been under‑eating for years?
You are not lazy. You are not weak. You are not failing at adulthood because you need a nap.
You are a high‑functioning woman who has spent decades giving—through work, through caregiving, through stress, through periods and pregnancies—often without getting the level of nourishment and rest your body actually needed. Midlife fatigue is often your body’s way of saying, “I can’t keep giving from an empty tank.”
You deserve more than “fine” and “functional.” You deserve to feel like yourself again.
Until next time, stay wild, stay wise.