HSOS #40: Turn Down the Heat: What the Research Actually Says About Hot Flashes

Hot flashes got you sleeping in a puddle and layering up like you're hiking Everest? You are not alone, and more importantly, you are not powerless. In this episode, Kim pulls back the curtain on what's actually happening in your body when that wave of heat hits, and why blaming your pajamas just isn't cutting it anymore. From a jaw-dropping 2021 study showing an 84% reduction in hot flash frequency with one simple dietary addition, to the truth about soy that most women have never heard, this episode is packed with real, research-backed strategies you can put to work this week. Kim breaks down which foods and nutrients can help cool things down, which everyday habits are secretly turning up the heat, and why your gut, your stress levels, and your magnesium intake are all part of this conversation. If you're done white-knuckling your way through menopause, this one's for you.

Let's talk.

Welcome to Her Season of Strength, where women over 40 reclaim their bodies, their energy, and their voices, without apologies. I'm Kim Duffy, registered dietitian, personal trainer, mom, and your biggest hype woman when it comes to aging like you mean it.

This show isn't about chasing skinny or counting wrinkles. It's about building real strength: physical, emotional, and hormonal. Each week, I'll share straight-talking nutrition tips, sustainable fitness strategies, and conversations that help you feel powerful in your skin once again.

Menopause is not an ending, it is only the beginning. This is your season of strength.

What I Cover in This Episode:

• Why your body's internal thermostat goes haywire during perimenopause and menopause
• The surprising role of estrogen's absence in triggering hot flashes and night sweats
• The 2021 study that showed an 84% reduction in hot flashes with one daily dietary change
• The truth about soy, phytoestrogens, and why the fear around it may not be justified
• Why some women respond dramatically to soy while others barely notice a difference
• The gut connection most women never hear about and how fiber plays a bigger role than you think
• Flaxseed, magnesium, omega-3s, and vitamin E — the supporting cast worth knowing about
• The everyday foods and drinks that are quietly making your hot flashes worse
• Lifestyle factors like exercise, sleep, stress, and hydration that can shift the dial significantly
• Three simple things you can start doing this week to take back some control

Links & resources for this episode:

Fit After 50+ Program: 8-Week Nutrition Coaching & Strength Program for menopausal women.  Join the interest list today for the best discounts, bonuses and updates about the next program coming Fall of 2026!

Free cheat sheet: "20 Tips to Crushing Menopause"

Join my free weekly newsletter list and get a new high protein recipe sent to your inbox every Thursday. 

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Transcript

[00:00:00] Hi there, and welcome to Her Season of Strength, where women over 40 reclaim their bodies, their energy, and their voices, without apologies. I'm Kim Duffy, registered dietitian, personal trainer, mom, and your biggest hype woman. When it comes to aging like you mean it, this show isn't about chasing skinny or counting wrinkles.

[00:00:20] It's about building real strength, physical, emotional, and hormonal. Each week, I'll share straight talking, nutrition tips, sustainable fitness strategies. And conversations that help you feel powerful in your skin. Once again, menopause isn't an ending. It's only the beginning. This is your season of strength.

[00:00:39] Hello and welcome back to Her Season of Strength. I am so happy you're here, especially for this awesome topic that we're gonna talk about today. So I should give you a little setup. So last Tuesday I did a bonus. A bonus presentation for my Fit After 50+ peeps. So I just [00:01:00] finished my third run of the Fit after 50 plus program and it just finished here last Sunday.

[00:01:08] And I gave them a bonus presentation that, was titled Nutritional Strategies. Actually it was called Feed the Change, nutritional Stat Strategies to Overcome menopausal Symptoms. We talked about things like hot flashes and brain fog and weight gain and oh gosh, let me think of fatigue. And there was one other one.

[00:01:31] I'm trying to think. My brain's a little bit slow moving today. But anyway, it was a really good discussion anyway, just. I after the fact was like, okay, I packed this with a little too much information and I need to take a bit of a step back and maybe simplify it a little bit easier so that it's easier to follow and more exciting.

[00:01:49] And but I got a lot of great feedback from the women that came and it was just really good. It is something that I think I am going to probably break it up because [00:02:00] there's so much information, but break it up into piece by piece, each symptom and kind of what nutritional strategies that we can use in order to help these.

[00:02:11] And there is thing, there are things that we can do for each and every one of 'em because there's a real physical reason why they're happening in our bodies. It isn't just. Some oh, we have no idea why this is going on. We know what's going on. But anyway, so hot flashes was, were, was one of the things I talked about.

[00:02:28] So I thought, you know what, I am just gonna take this one piece and I am gonna put it into a podcast episode because it's super interesting what you know, current science, what current research is seeing. About, about these hot flashes. I am just a normally hot running person. I seem to get hot really easy, but one of the things I noticed that was, like early in my forties before I even thought about oh, I'm in perimenopause, right?

[00:02:54] I would wake up at night, literally drenched. I would have sweat like running down my legs. I'd [00:03:00] have to change my pajamas, and I just thought, oh, I just wore too warm of jammies. Or I covered up too much with covers. And that must be why I got hot. I wasn't thinking about the fact that, oh, this is night sweats, right?

[00:03:12] Or these are hot flashes during the night or whatever. And it's so interesting, but now I can't say that I have all of a sudden. Just sweat from head to toe. But I do get hot and cold very easily, so I constantly have a, some socks or a sweatshirt or layers that I can throw on and off and on and off.

[00:03:34] It's con, it's a kind of a constant game. All day long as I'm putting a jacket on and off. But anyway, I don't know if that's the same for you and I think it's different for every person. Every person is affected a little bit differently, but so today I wanna talk a little bit about what is going on in your body when a hot flash hits.

[00:03:53] We'll talk about the role of estrogen and more specifically, its absence in this whole drama. [00:04:00] I wanna talk about the foods, the nutrients and lifestyle habits that research is showing can make a real big difference. Take a little bit of a deep dive into soy conversation and I know I did an episode here and I will link it in the show notes specifically on soy and, that'd be a good one to go back to and listen to if you haven't listened to it yet, because I think it's important. I think we have a lot of misconception about soy and its relation to breast cancer and a lot of people are avoiding it for not the right reasons. And then lastly, I wanna talk about a practical, actionable game plan that, that you can.

[00:04:39] Try this week and see if it makes a difference. By the end of this episode, you're gonna understand your body a little better. You're gonna have, a few real tools in your hands, not, guesses or not wellness trends by influencers or just some real actual e evidence. So let's dive in.

[00:04:58] So first of all, the mechanism of a hot [00:05:00] flash as our estrogen declines in perimenopause and menopause. The brain's temperature regulating center, it's called the hypothalamus. It gets hypersensitive to tiny changes in our core body temperature. So we think of that a little bit like a thermostat in your house, has a faulty sensor.

[00:05:19] So your body perceives a temperature threat that isn't really there, and it responds by rapidly dilating blood vessels near the skin surface to just get rid of heat. And what happens or what are we feeling? Then we're feeling sudden flushing, sweating, racing heart, and that wave of kind of intense warmth.

[00:05:39] Something usually followed by the chills. They can last anywhere between one and five minutes typically. And Hale happens several times a day or night. You know where we call 'em the night sweats. They can begin years before your last period, often in our mid to late forties, and usually they're driven by [00:06:00] fluctuating and declining estrogen, which destabilizes our, thermo regulatory zone.

[00:06:07] What's so interesting is this zone, which is the range where your body temperature feels comfortable, it narrows significantly in menopause. It makes us more reactive to normal temperature fluctuations. There's these two neurotransmitters called norepinephrine and serotonin, and they're also involved, and this is why stress and certain foods and drinks can be.

[00:06:34] Really strong triggers. So some of these strong triggers are gonna be like alcohol, caffeine, spicy foods, stress, heat tight clothing, surprisingly, and even certain rooms or situations. So think about it. Do you notice any patterns in your life? Do you notice you know that Oh yes, I have a glass of wine and it always will.

[00:06:59] Will [00:07:00] cause a hot flash, or maybe after you go to bed or if I have caffeine a little bit too late in the afternoon, I notice it. So let's talk a little bit about soy. 'cause I want I know some of you have been told to avoid it, some of you have been told to eat it. And I wanna give you a little bit about the actual science behind it.

[00:07:16] Soy contains these compounds called isoflavones and there's specifically genine and diet design, and they're phytoestrogens. And that sounds, oh, phytoestrogens, that's estrogen, right? It must be the same as estrogen. They have a structure similar to estrogen. Okay. Similar is the key word there. And they can bind to estrogen receptors in our body, but with a much weaker activity than actual estrogen.

[00:07:49] So think of them as this gentle nudge on that receptor rather than the full signal. So there was a big study in 2021 that was [00:08:00] published in the journal called Menopause and it's, that's, it's the Journal of the Menopause Society. And it found that low fat plant-based diet that included half of a cup of cooked soybeans per day.

[00:08:14] It reduced hot flash frequency by 84%. And it eliminated moderate to severe hot flashes in about 59% of the participants, and that's significant. And it was peer reviewed. This is like a good research backed, science that's worth highlighting. There was another meta-analysis done in 2023 and that was published by complimentary therapies in medicine.

[00:08:40] And it analyzed 17 different randomized control trials and found that soy isoflavone and supplementation significantly reduced both the frequency and severity of hot flashes compared to the placebo. Now I'm not really gonna talk about supplementing, like I, [00:09:00] I don't necessarily want you guys to start popping soy.

[00:09:03] Supplements. Okay. I don't think that is the answer here. I think looking for how we can add it in food form and research, they, it suggests that the benefit might be strongest in women who are. Equal producers, and that's about 30 to 50% of Western women and a higher percentage of Asian women.

[00:09:25] They have gut bacteria that converts the soy isoflavone, called Dine into Equal, and it's E-Q-U-O-L and it's a more, a stronger, more potent compound. And this might. Help explain why soy has such significant effects in some women, but more modest effects in others. So Japanese women who typically consume, higher amounts of soy throughout their lives report significantly lower rates of hot flashes than Western women.

[00:09:57] Though this is likely, not just [00:10:00] a one thing, one, it's probably a combination of both, diet, genetics, as well as gut microbiome factors. So the fear, you know around soy and hormones largely came from animal studies using very high concentrations of isolated isoflavones, not whole food, soy in normal dietary amounts.

[00:10:23] For most women, moderate whole food, soy consumption, like one or two servings per day of at AAMI or tofu. Tempe Miso, soy milk. It's considered safe and may be beneficial. Women with a personal history of hormone receptor positive breast cancer should discuss soy with their oncologist before increasing intake.

[00:10:44] As the data, in that population, it's a little bit more nuanced, but understanding that, just like with all other supplements, that when you're consuming it in food form, it's just a whole different world compared to just isolating it and [00:11:00] taking it in a pill form. So my recommendations are to prioritize those whole food sources, so edamame, tofu, Tempe.

[00:11:09] Miso unsweetened soy milk. You aim for maybe 20 to 25 to 50 milligrams of soy isoflavones per day, which is about one serving of edamame or tofu and process soy. So that's gonna be like your soy protein isolate in your protein bars or your highly processed soy snacks and foods. They're not gonna con it doesn't contain the same benefit profile.

[00:11:36] Okay, so now let's talk about some other foods and nutrients that help. So first of all is flaxseeds or lignins. Flaxseed contain lignins, which is another type of phytoestrogen with, it's a similar but a distinct mechanism. Studies show that like one to two tablespoons of ground flaxseed per day may [00:12:00] modestly reduce hot flash frequency.

[00:12:02] Ground flaxseed. It's far more bioavailable than the whole seeds. Okay? Crushing it right before you're taking it or purchasing the ground flaxseed. And throw it in the freezer because it can get rancid quick and easy. It helps to support gut health, great fiber, and it also has cardiovascular benefits, especially with menopause.

[00:12:24] Now fiber and the estrobolome, which is the gut, our gut microbiome, it plays a large role in estrogen metabolism through, in a collection of bacteria called the estrobolome. So a high fiber diet like veggies and beans and legumes and whole grains and fruits that supports that diverse, or variety of gut microbiome that helps regulate how our estrogen is processed and reabsorbed.

[00:12:53] So a low fiber, highly processed diet can actually disrupt the system and it can worsen those hormonal [00:13:00] fluctuations. All right, next is Omega-3 fatty acids. Research is mixed on this. Some studies suggest that maybe omega threes may help reduce hot flash frequency and mood disruption in menopause.

[00:13:13] They also have strong cardiovascular and anti-inflammatory benefits that matter huge for us ladies in midlife. So some ways that we can get those really good Omega-3 fatty acids are gonna be your fatty fish. So your salmon, your sardines, your mackerel, we're gonna get 'em in. Walnuts, chia seeds and flax seeds.

[00:13:31] Those are the biggest sources. Next, moving on to magnesium. I know last week I talked about magnesium and the importance with bone health, especially when, mixed with vitamin D and K two. If you haven't listened to that, go on ahead and listen to it. It's episode 39, but magnesium is so important in our bodies.

[00:13:52] It's involved in over 300 enzymatic processes, including our nervous system regulation. [00:14:00] There are several small studies that suggest that magnesium supplementation. Usually I recommend magnesium glycinate or maleate forms. Three, 300 to 400 milligrams before bed. They can reduce hot flash frequency and improve sleep quality.

[00:14:17] And what's surprising is magnesium deficiency is super common, especially in women who eat a diet that's higher in processed foods or who are under chronic stress. Okay. Next is vitamin E. There's been a few older but notable studies that found that vitamin E. Mixed tocopherols are approximately 400 to 800 IUs a day.

[00:14:42] Can modestly reduce hot flash frequency? It's not a magic bullet, but it's a low risk addition with additional antioxidant benefits. Vitamin E is usually not one that I'm recommending all the time, or frequently. Vitamin DI think is a little bit more important, but they're both fat soluble vitamins, [00:15:00] so that just means that compared to water soluble vitamins, which are gonna be like your B vitamins, which if we consume too much of it, we're just gonna pee it out. These can be stored in fat tissue. And also when we're consuming them, we wanna make sure we're consuming them with a little bit of fat, so it helps us to absorb them better.

[00:15:20] And those are gonna be those vitamins A, D, E, and K. Those are the fat soluble vitamins. So let's talk a little bit about what foods can make hot flashes worse. First of all is alcohol. It's a vasodilator, so it's gonna widen those blood vessels is, which is exactly what we don't want. Next is caffeine. It stimulates the nervous system.

[00:15:45] It raises our cortisol levels and it can be a direct trigger for many women. Doesn't mean you can never have it, but caffeine's one of those that, we have it in moderation. Maybe we limit it to the morning. We try not to be drinking it all day long, and especially not in the afternoon [00:16:00] when it can affect our sleep.

[00:16:01] Next is spicy foods. Capsaicin activates the same heat receptors in the hypothalamus. Yeah, so we can, you might notice that when you eat something spicy, that you're more likely to have a hot flash. Next is highly refined carbohydrates and sugar. They can spike the blood sugar, which can worsen our hormone volatility.

[00:16:22] So we understand, how important it is for us to. To focus on blood sugar regulation and control during this time in our lives because when our blood sugars are all over the place and on this rollercoaster, we are gonna notice more inflammation in our body. We are gonna notice more weight gain.

[00:16:40] We are gonna notice, decrease. It can affect our energy levels. When we have that blood sugar spike and fall, we're gonna notice that we're more fatigued. So important to, to focus on maintaining that good blood sugar control. And then lastly is processed foods that are high in sodium. This can worsen our sweating and [00:17:00] also can work to dehydrate us.

[00:17:03] So now let's talk about some lifestyle factors that can really make a big difference when it comes to hot flashes. Regular moderate exercise, so particularly strength training as well as, cardio aerobic exercise. It's been shown in multiple studies to reduce hot flash frequency and severity.

[00:17:22] It also supports our thermal regulation, meaning it's just helping our body to regulate our temperature. It's gonna reduce those stress hormones like cortisol. Improve sleep, and as always so important, maintains muscle mass as well as bone density, which these are so critical. When we hit menopause, we're shooting for a minimum of 150 minutes per week of moderate activity.

[00:17:47] Okay, next is stress and cortisol. So cortisol and norepinephrine are both implicated in triggering hot flashes. So chronic stress can keep those hormones elevated. Doing things like [00:18:00] practicing, breathing and yoga, meditation and even just incorporating in some good daily walks can significantly reduce our cortisol load.

[00:18:10] One breathing technique that you could try is just slow deep breathing, about six breaths per minute. Has been shown in clinical studies to, to reduce hot flash intensity just in the moment. That's pretty easy, right? So just nice deep breaths because so many of us are running through our day and we're just shallow breathing all day long, and we're not actually taking those nice, deep cleansing breaths.

[00:18:35] Next is sleep hygiene, night sweats, and hot flashes. They can really mess with our sleep and we know that poor sleep worsens hormonal dysregulation. So keeping our bedroom cool, maybe somewhere between 65 and 68 degrees Fahrenheit using moisture wicking, bedding, and trying to establish a nice, consistent wind down routine to decrease the [00:19:00] impact of those nighttime hot flashes.

[00:19:03] Next is alcohol and smoking. Both are clinically documented to increase hot flash frequency and severity. This isn't about perfection. It's not like you can never have a glass of wine, if your hot flashes are significantly impacting your quality of life, these are, the first lifestyle variables that are seriously worth addressing.

[00:19:25] And lastly is hydration. Dehydration or not getting enough fluids in can worsen your hot flash intensity. So the sweating during our hot flashes also accelerates fluid loss. So we're trying to shoot for drinking at least eight to 10 cups of water a day and more if we are exercising and making sure that, if we're sweating overly heavily, we're making sure that we're incorporating in those good electrolytes into our fluids.

[00:19:51] And that's sodium, potassium, magnesium. Those are really important too. So I just to bring this [00:20:00] around, recap this hot flashes, they are caused by real physiological responses to those hormonal changes or that the estrogen spiking and falling up and down and up and down is and just in general going down, not just something that we have to just deal with and white knuckle it through.

[00:20:18] Right? There's things that we can do. Soy isoflavones have some of the most compelling evidence of any dietary intervention with studies showing significant reductions in frequency and severity with those populations that are consuming soy more often, especially in those whole food sources, making sure we're supporting our gut microbiome.

[00:20:42] And how we do that is we're eating those good fiber. Shooting for 25 to 30 grams of fiber per day in the whole food form, and that's gonna help regulate how our body is handling that estrogen. What is being reabsorbed? What is being [00:21:00] excreted and flaxseed. Magnesium, omega threes and vitamin E can all have kind of supportive roles.

[00:21:07] They can be generally helpful. Some things that we eliminate can make a big difference, as big of a difference as what we add. So trying to decrease alcohol, refined sugar, and spicy foods. And then making sure that we're finding ways to manage our stress. Sometimes we can't get rid of stress, right?

[00:21:29] It's oh, I have this high stress job, or I have, lots of little kids running around, or grandkids or, I have a stressful life. We can't always change those things, but we can change how we manage it. We can change how we deal with it. Are we taking time for ourselves? Are we doing self care?

[00:21:48] Are we getting outside and feeling the sunshine on our face and going for just a nice leisurely walk. These things are all so important. They are core strategy in helping us to [00:22:00] deal with stress and then just, and also just getting in that movement. It's huge when it helps to, when it comes to, regulating our thermostats.

[00:22:10] So what are some things that you can, start with just three simple things you can start with. One would be add one serving of whole food soy daily. So maybe you throw some edamame on your salad or maybe you throw some tofu on, your lunch or dinner meal. Or maybe you put it in a scramble for breakfast.

[00:22:30] Maybe you make soup with me soup with miso. Those are three easy ways to do it. Next, you can stir in a tablespoon of ground flaxseed into your morning yogurt or your oatmeal or into your smoothie. And third would be start tracking your personal hot flash triggers for one week, and just notice patterns around food and stress and sleep and alcohol or caffeine.

[00:22:54] Because these hot flashes, they're your body that it's trying to communicate a significant [00:23:00] hormonal shift. You don't have to suffer quietly and you don't have to immediately reach for medication as your only option though. For some women, that absolutely is the right call, and there's no shame in that either.

[00:23:11] What I want for you is options, right? I want information, I want agency, and that's what we're building here together. So if this episode helped you, please take 30 seconds, share it with a friend, or leave a review. I would really appreciate it. It just helps other women to find the show. And if you haven't followed it yet, hit that button so you never miss an episode.

[00:23:32] Remember, this is about progress over perfection. And we're in this for the long haul. This is your season of strength. Have a great day.