Intermittent Fasting Explained: Benefits, Risks, Weight Loss & What Doctors Really Think

Summary

Podcast Summary: "Intermittent Fasting Explained: Benefits, Risks, Weight Loss & What Doctors Really Think"

Podcast: Health vs Hype with the American Medical Association
Host: Trace Dominguez (D)
Guests:

• Dr. Jennifer Shriver (A), Family Physician & Obesity Medicine Specialist
• Jen Stevens (C), Intermittent Fasting Author & Advocate
• Al Kavadlo (B), Fitness Influencer & Personal Trainer
  Episode Date: June 23, 2026

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Overview

This episode explores the science, myths, and real-world implications of intermittent fasting (IF). The host and guests dive into popular claims, personal experiences, and current medical evidence, addressing questions like:

• What is intermittent fasting?
• Are the health benefits real or overhyped?
• Who might benefit from IF, and who should avoid it?

The episode features a mix of personal stories, medical insights, and myth-busting, all aimed at helping listeners make informed choices about fasting and overall health.

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Key Discussion Points & Insights

1. What Is Intermittent Fasting?

[00:18, 05:46]

• IF is not defined by what you eat, but when you eat.
• Common variants:
  • 16:8 (16hr fast, 8hr eating window)
  • OMAD (One Meal a Day)
  • 5:2 (5 days regular eating, 2 calorie-restricted days)
  • Alternate day fasting, juice fasts, etc.
• Jen Stevens: “Diet is what you eat. Intermittent fasting is when you eat.” [00:18]

2. Personal Stories: Motivations and Experiences

[01:54, 04:51, 06:24]

• Jen Stevens: Turned to IF after years of ‘yo-yo dieting’; lost weight and maintained it for 10+ years. [04:51]
  • “For the first time in my entire life, I have not yo-yoed.” [05:22]
• Al Kavadlo: Began by skipping breakfast, progressed to eating once a day. Emphasizes flexibility, not strictness:
  • “If there’s a day where I am absolutely famished, I’ll eat a snack in the middle of the day. It’s fine.” [06:24]

3. Hunger: The Body Adapts

[06:53, 08:22]

• Hunger isn’t just about an empty stomach; hormones, habit, stress, and other factors play a role.
• Both guests noted hunger comes in waves and can fade even without eating:
  • Jen Stevens: “For intermittent fasters... you have a little wave of hunger, you acknowledge it, you do something else, and then you’re not hungry anymore.” [08:32]

4. IF: Diet or Lifestyle?

[09:18, 10:30, 11:11]

• Jen argues IF is a lifestyle, not a “diet.”
• Dr. Shriver: Disagrees somewhat: “If that’s a claim for intermittent fasting, I would classify it as a diet. We try not to use the word diet because it just has a negative connotation... Lifestyle is permanent.” [10:35, 11:11]
• Emphasis: Sustainable health plans should be adaptable and fit real life.

5. What Happens to the Body During IF?

[12:00, 13:07]

• Body shifts from burning glucose (from food) to using stored fat during fasting periods.
• Early weight loss is often due to reduced calorie intake if meals are skipped and not replaced.
• IF may temporarily improve insulin sensitivity, but comprehensive, long-term benefits remain unconfirmed.
  • “There really isn’t any significant difference in weight loss... versus just calorie restriction.” [14:53, Dr. Shriver]

6. Comparing IF to Other Weight Loss Methods

[14:53, 27:46]

• IF is not superior to standard calorie restriction for weight loss or metabolic health.
• Medical weight loss drugs often result in more significant weight loss compared to IF over 12 months:
  • IF: ~3–6% weight loss at 6–12 months
  • Medications: Can be 10–18%+ (e.g., GLP-1 agonists) [27:46]

7. Claims and Evidence: Cognitive Benefits, Longevity, Autophagy

Mental Clarity:

• Anecdotal reports (“my mind gets sharper”) are common, but high-quality data does not support better cognitive function from IF versus regular eating. [17:02–18:14]
  • “It’s very neutral in healthy adults in general… best evidence for cognition is still exercise and sleep.” [17:29, Dr. Shriver]

Longevity & Cancer:

• Promising animal data, but insufficient high-quality human studies to support claims of longevity or cancer prevention. [15:48]

Autophagy:

• “There’s no good studies that that happens in humans.” [23:26, Dr. Shriver]
  • Fasting may upregulate autophagy (cell cleanup) in animals, but the topic is oversimplified online.

8. Risks and Who Should Avoid IF

[24:12]

• Dr. Shriver: “Anyone with a history of eating disorder really should be cautious... anyone with diabetes should do it cautiously... anyone who is older, or has nutritional deficiencies, or low muscle mass.” [24:17]
• Risks of IF include difficulty meeting nutrient needs, potential energy/focus dips, and impacts on sleep.

9. Guidance for Patients & Clinical Nuance

[25:31, 30:56, 31:36]

• IF may be useful for individuals seeking structure, but quality of diet, physical activity, sleep, and mental health are more important for long-term health.
• It’s not a “reset”:
  • “It’s more of a marketing phrase really than a medical one... Any benefits will tend to level off as our body adjusts. We can’t permanently reset anything.” [30:12, Dr. Shriver]
• Decision to try IF should be made with a healthcare provider.

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Notable Quotes & Memorable Moments

• Jen Stevens:
  • “It is completely different than anything else I ever did.” [05:22]
  • “The best part about intermittent fasting is that it isn’t a diet at all... It’s definitely not a diet. Like, I never say I’m doing the intermittent fasting diet.” [09:18]
• Al Kavadlo:
  • “It never feels like I’m depriving myself. It never feels like I’m starving myself.” [06:24]
  • “Your mind just gets a little sharper. Everything seems to get a little sharper.” [17:02]
• Dr. Shriver:
  • “There really isn’t evidence to show that [intermittent fasting is] a better plan than others or that it’s really even good for one.” [18:20]
  • “Our body is very highly adapted and doesn’t reset in any permanent way.” [30:12]
  • “Anyone with a history of eating disorder really should be cautious.” [24:17]
• Trace Dominguez:
  • “If weight management is your goal, there are better, more researched methods like quality of diet, physical activity, and medical options to consider.” [31:41]

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Timestamps for Key Segments

• [00:18] – What is IF? Variety of fasting approaches
• [04:51] – Jen Stevens describes her journey to IF and weight loss maintenance
• [06:53] – Scientific explanation of hunger, hormones, and adaptation
• [10:16] – Medical perspective: IF as diet vs. lifestyle
• [12:00] – Physiological changes during fasting; fat burning and insulin
• [14:53] – Evidence: IF vs calorie restriction and weight loss drugs
• [17:02] – Anecdotes and evidence on cognitive effects
• [20:13] – “Fasting goals” (insulin, fat burning, autophagy): expert fact-check
• [24:12] – Risks and who should avoid IF
• [25:31] – Doctor-patient conversations about IF, integrating with nutrition, exercise, and medication
• [27:46] – IF compared with modern obesity medications; real-world effectiveness
• [30:12] – IF as “metabolic reset”: mythbusting
• [31:36] – Personalized medicine: IF as a tool, but not for everyone

---

Takeaways

• Intermittent fasting may help some people with weight loss, mainly due to calorie reduction, not metabolic magic.
• No strong evidence for IF improving longevity, cognitive function, or cancer prevention in humans.
• Risks exist—it is not appropriate for everyone; consult your doctor, especially if you have chronic conditions or a history of disordered eating.
• Healthy diet quality, physical activity, and (in appropriate cases) medication are often more impactful for lasting health improvements.
• Approach popular wellness trends critically: Science often lags behind hype.

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For more science-backed health information, visit amahealthvshype.org.

Transcript

[A]

Ruby,

[B]

it freaks people out sometimes. What, you don't eat breakfast? What, you don't eat lunch either? Are you insane? Are you dying? Like, people cannot wrap their head around the way that I eat.

[C]

Diet is what you eat. Intermittent fasting is when you eat.

[A]

I've had a patient claim that fasting was the only way she could lose weight.

[D]

Intermittent fasting might feel like the latest wellness craze, but humans have actually been doing versions of it for thousands of years. Sometimes for religion, sometimes for survival, sometimes even for politics and protests. But over the last couple of decades, fasting has gone fully mainstream. Now it's all over TikTok, YouTube and fitness culture, with people claiming it can help you lose weight, boost your energy, improve your focus, and optimize your health. The problem is intermittent fasting can mean almost anything. Aside from your three square meals a day, there's 16, eight, where you fast for 16 hours daily and restrict your eating to an eight hour window. There's Omad, one meal a day, alternate day fasting, five, two fasting. That's five days of eating a typical diet and two of eating a calorie restricted diet. There are juice fasts. Basically everybody has their own version. So when there are this many options, what actually counts as fasting? Are we really just restricting calories? Is there something else going on? And more importantly, is intermittent fasting good for your health? Or is this another wellness trend getting way ahead of the science? Clearly we have questions. Like I said, it might just depend on who you ask. Alkavadlo, an online fitness influencer and personal trainer, shapes his entire life around intermittent fasting. He follows a version called omad, or one meal a day.

[B]

So it started by postponing breakfast, and then it became skipping breakfast, and then it became skipping breakfast and lunch. And for the most part, I eat one meal a day.

[D]

Then there's Jen Stevens, a former elementary school teacher who got so into intermittent fasting that she turned it into a whole second career. She's written multiple bestselling books on the topic, built a massive online following, and now hosts a podcast dedicated to the intermittent fasting lifestyle.

[C]

I was on that yo, yo. I was either gaining or losing. And since I lost the weight with intermittent fasting over 10 years ago, I am steady and it just feels amazing.

[D]

And of course, doctors know what's science and what's bunk. People like Dr. Jennifer Shriver, a family physician at Sanford Health who specializes in obesity medicine and long term weight management. She spends a lot of time separating what intermittent fasting can do from what social media claims it can do.

[A]

They think that intermittent fasting might optimize their health so that they can live longer, or they're just looking for that structured, easy to follow approach. And they want to work on their health. And that seems the simplest way to do it.

[D]

Welcome back to Health versus Hype with the American Medical Association. I'm your host, Trace Dominguez. Today we're talking about intermittent fasting. What is it? Can skipping breakfast really improve your health? What does intermittent fasting do to your body? Join me as we find out whether intermittent fasting is all health or just hype.

[A]

This is an iHeart podcast, Guaranteed Human. Your social media feed delivers plenty of advice, but it doesn't know you. It doesn't ask questions. It doesn't give physical exams or order tests doctors do. At the American Medical association, we believe the best care starts with a real conversation, with someone who understands the science and your unique health. So stay curious, ask questions. But when it's time to make decisions, make them with a doctor. Learn [e-mail] that's amahealthvshipe.org.

[D]

For millions of people, intermittent fasting isn't just a diet. It's become a lifestyle. And few people embody that more than Jen Stephens, who discovered intermittent fasting while trying to lose weight after years of struggling with traditional dieting. But while stories like hers have helped fuel the trend's explosive popularity online, doctors and researchers are still working to understand exactly what fasting does inside the body. I want to start by understanding why someone would want to adhere to such a strict way of eating. For that, let's hear from Jin.

[C]

I have a background, probably like a lot of women and men, in that I was always chasing the next best diet plan. Right? You know, the first time I needed to do a diet turned to calorie counting like most people. But that didn't work. It wasn't sustainable. I tried literally everything that came along. I was officially obese. I weighed 210 pounds and I was sick of it. And so of course I heard about intermittent fasting. A few people were talking about it, and I tried it.

[B]

And.

[C]

And I have never stopped since. So I've been doing intermittent fasting since August of 2014 without stopping. And for the first time in my entire life, I have not yo yoed. I've been able to maintain after I lost 80 pounds, I've been able to maintain since I lost the weight. So it is completely different than anything else I ever did.

[D]

So what is intermittent Fasting for people who might not know, well, it's basically

[C]

when we intentionally have periods of time when we choose to fast, and then we have periods of time when we choose to eat in an eating window. So we are either intentionally fasting or our eating window is open and we are intentionally eating. It's basically a boundary around the times that you're eating.

[D]

Jen came to intermittent fasting to lose weight, but many followers of this lifestyle have found their way to intermittent fasting through wellness and fitness advice. Al Cavadlo is an influencer who focuses on exercise for men in their 40s who are looking for new ways to stay fit and healthy.

[B]

Fitness and exercise was my kind of my gateway into being interested in nutrition. I got more into improving the quality of the food I was eating and also starting to pay more attention to the fasting aspect. It all happened very naturally for me. It never really felt forced. It never feels like I'm depriving myself. It never feels like I'm starving myself. And to be frank, I'm not super dogmatic about it. If there's a day where I am absolutely famished, I'll eat a snack in the middle of the day. It's fine.

[D]

I want to take a break here and talk about hunger for a minute. It's more complicated than simply having an empty stomach. People feel hunger because the body and the brain are constantly working together to monitor our energy needs. One of the biggest players is a hormone called ghrelin. It's often nicknamed the hunger hormone. When your stomach has been empty for a while, ghrelin levels rise and send signals to the brain telling you it's time to eat. But blood sugar levels, hormones, sleep, stress, emotions, habits, and even smell can all influence hunger too. For example, if you have a habit of always eating lunch at noon, your body may start triggering hunger signals around that time, whether you actually need calories or not. During fasting, people often notice hunger comes in waves rather than increasing endlessly. That's because hormones like ghrelin rise and fall throughout the day, and the body can gradually adapt to new eating patterns over time. Al alluded to this a little Just

[B]

try to wait a little longer to eat breakfast. Because most people wake up and immediately start eating. They're not hungry. They do it because it's part of their routine. And if you actually are hungry 15 minutes after you wake up, God bless, eat. But sometimes people find out, oh, you know what? I drank a glass of water and I didn't get hungry for a couple hours. And that's sort of how it happened for me, and I've been doing that for a long time now.

[D]

Jen shared something similar.

[C]

The thing about hunger is, let's imagine you're not an intermittent faster. You're just someone who eats. Typically, yeah. Do you have hunger in your day?

[D]

Sometimes, yes, you do.

[C]

You have hunger. It comes and then you eat, and then it goes away, and then later you're hungry again, and then you eat and then it goes away. For intermittent fasters, we have hunger too, and then it goes away. It fades without eating. And your body's like, all right, I guess I'll munch on some stored fat for a while. So the thing about hunger is, once you understand, it doesn't build and build and build and build. When you're fasting clean, it's not an emergency. You have a little wave of hunger, you acknowledge it, you do something else, and then you're not hungry anymore.

[D]

And let's face it, for all of us, but especially for people trying to lose weight, specifically evolving diet information and guidelines can feel confusing.

[C]

You know, should you be vegan? Should you be carnivore? You know, are plants trying to kill you? I mean, you know, I could talk about every single diet out there and what they want you to avoid or what you're allowed to have or not allowed to have, but we get so confused. We don't even know what we're. What we're supposed to be eating anymore. But the best part about intermittent fasting is that it isn't a diet at all. Because diet is what you eat. Intermittent fasting is when you eat. So we're all eating a diet, whether it's the standard American diet, or you're vegan or you're carnivore, or you're following the Mediterranean diet, you're eating some sort of diet. But intermittent fasting is when. So it's definitely not a diet. Like, I never say I'm doing the intermittent fasting diet.

[D]

I wanna introduce our medical expert now, Dr. Jennifer Shriver. She's been a family physician and obesity medicine specialist for more than 20. I played that clip from Jen for her, and here's Dr. Shriever's reaction to it.

[A]

You know, nutrition is complex, and it kind of seems like, I'm sure, to the normal population that our nutrition advice has changed a lot across the years. I mean, low carb, then low fat. So that's very confusing.

[D]

And she's saying that because it's when you eat, it's not a diet.

[A]

That seems like a strange way to represent that. I guess it depends on how you think of the word diet. I mean, historically diet is something that helps you lose weight. And if that's a claim for intermittent fasting, I guess I would classify it as a diet. We try not to use the word diet because it just has kind of a negative connotation and it's something that you do temporarily. Right. And maybe that's what she's trying to say too.

[D]

She definitely talks a lot more about how this is a lifestyle change and diets are temporary and lifestyle is, you know, permanent.

[A]

Yeah. In my practice treating patients for weight management, I'm trying to create and help you improve your lifestyle in a way that you feel good in the process, lose weight, have more energy. I don't want to have a plan that you graduate from or finish. This is something that we might continually have to adjust and manage over time. So I think even people on intermittent fasting are going to find that they're going to have to adjust and adapt something over time. So that's giving the sense that this is a long term solution. Life happens, life changes. Some of that's under our control. A lot of it's not. There's nothing that is the final answer.

[D]

Yeah. So when someone starts doing intermittent fasting, what happens to our bodies?

[A]

So what happens is your body will start to shift from burning blood sugar or glucose to using your stored energy. So your fatty tissue during those fasting periods, during your fed state, you'll probably return to using more sugar. Often also as one starts intermittent fasting, depending on how they approach it. But many will have less calorie intake. A person might cut out that meal and not replace that nutrition later in the day. So then you're just reducing your caloric intake. And that can contribute to some early onset of some initial weight loss. So then that makes you feel successful. So by fasting, you know, one might have insulin resistance. So that means that typically with having extra fatty tissue around that doesn't recognize the insulin you're making. And so if your blood sugar is not well managed and creeping up, your body is going to make more insulin because it's not recognizing that signal that that insulin is there. The disadvantage to that is insulin wants to store calories. So it's not managing your blood sugar as well because your body isn't recognizing, but it's still doing its job of storing calories.

[D]

Let me see if I can explain this a little more. Normally, after you eat, your body releases insulin to help move sugar from the blood into your cells, so it can be used for energy. But with insulin resistance, the cells stop responding to the insulin efficiently, so the sugar stays in the bloodstream longer to compensate. The pancreas pumps out more insulin. And then over time, consistently elevated blood sugar can lead to Prediabetes or type 2 diabete, increase the risk of things like heart disease, nerve damage and kidney problems. So creeping up basically means blood sugar levels are gradually rising beyond what the body can comfortably regulate.

[A]

So if intermittent fasting has been shown to reduce insulin levels, and that's their intention, then you might be storing less of your calories in fat. So that happens pretty quickly as far as early in the fasting states, at least as far as what evidence is currently leaning towards. But does that lead to actual blood sugar control? And improved A1Cs is yet to be seen.

[D]

More research is needed, as I like to say.

[A]

Yep.

[D]

And just so we all understand, A1C is a blood test that measures your average blood sugar levels. Looking back over the past two to three months. When researchers talk about whether intermittent fasting improves A1C, they're asking whether it meaningfully improves long term blood sugar control, not just short term changes during the fast. But I'm really curious if intermittent fasting is just a different way to restrict calories than your average diet, or if something special is taking place in the body during intermittent fasting.

[A]

The evidence shows in really good studies, including like randomized controlled trials and everything where they compare people who are doing intermittent fasting and those doing caloric restriction, there really isn't any significant difference in weight loss. There's no significant difference in heart health or other metabolic markers. So really the difference when it comes down to intermittent fasting is if your caloric intake remains the same, you aren't going to see that weight loss, you aren't going to see the metabolic changes or the other reported benefits.

[D]

Okay, interesting. So if you consume the same number of calories during your eating window as you would have had throughout the day, there's no significant difference. Difference. Right.

[A]

Right.

[D]

Now, in terms of the claims around the benefits of intermittent fasting, what does the current medical evidence say and where is it? Still kind of weak.

[A]

So the benefits will show short term studies, and most of those are up to 12 weeks. There are a few that last a year, but they will show some moderate weight loss. But similar to what we see in caloric restriction, there is some improvement in insulin sensitivity, and we have reasonable evidence for that. If we're going to improve insulin sensitivity, maybe we'll see some improvement in prediabetes and metabolic syndrome and type 2 diabetes management and maybe some improvement in LDL or blood pressure, but those changes aren't necessarily significant. Not very clear evidence for living longer, healthier lives in humans. That's mainly in animals. Cancer prevention and mortality is something that can be widely advertised, but there's very limited data. No high quality studies for this. No high quality studies that shows intermittent fasting can prevent cancer nor improve your treatment. Are there studies that are ongoing to look at this? Absolutely, but Nothing convincing currently.

[D]

Dr. Shriver, I want to play you something from our guest Alcavadlo. He talked a bit about intermittent fasting and mental clarity.

[B]

I don't know how much scientific validation there is to what I'm about to say, but anecdotally speaking, I've certainly experienced this and I've talked to other people who've experienced this. It feels like your senses become a little more acute when you haven't eaten for a long time. Your mind just gets a little sharper. Everything seems to get a little sharper.

[D]

Are there studies around the cognitive benefits to add sharpness or focus or anything like that?

[A]

Just like most of the studies for intermittent fasting, there is some possibility of improvement in cognitive benefits, but these are very short term studies and it isn't consistent across populations. The high quality meta analysis data doesn't show any benefit versus a fed state. You know, so fasting is not any better than a fed state. It's very neutral in healthy adults in general. As far as studies go, the best evidence for improving your cognition is still back to exercise and adequate sleep. The studies on this, again, we're just not finding significantly long enough studies or even significant data that fasting in whatever form is super superior to just a healthy diet.

[D]

What's your overall take on the intermittent fasting trend? Do you have like a top level? Here's how I feel about it.

[A]

Yeah, I guess in general, I just don't think the evidence is there. There really isn't evidence to show that it's a better plan than others or that it's really even good for one. If it does meet your needs to improve your health, I think it's okay. But you still have to get back to looking at what, what is the content of what you're eating? There's risk to it too, and so you have to think about that. It can sound great, but it still takes some insight in knowing what you're eating. And what does that do for your body and are you including things that are important to Maintain your muscle mass, your bone density, your basal metabolic rate, and even to live longer, healthier. Because if you're just focusing on that, this is a great plan for weight loss and you're not improving your nutritional choices, you're not gonna see the long term benefits of what we're looking for as we improve our lifestyle, which is improved heart health, less disease, less cancer risk, and living longer and healthier and have more energy. So it's really not a great plan, just isolated by itself.

[D]

I should point out here that both our guests, Jin and Al, talked to me about eating clean. And I have to be honest, I didn't know entirely what that meant from a scientific perspective. So I went to the dictionary and I found that it means consuming food that has been processed or refined as little as possible and is free from additives or other artificial substances. You may have heard this called whole food. So they eat clean, whole foods during their eating windows. The quality of their diet, though, is important. It's likely also a contributing factor to their Overall results. Okay, Dr. Shriver, I want to play one more clip from Jim because she sounds very clinical and official while describing her three goals of intermittent fasting.

[C]

So our first fasting goal is we want to keep insulin low. So of course we don't eat food because insulin is released in response to eating. That's normal. That's physiology. And so we keep insulin low. We don't have anything that tastes sweet or fruity. We're not having, you know, herbal tea that has a sweet flavor profile. Black coffee, bitter flavors do not cause insulin response. So that's why black coffee, plain tea, with the bitter flavor profiles, those are fun. So we're not chewing gum, we're not having breath mints, all of that. Nothing with any kind of sweetener in it.

[D]

Okay, Dr. Shriever, what's your reaction to the first goal?

[A]

Well, any intake is going to trigger insulin. So I think saying that just avoiding sweet or fruity things is going to help keep your insulin low. I mean, that makes it sound like if we just avoid those things, we won't have insulin levels spike. I mean, certainly it's going to be maybe more steady, but I feel like it's overstated and how low. And she really did say that bitter flavors don't trigger insulin. And I, I just, I don't think that's the case. I don't think there's any evidence to support because any intake could really trigger insulin.

[D]

Okay, great. Let's hear Jen's second goal.

[C]

Our second fasting goal is we want to tap into stored fat for fuel. And that is why you're not putting in, you know, butter in your coffee. Because if you're doing that, you're going to be burning the fuel from your coffee cup instead of fuel from your body.

[D]

And what are your thoughts about that?

[A]

She talked about tapping a distort fat for fuel that could take longer in some people than others, depending on your stored glycogen levels. But I think in the fasted state, eventually you're going to use more fat for fuel. That's what some of our weight management medications are good at, helping our metabolic state change too. But I think that's gonna vary among people. And to some extent I think that is true.

[B]

Great.

[D]

And now her third fasting goal.

[C]

Our third fasting goal is we want to have increased autophagy, but it's upregulated when we are fasting clean. And what down regulates autophagy? Well, eating, but especially like if we're eating protein that down regulates autophagy. We want our bodies to be cleaning up all the junky stuff so we're not putting new stuff in. So you want to avoid having pre workouts or bone broth or anything that's going to be a source of protein during the fast.

[D]

She's using a lot of medical terms or, you know, sciencey words here like autophagy. I had to look that one up, by the way. I understand it to mean the process where cells break down and recycle damaged or old parts to keep the body functioning efficiently. Upregulated is another way to say autophagy is increased and downregulated means the process is suppressed. It's also one of those concepts that social media tends to very much oversimplify. A lot of influencers make it sound like fasting instantly flips some kind of mag magical cell reset switch. So is what she's saying here accurate, Dr. Shriver?

[A]

There's no good studies that that happens in humans. And I think the main thing with people really into intermittent fasting is not eating at all in that fasting window. And eating protein will decrease the supposed autophagy that's occurring in there. And so fasting state is really what helps they claim with autophagy, but we don't have evidence for in humans.

[D]

So it seems like generally speaking, she's not saying things that are necessarily incorrect, but maybe brightening them up a bit, adding some saturation to it a little bit.

[A]

Right, right. Being very confident in them and that these are true and valid versus the evidence. That doesn't support them completely or strongly.

[D]

Intermittent fasting is not for everyone. I asked Dr. Shriver, who specifically should avoid it.

[A]

Anyone with a history of eating disorder really should be cautious about considering that, you know, eating disorder. Anyone with diabetes should do it cautiously and not without medical supervision. Anyone who is older, you know, that would be one that I'd be worried about because we want to watch their nutritional intake. Anyone with nutritional deficiencies or otherwise, I'd be really cautious of anyone with lower muscle mass. And back to people with diabetes. Anyone with any signs of insulin resistance should really do that in a supervised fashion.

[D]

Yeah, I mean, that makes total sense. I'm glad you brought up people who have struggled with disordered eating. Only because I lived in San Francisco for a while and intermittent fasting was very popular. But then there was this kind of underlying discussion of, well, are these men who are very into intermittent fasting kind of falling into disordered eating by over controlling their. Their intake?

[A]

Definitely a concern because then they might continue to escalate the time of fasting.

[D]

Yeah. So if a patient asks, you know, they come into your office and they say, hey, I've been seeing these trends online, intermittent fasting. How would you guide that conversation?

[A]

I would get back to the evidence for it and talk about studies looking at intermittent fasting and what the benefit is and why does it work. So intermittent fasting works when people are reducing their calories, and then that leads to weight loss. It can certainly be a plan we can talk about if you're interested, but we still need to look at the big picture for you. So when we are working with patients on weight management, not only are we looking at nutrition, we're looking at physical activity. How much they move throughout the day, what is their exercise like, behavior, how is their mental health? Do they have a history of eating disorder? Otherwise, how is their sleep? Are we looking at medications to help you with weight management? And then how does this fit into that picture? And if you're doing intermittent fasting, it might be really hard to manage side effects of some of the medications we use in weight management. But back to nutrition, we're still going to talk about what is that content of your eating window? And if we're going to focus on physical activity, when is your exercise and when is your nutrition? And how do we make you feel like well enough and have the energy to complete that exercise and do it well and make it effective? That's all still part of the picture. So I think, yeah, it would go back to, does this fit for you, this is why it works. This is why it doesn't work. If you're looking at living longer and healthier, it's back to what is the content of what you're eating, not the time frame that's going to change things for you. If you want to improve your diabetes, maybe we could use it as a tool and do some monitoring and see if it's helpful for you. But we got to watch you closely. Depending on the type of diabetes you have. There are studies ongoing for those with type 1 diabetes. But I definitely would not want a person like that unless they're very good at managing their own blood sugar levels and have good control and without the direction of their doctor to do that on their own.

[D]

You mentioned other medications. Is this something where say I come in and I say, you know, oh, I've heard of these GLP1s that can help me lose weight or I could try this intermittent fasting thing. Would you say that those are options that kind of reflect each other? Are they two tools in your tool belt? How do they compare?

[A]

The best evidence that we can find to correlate the weight loss with the use of weight loss medicines compared to intermittent fasting is fairly challenging because the duration of studies is often different. The best data I can find on intermittent fasting and the various methods within that last up to 12 months. So to summarize just the 12 month data, intermittent fasting produces around 3% at it's honestly 6 to 12 months. So if you want to be specific, alternate day fasting and time restricted eating have about 6% at 12 months. And then phentermine and topiramate has 13%. Naltrexone and bupropion has 10% at 12 months. Semaglutide or wegovy at 2.4 milligrams is 18, 8.3% at 12 months. And that's real world data versus studies. And tirzepatide is 15.3% at 12 months. And again, that's real world data. So the real world data means we're just studying people out in the general population, working with their individual physicians and clinicians and the various education around that nutrition might or an exercise might be different.

[D]

One big takeaway is that intermittent fasting can be effective for weight loss. That is what Those percentages that Dr. Shriever just mentioned are referring to. But its results are generally modest compared to newer medical obesity treatments. In other words, intermittent fasting may help you lose weight, but it's not a magic bullet. And the online hype around intermittent fasting can outpace the actual data. Dr. Shriver also warned that fasting comes with its own set of complications.

[A]

Well, then you have a shorter time frame to get your nutrients in, so you might become vitamin deficient or might struggle to get enough protein in to keep your muscle mass up. Those would be some of the main concerns. Also, depending on how your insulin response is and blood sugar responses, you might run a lower blood sugar and just really feel foggy or not. Well, and also that can disrupt sleep.

[D]

There's also the social media trend. It's promoting this intermittent fasting as a metabolic reset. Another kind of sound science. Y Is there any medical basis for that idea?

[A]

It's more of a marketing phrase really than a medical one. Our body is very highly adapted and doesn't reset in any permanent way. And any benefits will tend to level off as our body adjusts. So it kind of sounds like it's a permanent solution when really it's temporarily our body is going to readjust to the current situation and we can't permanently reset anything. Obesity is a disease, so it takes a lifetime of treatment or monitoring or watching for. You can improve someone's BMI to normal, but your body's gonna tend to go back if you don't keep an eye on it.

[D]

So when would one medically recommend an intermittent fast?

[A]

I think if it makes it easy for one to work on improving their nutrition and you help them create a plan about what does that look like for them and what they typically eat. If that's the best way to help someone, simply get into a process for weight management that might be acceptable to use. But follow up with them closely to see how is it going, how do they feel doing it, how is their hunger responding, how sustainable is it for them? And when it becomes challenging, then how do we move on from there?

[D]

So there are times to recommend it potentially, but it is very personal.

[A]

Yeah, just like anything in weight management, it's very personal discussion on how to help them improve.

[D]

And that discussion, of course, should. Should be with your doctor. That seems like a good note to end on. I think intermittent fasting seems like a very personal decision. And lifestyle. If weight management is your goal, there are better, more researched methods like quality of diet, physical activity and medical options to consider. And there are folks who should definitely avoid trying intermittent fasting altogether. But if you're curious about intermittent fasting, check in with your physician first just to make sure it's the right decision for your health. If you have tried intermittent fasting, let us know about your experience down in the comments and what you thought of this episode. Thanks again to Dr. Jen Shriever for breaking down the science behind intermittent fasting, and to Jen Stevens and Alka Vadlow for sharing their stories and experiences with us. We did it again, y'.

[A]

All.

[D]

We got to the bottom of another popular health trend, and we still have a couple episodes to go. In the next episode, we're going to talk about contrast therapy. You know, going from a sauna to a cold plunge. We used to do this in the Midwest all the time. Claims around contrast therapy are flooding the Internet and popular culture right now. But don't sweat it. We'll get to the bottom of what's real, what's not, and what we're still learning. If you haven't already, please hit the subscribe or Follow button and join us next time on Health versus Hype with the American Medical Association. For more information on all the topics we're covering, visit Amahel Health vs Hype.org that's a M A Health vshype.org Health vs Hype is a production of Ruby Studio from iheartmedia and the American Medical Association. I'm Trace Dominguez. Our producers are Matt Stillo and Pamela Lawrence. Michael DePaul Wilson is our writer. The show is engineered and features original music by Matthew Ernest Filler. Health versus Hype is intended for educational and informational purposes only and does not constitute medical advice, diagnosis or treatment. Always seek the advice of your physician with any questions you may have regarding a medical condition.