Does Caffeine Suppress Appetite and Disrupt Your Cycle? (Episode 549)

Full Transcript: Episode 549

Lisa Hendrickson-Jack:

This is the Fertility Friday Podcast, episode number 549. In today’s FAMM Research Series, I’m delving into a question that I don’t think should be controversial, but always is: does caffeine suppress appetite? We’re going to be diving into a study that examines this question, and I’m going to be sharing some of the things that I’ve observed over the years working with women — especially paying close attention to what’s happening in their cycles. So without further ado, let’s go ahead and jump right in.

In today’s episode, I’m going through a review study that is looking at caffeine, coffee, and appetite control. There were several things that struck me when I was preparing for this episode. I think one of the things that struck me the most was how little research there is into this question of the effect of caffeine on appetite. There are very few studies that actually look at this question. And as we’ll talk about as we go through the study, the way that they are looking at the question, I would argue, is different to the way that people interact with caffeine in their day-to-day lives.

So why does this question matter? What’s really interesting about the caffeine question is that no one is neutral, in my opinion, about caffeine. The reason why I think it’s generally controversial when you bring up coffee — yet shouldn’t be — is because of individuals and their attachment to coffee. I mean, caffeine is a way of life. It’s certainly one of the most socially acceptable activities — to drink coffee every single day. It’s embedded into our culture. If you look at movies, popular culture, if you just talk to your friends, if you watch any television program whatsoever, if you look at the variety of coffee mugs that say “powered by coffee” and “don’t talk to me until I’ve had my coffee” — it’s deeply embedded. And especially for women, it’s just part of the culture, kind of like wine. Coffee in the morning and wine at night. If you start to question the caffeine part, because it’s so natural and embedded in our culture, it becomes controversial because people get territorial about the coffee.

We’re going to talk about how I think that comes into the research that’s out there and has an impact on what is studied and what questions are asked. The reason I wanted to look specifically at the impact of caffeine on appetite is because one of the things I’ve observed very consistently over the years — and I work primarily with women — is that there’s a trend for women to, whether intentionally or most of the time unintentionally, use coffee or caffeinated beverages as a substitute for meals. I have two main gripes with caffeinated beverages. One is that there is this tendency to have coffee in the morning in lieu of breakfast, or to delay breakfast. Maybe you’re intermittent fasting, following your favorite male influencer who’s talked about this. There’s a tendency to use caffeine to extend that fasting window in the morning so that you either skip breakfast altogether or delay it significantly — and that results in an overall lower consumption of food during the day.

In Real Food for Fertility, we looked at intermittent fasting in a lot of depth. One of the studies I looked at found that even when you skip breakfast, you do tend to eat more at lunch. When they looked at study participants who skipped breakfast, they did have a larger caloric consumption at lunch. But even with that larger intake at lunchtime, the overall intake for the day was still less. When breakfast is completely skipped, what the research showed us is that you’re not making up for it calorically — even though you might be eating a little bit more at lunch and potentially a little bit more at dinner or having a few more snacks.

So that’s one of my first initial gripes with caffeine and caffeinated beverages in women who have hormonal imbalances who are looking to improve their cycle. I always like to qualify this: if your cycle is great and you have no issues — you’re charting and you can see that you’re falling into normal parameters in every area — then we have nothing to talk about related to caffeine, because you’re good to go. But what I find is that when I’m working with clients who do have hormonal imbalances and who are looking to optimize their cycle, when we look at the caffeinated beverages and either lower or wean off of them, we do see the cycle rebound in many areas, and we do see the hormonal imbalances improve. This is why I look at caffeine and talk about it — because of the real-world changes you can see in the menstrual cycle when you clean this up.

Frankly, when I came into this work, I was pretty neutral about caffeine. I thought it was excessive to prohibit or limit it. I wasn’t interested in that part of the conversation. I just didn’t think it would make that big of a difference. But after years and years of working with actual human beings and looking at their menstrual cycles, seeing what happens when you actually remove the daily caffeinated beverage habit, and how it positively impacts overall cycle health — that is the reason it’s still on the table and why I’m willing to delve into it.

There’s a lot of research about caffeine and most of it is positive — about the effects on attention and athletic performance. There’s even some research on its impact on weight loss, which I would argue is at least partly because it does have an impact on appetite and food consumption. But there’s interestingly very limited research specifically on this question of how it affects appetite. I feel like it has something to do with bias — because again, everyone loves their coffee.

So let’s dive into the study itself. In this review study, the researchers did a search and scan to find research papers actually looking at how caffeine affects appetite. What I found really interesting was that they had a really high bar. They were specifically looking for high-quality studies — double-blind, placebo-controlled trials. Many of the studies they selected were done in a controlled environment where participants were either given caffeine or a placebo and then provided with a standardized meal three to four hours later. So they were asking: if I give you caffeine and then provide you with a meal three to four hours later, how much of that meal are you going to consume? Is caffeine impacting how much you’re going to eat?

While this is a high-quality study design — they’re giving people meals, calculating macronutrient content, probably weighing the food, getting a very controlled scientific measure of how caffeine impacts eating — in the real world, that’s not how it works. When women are consuming coffee in the morning, it’s often a habit developed and sustained over many, many years. They’re not being provided with a meal at a specific time. And so the tendency I’ve seen in the real world is that the coffee contributes to the suppression of appetite, which then allows women to potentially delay their breakfast.

Some of you are thinking, “Yeah, but I drink my coffee with my breakfast — I don’t skip it.” And I would still argue that what I’ve observed in the real world is that even when clients do that, they’re arguably eating less at lunch, because the appetite-suppressant effect of the caffeinated beverages is still present.

What did the researchers find? Unsurprisingly, even with the controlled design — where participants were given caffeine and then provided with a meal three to four hours later — the researchers found that caffeine had an impact on macronutrient intake, though it was minimal. They didn’t find a huge impact. They didn’t find that participants were eating dramatically less. But they did consistently find a difference — participants were eating a bit less macronutrient-wise. And when they looked at energy — measured in kilocalories — they did find a reduction in energy intake in the group given caffeinated beverages. So even in this highly controlled environment where participants were actually provided meals, there was still a suppressive effect on appetite.

What I would be really curious to see is a different study design — one that more closely mirrors the real-world patterns of habitual coffee drinkers. But these food studies are very difficult. If you just let people live their lives, you can’t weigh all the food. Either way, I thought it was really interesting that there was a difference, and it was consistent, and that even the researchers acknowledged that this was a widely understudied area. Ultimately for their review, they chose only 12 studies that met their criteria.

So why does this matter? To bring it back to how I’ve found it affects clients: when you’re looking at the menstrual cycle under a microscope and you’re seeing evidence of hormonal imbalances — low progesterone, increased PMS symptoms, short luteal phase, spotting before the period — and when you’re also working with a client who has difficulty sleeping, whether that’s trouble falling asleep, waking up a lot at night, or staying awake for long periods — all these things are connected. And what I’ve found so consistently is that when caffeine is addressed — whether reduced or eliminated — we see improvement.

Reducing is going to help, but there’s a difference between reducing and cutting it out. What I’ve observed — and maybe some of you have too — is that if you stop drinking caffeine altogether for a couple of days, the withdrawal symptoms are real. Headaches, a little bit of irritability, reduced alertness. That whole concept of withdrawal is significant. And from what I’ve seen anecdotally from working with women: when they stop coffee completely, for about a week it’s rough — they feel awful, tired, headachy, hard to get up. But once that initial withdrawal period is over, what I find is that they start to feel better. Energy actually improves. Sleep improves. Appetite increases. They find themselves eating more at breakfast or eating more at lunch. It’s so consistent. And then we see the impact on the menstrual cycle, because the menstrual cycle is really sensitive to how much food we eat.

One of the things Lily and I reinforced in Real Food for Fertility is: coffee is not breakfast. If you’re looking to optimize and balance your menstrual cycles and support normal hormone production, the best thing for a reproductive-age woman is to consume three meals a day with sufficient protein, fat, and carbohydrates. The research indicates that if you’re skipping meals, it’s really hard to get the optimal amount of food — you just can’t stuff yourself enough to make up for that meal. And it has other disruptive effects on hormones. There’s a net benefit to reducing caffeine, even though it’s controversial and even though I know some of you are rolling your eyes.

One thing I’ll say is that caffeine habits are not generally a month long — they’re generally years. When clients tell me “it doesn’t affect me,” these are often clients who’ve been drinking coffee every day, maybe twice or three times a day, for five to ten or even longer years. I would just lovingly say: how do you know? If you’ve literally had a caffeinated beverage every single day for years, how would you know what your sleep quality would be like without it?

Think about it this way: if you were to give up your favorite fruit for a week, nothing would happen. Your mood wouldn’t change, your energy wouldn’t change — nothing. But if you eliminate coffee and you’re a regular coffee drinker, your life is awful for about a week. That is evidence that it’s doing something to your body. Even though there’s research about the positive impacts of coffee on alertness — if you’re waking up feeling groggy and the coffee helps with alertness, is that really optimal for your hormones? Is that really the best setup?

I’m not here to take away anyone’s coffee. I actually really like the smell and taste of coffee — I’ll drink a decaf latte at Starbucks. If your cycles are amazing and you have no issues, we don’t need to talk about caffeine. You’re good. But if you are struggling with hormonal imbalances or negative symptoms that are having a real impact on your life, that’s when I bring this up: have we looked at this area? Let’s do an experiment if you’re open to it.

There’s certainly no one-size-fits-all approach. Research suggests caffeine affects people differently — even just body composition can influence how hunger cues and appetite are impacted. But if you’re looking for an additional edge, you’ve tried a lot of different things, and you’re not seeing the results you want in your cycle, this could be one of the reasons why. And if you’re curious enough to do your own mini caffeine challenge and track your cycles, you’d have the opportunity to see if it could have a positive impact for you.

One last thing for the practitioners listening: it’s really important to be aware of your own biases. If you don’t drink coffee and you’re on a militant hunt to get all your clients off caffeine — that’s not going to work, because it’s not necessarily a problem for everybody. And on the flip side, if you’re a regular caffeine drinker who personally doesn’t feel any negative effects, you might allow that to cloud how you work with clients who are sensitive to it — who it is having a negative impact on — and not look at this area for someone for whom it could be the key that changes their whole cycle. Read the research, understand your biases, and let the cycle data guide the conversation.

If you enjoyed today’s episode and you can think of someone who may benefit from hearing it, the share link is fertilityfriday.com/549. Until next time, be well and happy charting.