Monica discusses the latest research on intermittent fasting, focusing on time-restricted eating (TRE) and how it may affect women and men differently. She highlights potential benefits like weight loss and improved insulin sensitivity, while also addressing concerns about muscle loss and hormonal impacts.
Learn about the potential benefits, risks, and practical considerations for implementing this popular eating pattern, especially for women.
References:
Safety of 8-h time restricted feeding in adults with obesity - PubMed (nih.gov)
Time-restricted eating: Watching the clock to treat obesity - PubMed (nih.gov)
Nutrition Diva is hosted by Monica Reinagel, MS, LDN. Transcripts are available at Simplecast.
Hello and welcome to the Nutrition Diva podcast. I'm your host, Monica Reinagel, and today we're revisiting a topic that continues to generate a lot of interest and questions from listeners: intermittent fasting. Specifically, we're going to look at how intermittent fasting, or as researchers call it, time-restricted eating (TRE), might affect women differently than men.
I received an email from a long-time listener, Olga, who's been practicing intermittent fasting for about nine months. She writes:
"Although I've lost a bit of weight, I haven't noticed any other health benefits. In fact, I've been sick more often during this time, and it's taken longer for me to recover from viruses. As I've been digging into research, I've noticed that male and female responses to IF seem to differ. How should women approach intermittent fasting to balance health benefits and hormonal well-being?"
Great question, Olga! And your timing couldn't be better. I just attended a session on time-restricted eating at the annual conference hosted by the Academy of Nutrition and Dietetics, where researchers presented some of the latest findings on this topic.
If you're a long-time listener, you might remember that we've talked about intermittent fasting before. But I always want to keep you up to date as new research emerges!
Let's start by quickly reviewing what we mean by intermittent fasting. There are several different approaches, but time-restricted eating seems to be the most popular. And it’s really quite simple because there is really just one rule: You only eat during a specific window of time each day. Even when people don’t consciously try to cut calories, observing an 8 hour eating window leads them to reduce calorie intake by about 350 calories a day, which naturally leads to modest weight loss. Not surprisingly, shorter eating windows (four or six hours) tend to reduce calories even more, resulting in somewhat greater weight loss.
Interestingly, research has shown that when people adopt TRE, they generally don't change what they eat, they just end up eating a bit less of it. Studies have found that the percentage of calories coming from sugar, fat, protein and fiber don’t change that much when people switch to a time-restricted eating pattern.
This idea of effortless calorie reduction is one of the main appeals of TRE. But one of the concerns with any weight management approach is whether people can stick with it long-term. And there’s encouraging news there as well. Multiple studies have found that participants are able and willing to adhere to their assigned eating windows about 6 out of 7 days per week–at least for the length of the study. This suggests that for many people, TRE could be a sustainable approach to weight management.
Studies consistently find that time restricted eating also helps reduce insulin resistance. This is a significant finding, as improved insulin sensitivity is associated with better blood sugar control and reduced risk of type 2 diabetes.
There have also been some concerns about intermittent fasting leading to loss of lean muscle. And to the extent that it leads to weight loss, it is likely to result in the loss of some muscle tissue. But no more or less than you’d see with other methods of weight loss. If avoiding lean muscle loss is a priority, here are three tips:
Another question that often comes up is about the timing of the eating window. While some research suggests that an earlier window (like 8am to 4pm) might be better for glucose control, people generally find it much easier to stick with a later window. And when it comes to long-term health benefits, consistency is key. So, if a later eating window is more sustainable for you, that's likely to be more beneficial in the long run than struggling with an earlier window that you can't maintain. A noon to 8 PM eating window seems to be a sweet spot for many people, balancing metabolic benefits with long-term sustainability.
Now, let's talk about one of Olga's specific concerns: how intermittent fasting might affect women differently than men. One of the studies discussed at the conference looked at the effects of TRE for up to one year, and found no significant changes in sex hormone levels in either males or females.
However, women's hormonal cycles can influence how they respond to fasting. Some women find that TRE is more challenging during certain phases of their menstrual cycle, particularly in the days leading up to menstruation.
And what about Olga's experience of getting sick more often and taking longer to recover? While we can't say for certain that this is related to her fasting practice, I think it’s something to pay attention to. Fasting can be a form of stress on the body. For some people, this stress can be beneficial, leading to improvements in metabolic health. But for others, particularly if the fasting period is too long or if there are other stressors in their life, it might tip the balance in the wrong direction.
Studies looking at TRE generally have a very low rate of adverse events or health issues–in most cases, similar to those in a control group. However, nutrition isn't one-size-fits-all. In virtually any study that shows a given outcome, for example, there’s going to be some subset of subjects who did NOT experience that outcome.
So, if you decide to try something like time restricted eating, it's a good idea to go into your experiment with a clear idea of what outcomes you are hoping to see and how you will evaluate them, so that you can assess whether or not it's worth continuing. Secondly, you'd want to also pay attention if it seems like the experiment may actually be having unintended consequences–such as seeming to lower your resistance to infection–and be prepared to decide that this approach may not be for you.
But if today’s exploration has you thinking that TRE is something you’d like to experiment with, let's talk about some practical considerations.
It's also worth noting that there are some groups who should not practice TRE without close medical supervision. These include children under 12, adults over 75, pregnant women, and people with a history of eating disorders.
Although TRE has shown some benefits on blood glucose regulation, if you are taking any medications to control blood sugar, extended fasting periods could lead to low blood sugar. Be sure to talk with your healthcare provider before implementing any sort of fasting protocol.
Lastly, I want to emphasize that while intermittent fasting can be a useful tool for some people, it's not a magic bullet. The fundamentals of a healthy diet - plenty of vegetables, fruits, whole grains, lean proteins, and healthy fats - are still crucial, regardless of when you eat them.
And if for whatever reason a time restricted eating window is not for you, that's okay too. There are many paths to good health and nutrition.
If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com You can also leave me a message at 443-961-6206
If you’re looking for more support for healthy weight management, please check out the tools and resources that are at weighless.life. where I help people create habits, mindset, and lifestyle that help them weigh less without dieting. That’s at weighless.life
Nutrition Diva is a Quick and Dirty Tips podcast. Our team includes Brannan Goetschius, Nathan Semes, Davina Tomlin, Holly Hutchings, Morgan Christianson and Nathaniel Hoopes.
That's all for this episode. Thanks for listening! I'll see you next week.