Pros and Cons of Intermittent Fasting..Is it Worth it to Try this Latest Diet Trend?
Intermittent fasting is one of the most popular diet trends we see out there today, which is likely why I get asked frequently what my thoughts are on it and whether it's beneficial to try or not.
Because it's still a fairly new diet, there's a lot more research needed to be done to confirm whether intermittent fasting is beneficial or not for humans.
However, in this blog post, we will dive into the possible pros and cons of intermittent fasting and discuss whether or not it's worth it to give it a try.
What is Intermittent Fasting?
Intermittent fasting is a little bit different than most diets we typically see. There are no rules on what type of food and how much you eat, but instead rules on when you eat.
There are different types of intermittent fasting, but with each version, there's a time period where you're able to eat, then a time period where you fast...aka restrict yourself of food (even if you're hungry).
Let's look at the different versions of intermittent fasting before we dive into the pros and cons.
Types of Intermittent Fasting
Potential Benefits of Intermittent Fasting
Heart Health
Intermittent fasting may help lower blood pressure and improve your cholesterol, both of which play a role in your heart health.
A recent review of intermittent fasting discussed three theories as to how it can improve heart health. A reduction in oxidative stress due to a decrease in calorie intake, improvement of our circadian rhythm through the benefits we get from sleep and "fasting" during the night, and our body inducing a ketogenic state while fasting are all theories behind intermittent fasting's impact on potentially improving heart health.
Insulin Sensitivity and Blood Sugar
Insulin sensitivity refers to how well our cells respond to the hormone insulin, which controls our blood sugar. High insulin sensitivity means your body can regulate your blood sugar more effectively, thus decreasing it and lowering your risk for Type 2 Diabetes.
There is limited evidence on how intermittent fasting affects insulin sensitivity in humans. The results are mixed as well, meaning various populations are responding to intermittent fasting differently, so more research is needed.
One review looked at both rodent and human responses to different forms of intermittent fasting. Evidence from rodent models showed that intermittent fasting may improve insulin sensitivity. However, this doesn't automatically mean the same for humans and again, much more research needs to be done with various human populations before we suggest intermittent fasting as a diet for those with insulin resistance or diabetes.
Another intermittent fasting study done on men with pre-diabetes showed that insulin sensitivity did improve, even without weight loss. However, there are some limitations to this study that need to be addressed. The population size for this study was only eight men, so more research needs to be conducted using larger sample sizes and including women.
Another limitation is that the study was only conducted for five weeks, so more studies need to be done with a longer duration period and they should take into consideration the feasibility for participants to adhere to the intermittent fasting regimen, as that could play a role as well.
Brain Function
A review from 2018 associated intermittent fasting with better memory due to reduced oxidative stress. The same review also proposed that intermittent fasting may delay age-related diseases and increase one's lifespan.
One important thing to note from these associated findings is that most of the studies that showed improvement of brain function through intermittent fasting were conducted on animals. Therefore, this conclusion cannot be assumed until more human research is done.
Inflammation
Chronic inflammation is one of the many causes of chronic diseases such as heart disease and diabetes. Intermittent fasting may be linked to reduced inflammation due to an increase of adiponectin, a protein that helps decrease inflammation in the body.
Potential Cons of Intermittent Fasting
Low Energy Levels
Intermittent fasting can cause a lack of energy throughout your day, especially during fasting windows. This review reported that some of the participants experienced coldness, constipation, lack of energy, and headaches when practicing intermittent fasting.
What could likely decrease such a lack of energy? Actually eating and giving your body the fuel it needs to work properly. It's of course always up to you, but if you're an active person or notice the lack of energy is impacting your everyday life, you may want to reconsider doing it.
Increased Preoccupation with Food that Could Cause You to Overeat
Restricting your food intake, whether it's how much you eat or when you eat, can lead to an over-consumption of food.
A review on intermittent fasting found that some participants' thoughts became preoccupied with food. Now, how exactly can restriction lead to binging on food later? Think about it like this:
When our body needs energy, it usually tries to tell us "Hey it's time to eat!" The voice or feelings telling you it's time to eat may get louder and louder until you finally either give in and eat or ignore it to the point where our body gives up telling us it's hungry (not a great thing to let happen).
When we finally give our body something to eat after it's been deprived, it's like "FINALLY!! Let's eat a sh*t ton of food because we don't know when we are going to get this energy again, got to get in as much as possible now."
Thus, your desire to eat typically increases during eating windows that follow a fasting cycle, and that's how overeating may occur.
Metabolism Slows Down
After long periods of fasting, our bodies go into starvation mode..aka survival mode. In survival mode, our body purposely slows our metabolism down as a way to conserve more energy. It also begins to use muscle mass during this time as fuel, meaning it's taking away protein that is stored in your muscle and converting it to energy to be used.
Impact on Women's Hormones
Fasting may have a significant impact on women's health. This potential con of intermittent fasting was a surprise to me, but so important to be aware of!
In a study done on animals, it was shown that fasting reduced the size of female ovaries in rats and significantly impacted their fertility. While rat studies can give us some insight as to how something impacts humans, it's important to look at actual human studies and get further research to confirm.
A review on women who fasted for three consecutive days during the mid-follicular phase did give us a little more insight. The luteinizing hormone, which controls ovulation, was said to be impacted in the women who fasted. Therefore, fasting may impact menstrual cycles, ovulation, and overall, may impact a women's reproductive health.
Impact on Your Social Life
Intermittent fasting can make an impact on the social connections you have, which are a lot more important for health than you may think. Also, food is way more than just fuel! It can be traditional, social, cultural, spiritual, and overall a lot more personal than just calories. Intermittent fasting, which requires eating and fasting windows, can make you miss out on those social experiences that are tied to food.
It's truthfully up to you and how you want to live your life, but if you see that intermittent fasting or any other diet is taking away from the social connection you have with friends, family, coworkers, etc., then you may want to rethink doing it.
Enhances Risk of Disordered Eating
Remember how I said that fasting can lead to overeating? Well, that binge/restriction cycle is a sign of disordered eating. For some people, this doesn't impact their mental health as much. For others, this can be dangerous and lead to a full-blown eating disorder.
Either way, it's a very possible chance that intermittent fasting, or any other style of restriction, can worsen your relationship with food and cause stress in your life, which is why I'm not for any type of dieting.
A Word on Intermittent Fasting and Weight Loss
Notice how I didn't put weight loss in either the pros or cons section? That's because it can be different for everyone.
I'm not denying that intermittent fasting or any other type of diet won't lead to weight loss. In fact, there are several studies, including this one, that show intermittent fasting is just as effective as regular caloric restriction (restriction where timing isn't a factor) in producing weight loss. But that's because you are likely eating less than what your body needs, so naturally, weight loss can occur.
What these studies didn't show? Whether the weight was gained back or not. Did you know that 95% of dieters regain the weight they lost from dieting within 1-5 years? Totally not the dieter's fault, the restriction simply becomes unsustainable because your body's needs are far greater.
Final Thoughts on Intermittent Fasting
So would I recommend intermittent fasting to anyone? No, I personally wouldn't as the cons do outweigh the potential pros in my eyes and at the end of the day I believe there are far better ways to improve your health that don't require dieting.
What can you do instead of dieting?
Focus on what you can add to your life rather than what you have to take away! Think about ways you can use gentle nutrition to help you add foods like whole grains, fruits, and vegetables into the foods you already love.
Stop making yourself restrict foods you love, this only increases your drive to eat that food. Get rid of the rules around food and start focusing internally on how food makes you feel! It's important to eat foods that make you feel good both physically AND emotionally, so being mindful of how foods make you feel internally can help you navigate the two.
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