The more I have been learning about fasting and intermittent fasting, the more convinced I have been about the benefits. However, I remember hearing Dr. Valter Longo mention that he did not support intermittent fasting because of a lack of research to support its safety. So today, I decided to look at the question: Is Intermittent Fasting Bad for You? We will look at how intermittent fasting affects your hormones, at the possible risks associated with intermittent fasting and at how you can ensure you practice intermittent fasting safely.
Intermittent Fasting and Your Hormones
The main mechanism behind how intermittent fasting affects your body is that it reduces the need for your body to produce insulin. When you are intermittent fasting, you are compressing your eating window down to 8 hours or less.
How Eating Produces Insulin
Insulin is an hormone produced by the pancreas. Every time you eat, your body releases insulin to use the sugar (glucose) from the carbohydrates in the food for energy or to store for future use.
The Role of Glucagon
Glucagon is also secreted by the pancreas. When blood sugar levels are low, the pancreas releases glucagon. The effect of glucagon is to release stored glucose. Glucagon also induces the liver to make glucose out of protein. Glucagon stimulates the breakdown of fats and ketone production. Moreover, glucagon appears to regulate appetite and satiety.
However, some newer studies point out that glucagon is neither sufficient nor necessary for ketosis. So, without dwelling too much on the complex hormonal reactions that happen within your body, what I want you to understand is this: fasting helps your body become more insulin sensitive and metabolically flexible.
You will be able to use fats as a source of energy instead of just carbs, you will feel more energetic, you will have fewer cravings, more mental focus and reach your ideal weight without obsessing over food. Read my post Intermittent Fasting Without Keto: Why It Works to learn more about how you can be in ketosis without eating keto.
Fasting and Your Stress Hormones
The main concern in regards to fasting, particularly for those who have thyroid dysfunctions is how fasting stimulates the release of stress hormones like cortisol. Short-term stress is good for your body, as it helps it learn to overcome stress and become more adaptive. It’s like exercise. Exercise stresses your body, but the more you do it, you not only gain strength but the ability to recover from stress. Moreover, cortisol also has some powerful benefits like fat loss and anti-inflammatory effects. Excess cortisol, however, suppresses the immune system and may contribute to insulin resistance and thyroid dysfunction.
Risks Associated With Intermittent Fasting
Sounds good, right? So, is intermittent fasting bad for you? Of course not! Is it associated with some risks? Yes, possibly. The main concern with intermittent fasting is the lack of human studies done on the topic. Most research has been done on animals. However, there is no evidence to suggest that intermittent fasting is harmful.
Possible Risks You Should Understand
The possible risks associated with intermittent fasting are individual, not universal. For example:
- Disordered eating: People who struggle with disordered eating should avoid intermittent fasting as it could trigger eating disorders like binge eating and anorexia.
- Dehydration: Sometimes, people forget to drink when they don’t eat.
- Fatigue: Too few calories for an extended period of time might cause some vitamin and mineral deficiencies and fatigue.
- Stress hormones: Fasting causes the release of some stress hormones like cortisol, which may affect your sleep and your general hormonal function (for example your thyroid hormones). Keep in mind that a certain amount of stress hormone for a short time is healthy. Cortisol helps burn fat and reduces inflammation.
Once you are aware of these risks, you can ensure that you practice intermittent fasting safely. Keep reading for more tips on making sure you are intermittent fasting safely.
Dr. Valter Longo on Intermittent Fasting
In case you don’t know who Dr. Valter Longo is, let me just give you a quick introduction. He is a professor at the University of Southern California who has been researching longevity for over 15 years. He created a 5-day fast called the Fasting Mimicking Diet to increase health and longevity. I share more info on my blog, you can start by reading Modified Fasting: How You Can Benefit From Fasting Without Giving Up Food.
First, Dr. Valter Longo favors the term “time-restricted feeding” over “intermittent fasting”. Second, he acknowledges the metabolic benefits of intermittent fasting (like cholesterol, blood pressure, and cancer risks). However, he questions whether it brings true long term benefits like increasing longevity. Instead, he believes that a daily 12-hour fasting window and the Fasting Mimicking Diet two or three times a year are optimal to improve lifespan.
Intermittent Fasting and Longevity
Despite what Dr. Valter Longo says, research is coming out about the benefits of intermittent fasting on health and longevity. The metabolic switch from glucose-based to ketone-based energy comes with increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity.
How to Practice Intermittent Fasting Safely
To make sure you practice intermittent fasting safely, you need to listen to your body. That is the number one key tip I can give you.
Listening to Your Body
Learning to tune out your body is the main issue that can come with intermittent fasting. After all, you are hungry, but you ignore it. However, with time and practice, you will notice that hunger doesn’t bother you the same way. When you become fat-adapted (using ketones for energy), you feel great even when you are a bit hungry.
At that point, you will start making judgment calls if you notice a difference in the intensity or the effect of your hunger. You might decide to eat when you thought you would be fasting, even if it’s just an avocado.
You will find that your body will react differently at different times. That’s why I can’t emphasize enough that intermittent fasting shouldn’t become about ignoring your body’s cues. Instead, it’s about learning to differentiate between different cues. You may find that at some times during your cycle you crave more carbs. Eat more healthy carbs. Or that you can’t fast, you feel too hungry. Eat!
More Ideas to Make Sure You Fast Safely
Here are a few more tips that I want to share to help you make intermittent fasting the best experience possible:
- If you are new to intermittent fasting, start with a modified fast. I mentioned the Fasting Mimicking Diet already. I recommend this approach to help you become more metabolically flexible before experimenting with intermittent fasting.
- Start slowly. Why not just start with a 12-hour eating window and add in one 24-hour fast each week? Or if you don’t think you can go 24 hours without food, try consuming only 500 calories instead.
- Experiment until you find what works. You may have to try different methods to find the one you like. And, your method of choice may change over time. Read How to Decide Which Intermittent Fasting Method Is Best for You for more tips.
- Don’t expect to quit and maintain your progress. Intermittent fasting is a lifestyle. It’s not a crash diet.
- Don’t feel deprived. This may seem like a weird tip, after all, if you deprive yourself, how can you NOT feel deprived? It’s all about your mindset. The joy of intermittent fasting is that you don’t have to obsess over food and calories. Enjoy that and savor the freedom!
- Eat nutrient-dense foods and drink enough water. Another issue with intermittent fasting comes when people take it as a license to binge eat junk food. No matter how long your eating window is, make sure you use it wisely.
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How Long Should You Fast
I want to address the question of how long you should fast quickly. I say quickly because I don’t really have a black-and-white answer. I mentioned the importance of experimenting to find the right intermittent fasting method for you already. What I do want to add is that some women find if quite beneficial to fast anywhere from 36 hours to a few days. I have never fasted completely for more than 24 hours because I am not ready for that. Not sure I will ever be. It goes to show you that you need to pay attention to how you feel and listen to your body to determine how long you should fast. I am quite happy with the Warrior Diet right now. Even then, at this point, my eating window is frequently longer than 4 hours. Make sure you stay flexible!
Read Why You Should Consider The Warrior Diet for Weight Loss if you are curious.
Is Intermittent Fasting Bad for You? Video
Is Intermittent fasting bad for you? Of course not! Do you have to be aware of some risks to make sure you practice it safely? Absolutely! Avoid intermittent fasting if you struggle with eating disorders. Don’t tune out your body, instead learn to differentiate between different hunger cues and cravings for food. Experiment between different fasting methods to find the best one of your. Stay flexible to adapt as your body adapts. Eat nutritious foods and enjoy the journey!