Intermittent Fasting is something that I've been familiar with for years. Even before I heard the term, I was an intermittent faster. I didn't know it; I just preferred to eat when I was hungry, not when the clock told me that it was mealtime.
I've always found it strange that “day jobs” are set up as 9-5 with lunch at noon, and as a culture – in North America, at least – we're trained to eat dinner around 6 or 7 pm with breakfast in the morning. For decades we were taught to eat three meals a day. Some experts would say to eat three meals plus snacks. I don't argue that eating is required for stable blood sugar and has benefits.
My #1 principal when it comes to wellness:
**There is no one-size-fits-all approach to health.**
What is Intermittent Fasting?
Intermittent Fasting is a pattern in which you cycle between periods of eating and not eating. The “not eating” period isn't the regular time between meals. A standard method of Intermittent Fasting is to have an eight hour eating period and a 16-hour fasting period. For example, finishing dinner at 8 pm, skipping breakfast and then eating at noon the next day. That's a 16-hour fast. Then you have between noon at 8 to eat, so “lunch” and dinner.
Some people only eat one meal a day.
Some have full fast days.
Here are some questions about Intermittent Fasting. Note that there are studies that validate claims on all sides and that this is one of those issues for which it's easy to succumb to confirmation bias. That is, if you're looking for studies that show that Intermittent Fasting is unhealthy, you'll find them. If you're looking for evidence that Intermittent Fasting is healthy, you'll find it. I started this post with promotional material for The Fasting Transformation Summit (affiliate link) and then looked for sources to back up their claims.
Don't expect me to do the same for the 5G Summit. That's one kettle of fish that I do not want to wade into with only Google as my guide and with Google and YouTube banning sites and videos that argue dangers. I'm treading lightly there.
1. Is fasting unnatural and unhealthy?
Intermittent fasting seems to have an overall healing effect on the body by stimulating repair and protection mechanisms.
When you sleep, your body is repairing itself. One way is the rest to the systems involved in eating, digestion and waste.
2. Does fasting slow down your metabolism? And what is “metabolism”?
Fasting slows down your metabolism – or does it?
Metabolism is the internal process by which your body expends energy and burns calories. It runs 24/7 to keep your body moving, even when you're at rest or sleeping. The metabolism converts the food and nutrients you consume into the energy your body needs to breathe, circulate blood, grow and repair cells, and everything else it does to survive.
This process works at different intensities in different people. How fast your metabolism works is determined mostly by your genes. (Source: Harvard Health Publishing)
A long-held belief, validated by other research, is that eating a small meal every 3 to 4 hours keeps your metabolism stimulated so you burn more calories in a day. It claims that when you eat large meals with many hours in between, your metabolism slows down between meals. Those small meals act like stoking a fire, which implies that the metabolism isn't working during periods of not eating.
However, research shows that intermittent fasting can have a metabolism-boosting effect as it promotes a state of ketosis and increases growth hormone levels.
According to another article in Harvard Health Publishing, changing the timing of meals, by eating earlier in the day and extending the overnight fast, significantly benefited metabolism even in people who didn't lose a single pound.
Animal studies support the hypothesis that intermittent fasting and restricting the availability of food to the typical nighttime feeding cycle improves metabolic profiles. It also reduces the risk of obesity, obesity-related conditions such as non-alcoholic fatty liver disease, and chronic diseases such as diabetes and cancer. (Source: Intermittent Fasting and Human Metabolic Health in the Journal of the Academy of Nutrition and Dietetics.)
Several studies have also shown that people who snack regularly eat less at mealtime.
My thoughts on the issue:
It depends on the person—no one-size-fits-all.
Your meals don't have to be big. As your body adjusts to intermittent fasting, you might find that you want to eat less. Your appetite might change. Furthermore, if you're eating a “ketogenic diet” – or high fat, high protein, low carb – you feel fuller for longer. Fat fills you up. That's the idea behind “Bulletproof coffee” – put fat in your morning coffee for satiation until the afternoon. So, snacking regularly to eat less at mealtime depends on the type of food and nutrients that you consume.
3. Does fasting cause nutrient deficiencies?
Fasting causes nutrient deficiencies. -Fact or fiction?
If one already has a nutrient-poor diet, eating less food could lead to vitamin deficiency and muscle loss. However, when you fast, you use up significantly fewer nutrients and can retain them for future use.
Make sure that you eat nutrient-dense foods. If you're practicing intermittent fasting along with the keto diet, please don't do what I refer to as “bacon and eggs keto”. Although the carnivore diet exists, humans need a variety of nutrients to thrive. Specialized diets such as carnivore diet could work short term to address health issues, but it's not a long-term solution. Meanwhile, intermittent fasting poses no long term risk.
(And yes, it's possible to eat a ketogenic diet if you're vegetarian or vegan, but it takes more planning and knowledge.)
4. Does fasting cause muscle loss?
Intermittent fasting can cause muscle loss if you don't eat enough protein, and you don't exercise.
One oft-cited study of 12 women and 4 men (American Journal of Clinical Nutrition, 2009) reported that alternate-day fasting for 8 weeks stimulated fat loss on average of 12 lbs while there was no significant loss in muscle mass.
It's not likely that intermittent fasting would cause an eating disorder. However, it *is* possible that a dietary strategy aimed at promoting weight loss would attract those who already struggle with eating disorders.
If you have an eating disorder already, consider IF carefully.
6. “Is Intermittent Fasting right for me?”
Maybe. I don't know you. Try it and see.
Some say that people with ADHD shouldn't intermittent fast – and I know the effects of proper diet on the brain – but I also think that you're your best expert here. I know that my stomach can't handle eating early and that a fatty coffee or smoothie can leave me satiated until mid-afternoon. I also know that nut butter in my morning smoothies sometimes makes me feel queasy.
If you try IF and experience adverse reactions such as mood swings or brain fog, you can keep it going to see if your body recalibrates itself – the body prefers homeostasis and often will adjust – or you can stop.
If you do intend to do intermittent fasting, pay attention to your body and do not do it if you're pregnant.
And it bears repeating: If you decide to try IF, eat a nutrient-dense diet. Fasting and then binging on carbs will NOT end well.