You’ve probably heard of intermittent fasting before. Several research studies have found significant benefits to it.
According to Health Line, these benefits include: lower insulin levels, weight loss, lower risk of diabetes, lower oxidative stress and inflammation, improved heart health, increased growth of new neurons in the brain, and it may help prevent Alzheimer’s disease.
I’m no scientist but those benefits sound almost too good to be true!
So, how do you practice intermittent fasting?
The most popular way is to not eat for 12 to 18 hours a day each day. This means you could have your last meal at 7 pm and your first meal at 12 pm. From 12 pm to 7 pm, you’re allowed to eat as much as you like. This is the technique I chose.
Other methods include going one or two days without eating 2 times a week.
The preconceived myths you need to dismantle before trying intermittent fasting
1) Your metabolic rate will slow down.
Some people think that because you’re not constantly snacking, your metabolic rate will slow down and you’ll eventually gain weight.
The truth is, not eating for a few more hours than usual will NOT change your metabolic rate. In fact, as I said above, I lost weight during this month of intermittent fasting.
2) You’ll automatically lose weight when you do intermittent fasting.
Just because I lost weight doesn’t mean that you will too. What helped me was that my eating time was limited, so I ended up eating less.
However, some people might eat more during that small time period. It really depends on your total calorie intake.
3) You can eat as much as you want when you stop your fast.
You’ve still got to be careful about what you eat, just like you would when you’re not doing intermittent fasting. If you eat badly in your eating time, then intermittent fasting might not be great for you.
4) Hunger pains are bad for you.
Actually, you don’t have to worry about hunger pains because they won’t do you any harm according to research.
5) You shouldn’t exercise on an empty stomach.
Exercising on an empty stomach is fine, according to experts.
In fact, it might even come with significant health benefits. I felt lighter when I was running in the morning without food and my energy levels were fine.
Research has also suggested that running in the morning is good for your brain.
6) You don’t enjoy your meals as much because you want to eat fast.
Quite the opposite for me. I enjoyed my meals a lot more because I knew it would be a long time before I eat again. I ate more mindfully.
7) You’ll become extremely fit from intermittent fasting.
Intermittent fasting alone won’t cause you to become fit. You’ll need to exercise as well.
Intermittent fasting: What the science says
Intermittent fasting has many benefits but they are often lost on people who only focus on the weight loss aspect.
And yes, it can help you lose weight, but intermittent fasting is about resetting the way you consume food and provide your body with the downtime it needs.
Here are some of the many scientific health benefits of intermittent fasting that you might not know about.
1) Fasting can change the way your body produces cells and releases hormones
When you don’t consume food every hour of the day, your body needs to find reserves of energy – such as fat – to breakdown and process.
In its simplest terms, what you are doing is reprogramming your body to rely on itself to continue to function at a high level, even if just for a little while.
We’ve forgotten that our bodies don’t need to consume calories every day, as long as we have ample supplies of water.
Research has found the following changes can occur when the body undergoes fasting:
1) This study found that fasting causes blood insulin levels to drop, facilitating fat burning.
2) The blood levels of growth hormone may increase, which facilitates fat burning and muscle gain.
3) The body performs important cellular repair processes, such as removing waste material.
4) There are positive changes to genes related to longevity and protection again disease.
2) Weight loss is a benefit of intermittent fasting
Okay, let’s just get this one out of the way up front because it is the number one reason people come to intermittent fasting practices: losing weight.
The entire planet is consumed with weight loss, looking better, feeling better, having smaller thighs, having less belly fat, having less chins. It’s an epidemic of the worst kind.
So yes, intermittent fasting can help you lose weight.
According to research, fasting actually increases your metabolic rate by 3.6-14%, helping you burn more calories.
What’s more, fasting also reduces the amount of food you eat, which reduces the amount of calories consumed.
3) Reduce your chances of developing insulin resistance
When we feed our bodies a constant supply of sugar, carbohydrates, fat, and everything else that goes into us while we mindlessly eat our way through the day, our body doesn’t need to create anything for itself.
When we remove food, even just for a little while, we teach our bodies to again rely on itself for the resources it needs.
Some studies show that people who practice intermittent fasting can reduce their blood sugar levels by several percentage points.
4) Intermittent fasting can reduce inflammation in your body and help reduce symptoms related to inflammatory diseases
Inflammation is one of the leading causes of disease in our bodies, yet we continue to pump ourselves full of anti-inflammatory drugs to try to combat what would otherwise be solved by a change in diet.
Foods such as citrus, broccoli, and anything containing trans fat is going to cause inflammation in our bodies.
Greasy burgers, red meat in general, and sugar all cause inflammation.
When we remove these things from our diet, or eat them far less frequently than we are eating them now, we see a reduction in the amount of inflammation in our bodies.
Not only do people feel better, but they move better, feel less stiff, and have more energy.
Some studies show that intermittent fasting may enhance the body’s resistance to oxidative stress and fight inflammation.
5) Your heart could use the help
Our hearts take a beating on a regular basis. No pun intended.
The amount of work our hearts need to do just to keep us alive is astounding, yet we do very little to keep it healthy.
Intermittent fasting helps reduce the amount of fatty deposits around our hearts, improves circulation, metabolism, and provides a cleaner slate for our hearts to work.
Let’s not forget about improved cholesterol levels, which drastically reduce the risk of heart disease, heart attack and stroke.
Plus, your blood pressure can be greatly reduced when the pressure is taken off your heart through a change in your diet.
6) Fasting improves cellular repair
We accumulate a great deal of waste in our bodies as our organs work to keep us alive.
Kidneys, liver, and our intestines all work overtime to remove harmful waste in our bodies.
But not every ounce of waste is removed. Some waste builds up over time and can cause a great deal of harm, become tumors, or create blockages in vital passageways in our systems.
When we practice intermittent fasting, studies have found that we are rerouting our bodies energy into areas that could use some attention.
While our body is busy breaking down new food and new substances and new waste, the old waste is left behind. Give your body time to break down old waste.
WHAT HAPPENS DURING INTERMITTENT FASTING?
To understand IF, you have to first understand what happens when you eat.
“Insulin is a hormone that’s released when we eat, but it isn’t meant to be released all the time,” Tello says. “Intermittent fasting is simply letting your insulin level go down to basically normal so that you unlock your fat stores. So nobody’s going to lose any weight unless they get that insulin level down. Which is why eating very small meals throughout the day doesn’t really help with weight loss.”
HOW TO GET STARTED
When first trying IF, the transition can be challenging, Mattson admits.
Many fasters report uncomfortable, even painful hunger pangs as they abstain from food. Mattson suggests people take it slow, trying different kinds of IF to see what works with their goals and routine. He advises first narrowing the “feeding window” from an initial unrestricted period down to 12 hours, then 10 hours, then eight hours, before finding a feeding window that is sustainable.
During the first week or two of IF, fasters may notice their stomachs grumbling or feel a sense of hollowness. Some people are exhausted, lightheaded, or shaky from diminished blood sugar on fasting days. Others experience poor concentration, irritability, mood swings, and even dizziness. In particular, people who work in long shifts or with heavy machinery should take more care when fasting to stay hydrated, rested, and alert.
After about a month, people typically feel better and less hungry, says Mattson.
Tello agrees: “The longer you can go between meals, the less hungry you are. I think a lot of people’s hunger levels actually decrease as opposed to the very low calorie diet where you’re constantly feeding yourself small, tiny bits of food. That’s like a tease all day long.”
Mattson encourages fasters to be patient and wait for those side effects to pass.
“A lot of people will say, ‘Well, I tried it. I’m too hungry, I’m irritable, and cannot concentrate,’ but they have to stick with it,” he says. “It is kind of like exercise. If you’ve been out of shape, when you start, it takes a while for your body and brain to adjust. But after you get used to it, you actually feel better. And if you stop doing it, you feel worse.”
To make fasting manageable, Tello suggests an overnight fast, which can more easily fit into people’s routines. Research shows that restricting eating to daytime hours, an approach that aligns eating patterns with circadian rhythms, has been shown to have metabolic and weight loss benefits.
“Nighttime eating is horrible,” Tello explains. “Nighttime snacking is like the worst. Eating at night and then going to bed, that all goes right to fat. That is the surest way to gain weight, and it’s so bad for your blood sugars.”
The Five Stages of Intermittent (and Prolonged) Fasting
KetosisBy 12 hours, you’ve entered the metabolic state called ketosis (Anton et al., Obesity 2018). In this state, your body starts to break down and burn fat.
Some of this fat is used by the liver to produce ketone bodies. Ketone bodies, or ketones, serve as an alternative energy source for your brain cells and cells in other tissues when glucose isn’t readily available. Did you know that your brain uses up some 60% of your glucose when your body is in the resting state? When you are fasting, ketone bodies generated by your liver partly replace glucose as fuel for your brain as well as other organs. This ketone usage by your brain is one of the reasons that fasting is often claimed to promote mental clarity and positive mood – ketones produce less inflammatory products as they are being metabolized than does glucose, and they can even kick-start production of the brain growth factor BDNF!
By 18 hours, you’ve switched to fat-burning mode and are generating significant ketones (Anton et al., Obesity 2018). You can now begin to measure blood ketone levels above your baseline values (for example, around a value of 0.6 to 1.0).
As their level in your bloodstream rises, ketones can act as signaling molecules, similar to hormones, to tell your body to ramp up stress-busting pathways that reduce inflammation and repair damaged DNA for example.
Within 24 hours, your cells are increasingly recycling old components and breaking down misfolded proteins linked to Alzheimer’s and other diseases (Alirezaei et al., Autophagy 2010). This is a process called autophagy.
When your cells can’t or don’t initiate autophagy, bad things happen, including neurodegenerative diseases. Autophagy is an important process for cellular and tissue rejuvenation – it removes damaged cellular components including misfolded proteins. Fasting activates the AMPK signaling pathway and inhibits mTOR activity, which in turn activate autophagy. This only begins to happen naturally, however, when you substantially deplete your glucose stores and your insulin levels begin to drop.
peak growth hormoneBy 48 hours without calories or with very few calories, carbs or protein, your growth hormone level is up to five times as high as when you started your fast (Hartman et al.,1992).
Part of the reason for this is that ketone bodies produced during fasting promote growth hormone secretion, for example in the brain. Ghrelin, the hunger hormone, also promotes growth hormone secretion. Growth hormone helps preserve lean muscle mass and reduces fat tissue accumulation, particularly as we age. It also appears to play a role in mammalian longevity and can promote wound healing and cardiovascular health.
minimum insulinBy 54 hours, your insulin has dropped to its lowest level point since you started fasting and your body is becoming increasingly insulin-sensitive (Klein et al., 1993).
Lowering your insulin levels has a range of health benefits both short term and long term. Lowered insulin levels put a brake on the insulin and mTOR signaling pathways, activating autophagy. Lowered insulin levels can reduce inflammation, make you more insulin sensitive (and/or less insulin resistant, which is especially a good thing if you have a high risk of developing diabetes) and protect you from chronic diseases of aging including cancer.
By 72 hours, your body is breaking down old immune cells and generating new ones (Cheng et al., 2014).
Prolonged fasting reduces circulating IGF-1 levels and PKA activity in various cell populations. IGF-1, or insulin-like growth factor 1, looks a lot like insulin and has growth-promoting effects on almost every cell in the body. IGF-1 activates signaling pathways including the PI3K-Akt pathway that promotes cell survival and growth. PKA can also activate the mTOR pathway (and, of interest, too much caffeine during a fast may promote activation of PKA).
You might see where this is leading – pressing the brakes on IGF-1 and PKA through nutrient restriction and fasting can turn down cellular survival pathways and lead to breakdown and recycling of old cells and proteins. Studies in mice have shown that prolonged fasting (greater than 48 hours), by reducing IGF-1 and PKA, leads to stress resistance, self-renewal and regeneration of hematopoietic or blood cell stem cells. Through this same mechanism, prolonged fasting for 72 hours has been shown to preserve healthy white blood cell or lymphocyte counts in patients undergoing chemotherapy.
How to Succeed With an Intermittent Fasting Protocol
- Food quality: The foods you eat are still important. Try to eat mostly whole, single ingredient foods.
- Calories: Calories still count. Try to eat “normally” during the non-fasting periods, not so much that you compensate for the calories you missed by fasting.
- Consistency: Same as with any other weight loss method, you need to stick with it for an extended period of time if you want it to work.
- Patience: It can take your body some time to adapt to an intermittent fasting protocol. Try to be consistent with your meal schedule and it will get easier.
Most of the popular intermittent fasting protocols also recommend strength training. This is very important if you want to burn mostly body fat while holding on to muscle.
In the beginning, calorie counting is generally not required with intermittent fasting. However, if your weight loss stalls then calorie counting can be a useful tool.