Intermittent fasting is an eating plan that switches between fasting and eating on a regular schedule. Research shows that intermittent fasting is a way to manage your weight and prevent- or even reverse – some forms of disease. But how do you do it? And is it helpful in kidney disease?
Firstly though what is intermittent fasting?
Many diets focus on what to eat, but intermittent fasting is all about when you eat.
Intermittent fasting (IF) is a diet regimen that cycles between brief periods of fasting, with either no food or significant calorie reduction, and periods of unrestricted eating.
When you think about it, IF is nothing new.
Our bodies have evolved to be able to go without food for many hours, or even several days or longer. In prehistoric times, before humans learned to farm, they were hunters and gatherers who evolved to survive- and to thrive- for long periods without eating.
Benefits of Intermittent fasting
IF has a great many benefits that go well beyond weight loss. Many things happen during IF that can protect organs against chronic diseases like type 2 diabetes, heart disease, age-related neurodegenerative disorders, autoimmune diseases and cancer.
Some of the known benefits of IF include:
- Reduces inflammation and oxidative stress
- Improves blood sugar control
- Aids weight loss by limiting calorie intake, boosting metabolism and lowering insulin levels
- Increases growth hormone secretion which boosts metabolism, helps with weight loss and increases muscle strength
- Reduces insulin resistance- helps to prevent and treat type 2 diabetes and lowers blood sugar levels
- Lowers blood pressure
- Lowers cholesterol and triglycerides
- Induces cellular repair processes
- May help prevent cancer
- Good for brain health- increases the growth of new nerve cells, improves memory and concentration
- Improves gut health
- Improves immune system function
- May help you live longer
Types of Intermittent fasting
One of my favourite types of IF is time restricted eating (TRE). There are a couple of key reasons why I like it, one because it’s usually the easiest to implement and two because it comes with all the key benefits of IF with some added benefits that come from eating in sync with our circadian rhythm.
TRE isn’t actually new to us at all, it’s something we all do automatically because we ‘fast’ while we sleep. We are just extending the ‘fasting’ part of our day and reducing the ‘eating’ part.
The length of fasting time isn’t universally agreed upon but most of the research leans towards eating between a 6–8-hour window (10 hours at the most) and fasting for 16 to 18 hours overnight (or a minimum of 14 hours). So for example, eating within 6 hours and fasting for 18 hours or eating within 8 hours and fasting for 16 hours.
You can of course adjust the hours to suit you, but it’s better for your metabolism and insulin levels to have finished your evening meal by 6pm if you can.
We have evolved to be in sync with the day/night cycle. Ie. Our circadian rhythm. Our metabolism has adapted to daytime food and night-time sleep. Night-time eating is strongly associated with a higher risk of obesity, diabetes, high blood pressure and heart disease.
Our circadian rhythm particularly influences blood sugar regulation. Glucose tolerance changes during the day showing worse glucose control in the evening and night and better glucose control earlier in the day. This means that the exact same meal will spike our blood glucose more at night compared to in the morning, elevating our insulin levels and resulting in easier weight gain.
Let’s clear up a common misconception…..
In Western culture, it’s a common idea that the daily food intake should be divided into three square meals and indeed the mainstream media message is to eat ‘five to six times a day.’ However, the number of meals is not a universal standard, and the widely held opinion that eating more frequently is better for weight control is not as scientifically well established as many believe.
An extensive study published in 2017 investigated 50,660 adults in the United States and Canada. The results showed that eating one or two meals daily was associated with lower body mass index (BMI) compared with three meals daily. Also, those who had a longer overnight fast also had a lower BMI.
Given that obesity is a major risk factor for CVD, type 2 diabetes, high blood pressure, psychological issues, musculoskeletal conditions, cancer and yes kidney disease, maintaining a healthy weight is key when it comes to treating and preventing these diseases.
Basically, the key message here is that eating three (or four or five or six) times a day is not necessarily the basis of a healthy diet and that eating less often and going without food for a longer period overnight is likely to be more beneficial for your health.
Benefits of intermittent fasting for people with CKD
Let’s take a closer look at some of the benefits of IF in people with CKD.
Obesity is a potent risk factor for the development of kidney disease. It also increases the risk of developing some of the major risk factors for CKD like diabetes and high blood pressure, and has a direct impact on the development of CKD and end-stage renal disease.
IF has been shown to boost metabolism and fat burning while preserving lean body mass (muscle), all of which can aid weight loss.
People with CKD are at a much higher risk of cardiovascular disease (CVD), in fact, people with CKD are more likely to die from CVD than from their kidney disease.
IF improves multiple indicators of cardiovascular health including lowering blood pressure, improving cholesterol levels, lowering glucose and insulin and reducing insulin resistance. In addition, intermittent fasting reduces markers of inflammation and oxidative stress that are associated with atherosclerosis (hardening of the arteries).
CKD is associated with an increase in atherosclerosis which begins in the early stages of kidney disease, not only does it reduce blood flow to the kidneys which contributes to kidney damage, but it also contributes to high blood pressure- another cause of kidney damage.
Diabetes and Metabolic Syndrome
There are several different types of intermittent fasting.
Alternate Day Fasting- perhaps the most restrictive of the IF protocols. The plan alternates fast days (no caloric intake, unlimited non-calorie beverages) with feast days allowing normal dietary intake.
Modified Alternate Day Fasting- involves fast days where individuals consume 25% of their usual intake (approximately 500 kcal for women and 600 kcal for men), alternated with a feast day where individuals are permitted to consume their normal caloric intake.
5:2 Diet- similar to the modified alternate day fast but involves eating normally for five days of the week and cutting calories to 25% of normal intake on two non-consecutive days.
Time restricted Eating (TRE)- refers to when eating is limited to a certain number of hours each day. An example of TRE is eating within an 8-hour period and fasting for the remaining 16 hours.
Which type of Intermittent fasting is the best?
Diabetes is the leading cause of CKD and the number of people with diabetes worldwide continues to increase. Managing blood sugar levels is one of the key treatment strategies to prevent and reduce kidney damage in people with diabetes.
There have been multiple studies on people with pre-diabetes and diabetes that have shown that TRE is able to improve the function of the pancreas, improve insulin sensitivity and to decrease blood sugar levels.
In people with elevated fasting glucose and/or HbA1c, TRE has shown an improvement in glucose levels and a significant reduction in HbA1c, independent of a change in weight.
Inflammation and Oxidative stress
Inflammation and oxidative damage from free radicals are key factors in both the development and the progression of CKD. TRE has been shown to lower blood levels of key inflammatory markers such as CRP, IL-6 and TNF-a as well as decreasing markers of oxidative damage.
This isn’t just beneficial for kidney disease, but all other conditions related to inflammation and oxidative stress including cardiovascular disease, diabetes, and cancer.
When we fast, the cells in the body initiate a cellular ‘waste removal’ process called autophagy. This involves the cells breaking down and metabolising broken and dysfunctional proteins that build up inside cells over time. Think of it like taking out the trash.
Current evidence suggests that autophagy has a great impact on the maintenance of kidney functions. Abnormal autophagy function can induce loss of kidney cells, damage to the kidney tubules and scarring of the kidneys.
Recent advances show that autophagy has an important role in CKD and that patients with CKD have altered autophagy responses. Studies in autoimmune kidney disease have shown that when autophagy activity is upregulated, renal function can be preserved.
More energy for healing
Digestion takes up a lot of our body’s energy. In fact, the digestive system can drain energy needed for healing, repair and general maintenance of the body. When fasting, this energy becomes available again to perform those important actions.
But what if I don’t need to lose weight?
IF has typically been touted in the media as a weight loss strategy so it makes sense that people who don’t want/need to lose weight might think it’s not for them. Hopefully you can now see that the benefits of IF extend way beyond weight loss, it’s a strategy to improve overall metabolic health as well as to prevent and treat chronic diseases.
Studies in normal weight individuals have demonstrated all of the benefits of IF I’ve already discussed without the weight loss, so the health benefits don’t come from weight loss alone. This also shows that provided you maintain an adequate caloric intake; IF can be implemented without any associated weight loss.
How to start Time Restricted Eating?
Before starting TRE it is recommended to first discuss this with your healthcare practitioner to evaluate whether it’s appropriate for you.
When you start and end your fast is up to you, you can set the hours to suit you and your routine, but it is better for your metabolism and insulin levels to finish your evening meal as early as possible (at least by 6pm if you can).
One thing to be aware of is that it does take your body a little while to get used to this new eating plan and you might struggle with feeling hungry or ‘hangry’ or lack some energy while fasting to begin with. Rest assured this is only temporary, our bodies quickly adapt and in fact when TRE is compared with general across the board calorie restriction, those doing the TRE actually had less hunger and were more satisfied than those who were eating over the whole day.
Remaining hydrated during your fasting period is super important so make sure you keep up your intake of water (adhering to any fluid restriction you may be on). Herbal teas can also be included during the fasting period provided no milk/honey etc is added.
Cautions and Contraindications
IF isn’t appropriate for everyone and it’s important you get the ok from your doctor or naturopath before implementing any big dietary changes.
Those who shouldn’t start IF include women who are pregnant or breastfeeding, children, people with a history of an eating disorder or any form of disordered eating or type 1 diabetics.
Care should be taken by people on diabetic medication and closer monitoring of your blood sugar levels is needed when starting IF as it can improve insulin sensitivity and lower blood sugar levels so doses of medication may need to be altered over time.
So there you have it, a review of the benefits of IF and how it relates to people with CKD. If you’ve found this information helpful please let me know by clicking the ‘SHARE’ button or head over to our Facebook page to leave any questions or comments.