The Pros and Cons of Intermittent Fasting

by Dan Maggs

- updated November 25, 2021

Before you start any type of fasting there are some things that you need to consider. There are some Pros and Cons of Intermittent Fasting that you need to know about.

This will help you to decide whether this is the right thing for you to be introducing….. Overall I am massively in favour of fasting, and any of the negatives can be easily managed…. But have a read and decide for yourself.

Table of Contents

The Pro’s

It's easy.

Signposting to the easy way

Just miss a meal. What could be easier than that? Have you ever tried one of those diet plans where you’ve got to eat four, five or six times a day because you’ve got to spread those calories out? 

Well I have and they’re pretty hard to stick to. So, what could be more simple than actually missing a meal? There’s less to cook. There’s less to clean up afterwards. And simple means you’re more likely to stick with it in the long term.

It's cheap.

You’re eating fewer meals so you’re going to be spending less money on food. Saving money in this way means you might want to put more money back into buying better quality ingredients, such as organic vegetables or higher well-fed meat.

It's flexible.

Intermittent fasting is not a one-size-fits-all approach. It can be flexible and it can fit in with your own life and your routines. I typically follow a pattern which is known as 16:8 intermittent fasting, which suits my life best. I fast for 16 hours a day and break that fast around lunch time, and eat within an eight-hour window following that.

Sometimes I eat breakfast, sometimes I only eat one meal a day and sometimes I even do longer fasts. It’s completely up to you and you can start at your own pace too.

If the thought of skipping breakfast scares you, then maybe just eat it a little bit later and gradually ease yourself in. You don’t have to jump into some of the longer fasts right away.

With fasting comes feasting.

This is a picture of a feast.

Fasting has been an important part of many religions for thousands of years. Something which has largely been forgotten in modern Western society. We just tend to stick with the feast days.

So, I’m certainly not saying you should feast every time you eat. However, intermittent fasting can really help you feel a bit less guilty about those foods that you are eating when you occasionally decide to treat yourself. And let’s be honest, for most of us, being able to treat yourself every once in a while is part of living a good and happy life.

Intermittent fasting helps with blood glucose control.

Someone Testing blood ketoned

Intermittent fasting by definition means you’re spending longer in the fasted state which means lower blood glucose levels, lower insulin levels, and improved insulin sensitivity.

This is really getting to the heart of what is causing the epidemics of obesity and type-2 diabetes that we’re experiencing. Lots of people are losing loads of weight using intermittent fasting as a tool and also loads of people are using it to reverse their type-2 diabetes.

Intermittent fasting is muscle sparing.

When people lose weight on a calorie-restricted diet, we tend to find that along with fat we also lose muscle mass. It’s important that we don’t lose muscle mass because it gets harder to build it the older we get. 

Fasting helps us lose weight without losing muscle mass. It’s muscle sparing.

Fasting is the perfect complement to a low-carb or ketogenic diet.

Ying and Yang symbols
Yin and Yang... something clever here...

Do you want to spend longer in that fasted state with lower blood glucose levels, lower insulin levels, and higher fat burning? Then when you do eat, eat low carb. 

You’ll stay in that fat-burning state for longer. They really are the perfect match for each other.

Fasting triggers Autophagy.

place setting with autophagy written on the plate

The Nobel Prize in physiology and medicine in 2016 was awarded to Dr. Ohsumi for his work on Autophagy. Now, auto means self and phagy means to eat. So, Autophagy is literally self eating. 

Autophagy is the body’s way of clearing out dead or unwanted cells to produce newer healthier cells. Fasting is the most effective way to trigger autophagy

Fasting may help prevent Alzheimer's disease.

Image of the human brain

Studies in rats show that intermittent fasting slows the decline of the cognitive impairment side of Alzheimer’s disease. This has now become a really exciting research area in humans. This is not particularly surprising to me because a lot of scientists are now thinking of Alzheimer’s disease as like type-2 diabetes for the brain. 

Overall, we see generally decreased levels of oxidative stress and inflammation in the bodies of people who fast. And those are two of the key drivers of chronic disease in humans. 

Now, before we get into the con side of things, I’ve got a question for you. Do you practice intermittent fasting? And if you do, what do you find works for you? What pattern suits you best? Please let me know in the comments down below.

The Con's

Fasting is not a magic bullet.

My primary focus is about weight loss and not everybody experiences the weight loss benefits of intermittent fasting when they do it on its own. It takes some time to flip the metabolic switch between burning carbohydrates as your primary source of fuel and burning fat as your primary source of fuel. 

Depending on the amount of glycogen you’ve got stored within your body which is a short-term carbohydrate store, if you like, it can take anywhere between 12 and 36 hours to flip that metabolic switch where you start to burn ketones from your stored body fat. 

I’ve seen a lot of people get very frustrated when they don’t experience the weight loss benefits and they go back to their old ways. When all they needed to do was switch to some low-carb meals or fast for a little bit longer.

It can be really difficult for some people to do intermittent fasting.

Yes, I did say earlier that intermittent fasting is easy but it’s said that the hardest thing about intermittent fasting is getting started, and I really think that’s true. 

For some people the very idea of missing a meal can provoke significant anxiety. And it’s really, really difficult to get people to even consider intermittent fasting if it brings them out in a panic attack.

Reward-based over-eating.

Like I said earlier, fasting can be paired with treating yourself every now and again. But fasting can make people very preoccupied with food and it can mean that they have difficulty not overeating when they break a fast.

Reward sign

Fasting can be addictive.

Fasting can feed into the competitive nature of some people. So, if some fasting is good then more fasting must be better. And that simply isn’t true. 

This is really just a short hop away from an eating disorder and might even lead to our next problem.

Nutritional deficiencies.

word cloud of nutritional deficiency

How much fasting is good for you before you start to become deficient in certain nutrients? I hear from a lot of people in the comments who are following the one-meal-a-day pattern of fasting. And don’t get me wrong, there are a lot of people who are out there who are doing that really, really well and really paying attention to their nutritional needs. 

But there’s also a lot of people who don’t really give much thought to the amount of protein their body needs just to meet its minimum daily requirements. And what about the micronutrients? Which are the vitamins and minerals that we need for optimum health?


various medications spilling onto the table

Take this medication three times a day after food. But I only eat twice a day, doctor.

Take this medication first thing in the morning after eating. But I don’t eat breakfast, doctor. 

Okay, you get my point. Usually, we can manage to work around this. However, it might lead you to having an awkward conversation with your doctor who might not be as educated around the topic of intermittent fasting as you are.

Fasting is under researched.

Overall, the main problem is there just hasn’t been that much research done on intermittent fasting yet. Now, of course, the majority of funding for big scientific studies comes from the pharmaceutical industries and also from the food industry and nobody makes any money out of people eating less.

As a result, I can’t really tell you what kind of fasting is going to suit you better based on any particularly hard evidence. Let me give you a quick example; many people, myself included, are quite happy to skip breakfast and fall naturally into a 16:8 pattern of eating. 

But is breakfast the most important meal of the day? And hold on a second before you switch off and say I’m being ridiculous. Just hear me out. 

Our bodies have something called a thermogenic response and this occurs more readily in the mornings. We’re also far more sensitive to the effects of insulin on our bodies in the morning. An effect that rapidly declines through the day. 

And there are some very small studies showing benefits from early time-restricted feeding which is between 8:00 A.M. in the morning and say 2 or 3:00 P.M. in the afternoon. Particularly in people with pre-diabetes.


Hopefully because I’ve made a video and a Blog about the pros and cons of intermittent fasting you’ll realize that I’m overwhelmingly in favor of it. 

I think all the problems are things that can be fairly easily overcome if we just put a little bit of effort in. I really do believe that intermittent fasting is something that most adults should consider integrating into their lives.