Why Intermittent Fasting Isn't The Best Diet For You

I’m starting a series in which I look at popular weight loss diets and discuss if they're worth the trouble. We're bombarded from every angle that we need to lose weight or be smaller and I don't agree with it. But if people do want to lose weight, then I want them to be able to do it safely, without the use of a fad diet. 

The first in the series is intermittent fasting. Intermittent fasting is an umbrella term for a diet in which you voluntarily fast for a set period of time. 

Some people may only eat between a certain window of time e.g. 10am-6pm. Other people may fast on alternate days. For this post, I’m going to focus on the daily time restricted eating hours type of intermittent fasting.

So, does intermittent fasting really work for weight loss?

Short answer: yes, but only if you’re in a calorie deficit. It’s important to remember it’s a calorie deficit that leads to weight loss, not the fasting. You can achieve a calorie deficit without restricting your eating hours.

Let’s look more into intermittent fasting and why it might not be all it’s cracked up to be.

Intermittent fasting ignores your own hunger cues:

By restricting the hours in which you eat, it limits your ability to listen to your body. What happens if you eating window stops at 6pm but you feel hungry at 7.00pm? You’ll have to ignore your hunger cues and go hungry until you’re able to eat again. When your eating hours roll around again, you’ll be so hungry that you could overeat which will disrupt the calorie deficit you're trying to achieve. 

The reverse could also happen, depending on how restrictively you're following the diet, what if you're not hungry during your eating hours? You’ll be forced to eat even though you don’t want to as you know you won't be able to eat later. It’s not practical to be eating by the clock and ignoring your own appetite signals.

The feelings of hunger and fullness are controlled by hormones within the body. The main hunger hormone is ghrelin, and this is the one that makes you feel hungry and increases your appetite. 

People that are dieting have higher levels of ghrelin. This is the body is trying to make up for the calorie shortfall that you're in through your diet, so it makes you have a larger appetite and eat more to consume more calories. 

The hormone that promotes fullness and satiety is called leptin and it’s created in fat cells. When you're in a fasted state, leptin decreases which allows you to feel more hungry. The body is very clever with appetite regulation, which makes a diet like this much more difficult to follow.

A time restricted diet isn’t helpful as it doesn’t allow you to listen to your own hunger and fullness cues, instead you're relying on the clock telling you when you can and can't eat. 

Intermittent fasting doesn’t guarantee a calorie deficit:

The only way to lose weight is to be in a calorie deficit but just because you limit your eating hours, it doesn’t guarantee you’ll be in a calorie deficit. 

In theory, if you only have a 6 or 8 hour window to eat then you’re probably not going to consume as much food as you would if you ate at all hours of the day. But it doesn’t account for the calorie density of food or the fact that as you're restricting your eating time you're more likely to overeat.  

Depending on your food choices you can easily over do it, even with 'healthy' food.

Intermittent fasting can damage your relationship with food:

Like every popular weight loss diet, intermittent fasting is a form of unnecessary restriction.This time you're restricting the time in which you have to eat. 

What happens if it's during your fasting time but you feel hungry? What do you do if you’re out socialising and everyone around you is eating but it’s outside of your eating hours? It’s treating food as a 'prize' that you can only enjoy at certain times which only makes you want it more.

Following a fasting diet can lead to increased feelings of hunger, higher risk of binging, and increased food related thoughts. You can also feel tired and confused which can lead to irritability and a bad mood. 

When you restrict things, it makes you want that thing more. So, by restricting your eating hours, it can make you want to eat more in order to make up for the time lost. 

Food should enjoyed guilt free, and restricting your food won't make you feel any better.

What are the benefits of intermittent fasting?

I’m not always such a negative Nancy, so I’ll talk about some good things about intermittent fasting as well.

There are some suggestions that intermittent fasting can reduce your blood pressure and reduce the fats in your blood, which can be good for heart health. There is also the idea that intermittent fasting may help with blood sugar control and improve the bodies stress response.

These benefits of intermittent fasting aren’t really conclusive, so it’s not guaranteed you'll see these improvements. Any changes in your health may be from the weight loss rather than the intermittent fasting itself. Also, these benefits only arise if the diet is maintained in the long term, which can be difficult.

My final thoughts:

I don’t think intermittent fasting is a good diet to follow, it’s not guaranteed to achieve weight loss and it could affect your relationship with food. 

I also heard someone refer to intermittent fasting as 'privileged starvation' and I think that's a really interesting way to look at it. We can be so consumed by wanting to lose weight that we willingly restrict our eating time, while some people don't have that choice and are grateful for whatever food they can get.

But everybody is different and what works for one person won't work for another, so you may feel it’s right for you. It’s important to consider the whole picture when starting a weight loss diet as you'll need to be able to stick to it long term. 

If you want to know what I think the best way to lose weight is, you can find my book here.

I hope you’ve enjoyed this blog post. Let me know if there's any popular diets you want me to write about next!

Bye for now! 👋

References:

IF = intermittent fasting

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7021351/ IF and weight loss

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836017/ IF and weight loss

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143449/ IF benefits

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5371748/ Relationship with food

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5756630/ Ghrelin

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-789X.2006.00270.x Leptin

https://pmc.ncbi.nlm.nih.gov/articles/PMC10953463/ IF benefits