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 what they’re really about. 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. The most common form that people do is when they restrict their daily eating hours. 

Some people may only eat between a window of 10am-6pm and fast for all the other hours of the day, for example. Other people may fast on alternate days. For this post, I’m going to focus on the daily eating hours type of intermittent fasting.

I’ve got some other general posts about why diets don’t work and how weight loss occurs, and I’ll link them here and here and here. I’m against this obsession the media has that says we constantly need to lose weight or have a ‘summer body’. 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. This post is going to be a long one as there’s lots to talk about, so I’ll jump right in.

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.

It 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 your fast begins 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 as the body is trying to make up for the calorie shortfall that you're in via dieting, so it makes you have a larger appetite and so 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 and allows you to feel more hungry. The body is very clever with appetite regulation, which makes a fad diet 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. 

It doesn’t guarantee a calorie deficit:

The only way to lose weight is to be in a calorie deficit and 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 the food. Calorie density means the number of calories in relation to the amount of food. For example, olive oil is a calorie dense food. There is a large number of calories in relation to the amount of olive oil - 1 tablespoon of olive oil has about 100 calories. You could end up consuming more calories than you intended to even when you restrict your eating hours.

Some people may be aiming for a calorie goal while intermittent fasting, but if you already have a calorie goal then there is no need to restrict your eating hours as well. If you're aiming for a set number of calories, then the hours in which you eat them shouldn’t matter. It’s calories in versus calories out that’s more important.

It’s a form of restriction that 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 your fast begins but you feel hungry later on? 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 almost as if food is a prize that you can only eat at certain times.

Following a fasting diet can lead to increased feelings of hunger, 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. 

This form of restriction isn’t helpful as it can lead to binges later on. It can make you feel out of control around food, and all your thoughts may revolve around food and your allowed eating hours. Food should enjoyed guilt free, and restricting your food won't make you feel any better.

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, 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, but the research is limited.

These benefits of intermittent fasting aren’t really conclusive, so it’s not guaranteed you'll see these improvements. Any changes in your health are likely to 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 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 willing 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 and hopefully this blog post has done that. 

I hope you’ve enjoyed this blog post and it’s given you some food for thought. 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