The Pro’s and Con’s of Intermittent Fasting

Intermittent fasting has become increasingly popular in recent years, but is it really as beneficial as it seems?

While research indicates that intermittent fasting can effectively promote short-term weight loss and may lower the risk of heart disease and type 2 diabetes, it also comes with potential downsides such as fatigue, headaches, irritability, and even loss of muscle mass.

Let’s explore the pros and cons of intermittent fasting to help you determine if it’s the right choice for you.

What Is Intermittent Fasting

Intermittent fasting focuses primarily on ‘when you eat’ and not necessarily ‘what you eat’.

This can work great for some people who are trying to lose weight but not everyone, and depending on how frequently you fast, and what you eat when you are not fasting there can be health issues that are created by intermittent fasting.

Calories in vs. calories out is the cornerstone in any weight loss phase, so only focusing on when to eat won’t solve the issue of weight loss. 

The expectation is that if you reduce the number of times you eat in a day, you won’t eat the same volume as you normally would.

However, this isn’t the case for everyone. Some people will fast between meals and then gorge themselves to make up for the lack of calories they didn’t consume during fasting hours. 

Without this knowledge people will be needlessly fasting only to consume the same amount of calories they normally would and making no progress. 

So by knowing that you also need to reduce your calorie intake as well as fasting, what types of intermittent fasting are there? 

Types of Intermittent Fasting 

While intermittent fasting can involve just about any period of eating and fasting you choose, the five most common variations on the diet

16/8 Method

The 16/8 method requires you to fast for 16 hours and then eat within an 8-hour window. 

5:2 method

Requires you to eat normally for five days and then restrict calories to 500-600 on two non-consecutive days.

Eat Stop Eat

Fasting for 24 hours once or twice a week.

Alternate-day method

This diet consists of fasting every other day while on fasting days, some people choose to consume a small number of calories (around 500), while others prefer a complete fast.

The Warrior Diet

Fasting for 20 hours each day and eating a large meal at night within a four-hour window.

The Problem With Intermittent Fasting

You will probably notice that only one of these methods actually involves reducing calorie intake as a step. 

I like Dr Peter Attia’s nutritional framework which focuses on the 3 levers that you can pull to help with weight loss.

1. Time restricted eating – this is what we know as intermittent fasting and restricting when we eat.
2. Calorie restriction – this is where we restrict the amount that we eat
3. Dietary restriction – this is where we restrict what we eat, for example no sugar or processed foods

Of the 3 levers, the time restricted eating or intermittent fasting is often the easiest to do as it can just involve skipping breakfast, or fasting 1-2 days a week.

Your first thought might be that with something like the alternate-day method, or the warrior diet, it would be almost impossible to eat the usual amounts of food you otherwise would in a day in such a small time frame.

However, we are not just concerned about the volume of food you are eating, but rather the calories and quality of the food you are consuming.

You don’t want to just eat 1-2 meals a day and then gorge yourself on ultra-processed high calorie foods, you need to focus on nutrient dense quality foods.

This is where Peter Attia’s framework comes into it, ideally of the 3 levers you would be doing at least 2 of them.

That means combining intermittent fasting with either calorie restriction or dietary restrictions, and my choice would be to focus on diet restrictions and make sure you are eating quality whole foods.

*Doing this will most likely also mean you are calorie restricted unless you are eating lots of fats.

Another problem with intermittent fasting is that people may not get enough protein during the day, it is hard to eat a lot of protein at once so most people need three servings a day.

The Pros Of Intermittent Fasting

However, if you stick to your regular daily calorie intake during the times that you are allowed to eat during any of the intermittent fasting methods, you will see some positive results. 

Studies suggest intermittent fasting can be effective for weight management, but this is due to reduced calorie intake and may be hormonal changes that favor fat burning.

It should be noted that other studies failed to find a link between Intermittent Fasting and weight loss. 

Intermittent fasting may enhance insulin sensitivity, potentially mitigating type 2 diabetes risk and helping with blood sugar management.

Chronic inflammation is linked to various diseases. Research suggests Intermittent Fasting might dampen inflammation, contributing to overall health.

Some studies indicate Intermittent fasting may benefit cognitive function and protect against neurodegenerative diseases, though research is still being conducted to confirm.

During fasting, the body engages in a process called autophagy, which cleanses damaged cells and promotes cellular repair.

Who Should Not Do Intermittent Fasting?

Pregnant women should not do intermittent fasting, this is a time to be nourishing the growing baby with a quality diet, and adequate amounts of calories, it is not a time to be focusing on weight loss.

There is evidence that fasting (or food scarcity/ famine) during pregnancy can cause epigenetic changes in the baby which will lead to metabolic problems later in life. This can lead to storing calories more efficiently and easy weight gain.

Low thyroid function is another time I would be cautious of starting intermittent fasting, I know it can be very tempting to try this approach because it is so good for losing weight and a lot of people with low thyroid problems have weight gain.

If you are going to try this approach it is important to track your TSH, T4 and T3 to monitor any negative changes, extra stress can have an impact on the T4 to T3 conversion.

Eating disorders, if you have had a past history of anorexia or bulimia restricting food can sometimes cause these past issues to resurface.

A better approach in this case would be to eat three quality meals a day and if you need help with weight or other health problems then tweaking the macronutrients may give you better results.

It would be best to talk to your doctor or practitioner in this case before trying intermittent fasting.

Children and young teenagers who are growing and usually very active would benefit from more regular meals, and intermittent fasting would have no added benefits for them.

Conclusion 

In conclusion, while intermittent fasting can help with weight loss and offer several health benefits, it is important to note that these benefits are often linked to your diet choices and not your diet timing.

Whether you eat 2500 calories a day progressively over a 24 hour period, or eat 2500 calories a day in a 4 hour period, the results are still the same. 

If you focus on intermittent fasting but also add one of the other two levers of dietary restriction or calorie restriction then you will get good results.

Only those who may be prone to snacking between meals but have a high discipline may feel the benefits of intermittent fasting.

So if you really do want to lose weight and get healthier, consider changing the foods you eat rather than when you eat them.