Intermittent fasting: Is it worth it?

Intermittent fasting is a method of dieting that is growing in popularity amongst many. It is a practice that has been used for millennia, for both various health benefits and religious beliefs. Intermittent fasting is believed to help gut and immune health, support weight loss and help to maintain lean body mass whilst cutting. In this blog we are going to discuss these topics, answering the questions, what is intermittent fasting? what are it's benefits? and should you be intermittent fasting?

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What is intermittent fasting?

Intermittent fasting involves cycles of voluntary fasting and non fasting, meaning periods of eating vs periods of not eating. There are various methods to intermittent fasting, the most popular being the 5:2 method, time restricted methods and day-to-day fasting. Regardless of what method you choose, the idea of intermittent fasting is to allocate times during the day and week to consume calories, and other times to restrict calorie intake.

The 5:2 method

The 5:2 method divides your 7 day week into 5 days of 'normal' eating and 2 days of fasting. What's important about the 5:2 method is that on the 'non-fasting days' you are maintaining a healthy balanced diet. It is not an excuse to binge and over eat during these days. The 2 days of fasting shouldn't be consecutive to each other, meaning you shouldn't fast two days in a row, but instead make sure there is at least a day of non-fasting in between days of fasting. On the fasting days, you don't necessarily have to restrict yourself to eating nothing!! The idea is you set a significantly lower calorie goal, 500-1000, and stick to this on your fasting days.

Monday - Fasting

Tuesday - Non-fasting

Wednesday - Non-fasting

Thursday - Fasting

Friday - Non-fasting

Saturday - Non-fasting

Sunday - Non-fasting

24 hour method (day-to-day)

The 24 hour method is essentially a more intense version of 5:2. Instead of splitting your week into 5 days of non-fasting and 2 days of fasting, you alternate every 24 hours. So day 1 you will be managing a balanced diet at a reasonable calorie goal, day 2 you are fasting at 500-1000 calories, and this repeats every 24 hours. The same ideas apply to this method as they do to 5:2. On days of non-fasting, you shouldn't use as an excuse to binge and over eat. You should likely aim for your maintenance calories if not a little bit more (if your goal is weight loss).

Day 1- Non-fasting (maintenance calories)

Day 2 - Fasting (500-1000 kcal)

Day 3- Non-fasting (maintenance calories)

Day 4 - Fasting (500-1000 kcal)

Etc...

Time restriction methods

There are various ways of intermittent fasting through time restriction, the most popular of which being the 8:16 method. Unlike the other 2 methods, time restriction divides your day into periods of fasting and non-fasting instead of your week. The 8:16 method gives you 8 hours of non-fasting and 16 hours of fasting. Another difference between this method and the previous 2, is that during periods of fasting, you are restricted to 0 calories. This means no calories at all from food or drink. I.e.. just water, coffee and other 0 calorie liquids. For most people this will look like this,

6pm-10am - Fasting (0 calories)

10am-6pm - Non fasting

Does intermittent fasting work?

So we know what intermittent fasting is, how we can implement it into our day-to-day, but does it work? The advantages of intermittent fasting range from improving gut health to aiding weight loss as well as supporting medical conditions such as diabetes and high blood pressure. In this next section we are going to explore if intermittent fasting actually works and if it's better than just regular dieting.

Intermittent fasting for weight loss

Maybe one of the biggest reasons people consider intermittent fasting is to support their weight loss goals. On paper, calorie restrictive methods will result in weight loss, but we need to consider the behaviour and actual consistency to diets when considering intermittent fasting.

In this section we are going to look at some systematic reviews on recent studies that look at the effects of intermittent fasting and it's effect on weight loss compared to standard calorie restricting diets, and understand why these studies may have shown the results they do.

A 2022 article looked at the Clinical application of intermittent fasting for weight loss and discussed its application to real life. The most important result this article shared is that intermittent fasting showed results on par with normal dieting methods when it came to weight loss. The 3 main forms of fasting we discussed above showed 3-8% weight loss over 8-12 weeks of intermittent fasting. It is important to understand that long-term effects are not accurately represented in this article because studies only lasted this short duration.

As this gives us limited evidence, we analysed a systematic review of 41 articles, addressing 27 studies from 2000-2019 all studying intermittent fasting and weight loss. Of the 27 studies, all showed significant weight loss results, from 0.8%-13%. 12 studies comparing intermittent fasting to calorie restrictions for weight loss found similar results between the two methods.

However, once again, the studies to date do not explore long term differences between fasting and standard calorie restrictive methods.

So to conclude the research analysed above, we know that intermittent fasting works in the short term (8-12 weeks), in terms of weight loss. However, the difference between this and standard restrictive calorie methods is not significant enough to tell whether one is better than the other. My opinion as a coach is that intermittent fast effectively, you likely have to track your calories, just as you would with calorie restrictive methods. So is the added complication of choosing when to eat as well as how much really important? From experience, for some clients intermittent fasting is a better method for weight loss as it encourages you to limit your snacking and binging, however, 8 times out of 10, it is just as effective if not more complicated than just standard flexible dieting techniques.

Intermittent fasting for health management

On top of aiding weight loss programmes, claims of intermittent fasting supporting individuals with certain medical conditions like type 2 diabetes and high blood pressure. Before we discuss the advantages and disadvantages of intermittent fasting for certain medical conditions, understand that Aesthetic Coaching is not a professional health care business. We have reviewed studies and articles and summarised their results to help you gain a better understanding of intermittent fasting. If you have any medical condition that you think might be enhanced or worsened by intermittent fasting, consult a medical professional or doctor first.

Intermittent fasting for Type 2 diabetes

Type 2 diabetes is a condition caused by a lack of insulin production or a lack of response to insulin in the body. Type 2 diabetes is a reversable condition, and dietary methods such as reduced carb/sugar diets are effective for people with type 2 diabetes. But does intermittent fasting help as well? A 2021 article reviewed the effectiveness of professionally supervised intermittent fasting techniques on the effects of type 2 diabetes and found that during fasting periods, insulin resistance and glucose levels were reduced. This concludes that intermittent fasting can be an effective, non-medicinal method to manage type 2 diabetes.

However, the risk of hypoglycaemia (low blood sugar-levels) is possible during lengthened periods of fasting (especially if you are taking meds to reduce blood sugar levels).

Intermittent fasting is generally safe and effective for managing type 2 diabetes, but understanding the risks and effects of fasting is important before you try it.

Intermittent fasting for hypertension

Hypertension, or high blood pressure, is a medical condition that 14.4 million people in the UK suffer from. 9 million of these people have been diagnosed, and 5.4 million are estimated to not know they have high blood pressure. Hypertension can lead to risks of fatal conditions such as heart attacks, strokes and kidney diseases, but, just like type 2 diabetes, it can be completely reversed. Exercise and diet are two of the most effective non-medicinal methods to manage hypertension. So should intermittent fasting be considered a dietary method for managing high blood pressure?

An article from 2022 discussed the differences between low-carbohydrate diets, very-low-carbohydrate diets and intermittent fasting techniques on various health complications including high blood pressure. Despite intermittent fasting being effective for obesity and diabetes, the review concluded that there was limited, if any, benefits for high blood pressure. We recommend following normal dieting techniques, aiming for a low-fat and high fibre diet when managing high blood pressure.