Is Fasting Healthy?

by Adam Gould
Is Fasting Healthy?

Fasting is by no means a modern idea. Cultures and religions worldwide feature traditional fasting periods - such as Ramadan in Islam, Lent in Christianity and Yom Kippur and other annual fast days in Judaism – to mention just a few. Alternative medicine practitioners have also long-promoted fasting as a way to cleanse and detoxify the body (though some scientists argue there’s no strong basis for this claim).

Intermittent fasting, and other diet plans that activate our natural ‘starvation mode’, have become some of the most popular weight loss regimes out there, and their rise is set to continue with an increasing body of anecdotal & scientific evidence pointing towards significant changes in weight and body-shape being possible using these methods.

We know that getting balanced nutrition is an important part of a healthy lifestyle, and that ultimately - we need to eat to live. So what effect does not eating, or eating very specific foods, actually have on our biology?


Slim… Fast?

According to the Ramadan Health Guide, your body enters a ‘fasting stage’ around eight hours after you had your last meal. At this stage, with no food to burn, your body starts using glucose stored in your liver and muscles. Once these reserves are exhausted, your body starts burning actual body-fat for energy.

This ‘starvation mode’ is now more commonly referred to as ‘ entering ketosis’ due to the rampant popularity of the KETO diet plan. The difference between intermittent fasting and KETO is that, rather than avoiding any food for long periods of time, with keto you can eat as much fat and protein as you want, as long as your diet is less than 10% carbs. 

Utilising this ‘starvation mode’ is a crucial element of many well-known diets such as Paleo, LCHF, Atkins and (of course) intermittent fasting. Best of all, the first place your body will look for fat to burn into energy is from your belly… 

However, as good as all this may sound to anyone looking to lose a few pounds, losing weight is not healthy for everyone, and you do need to be careful. Fast for too long, or use up too much of your fat reserves, and your body will start burning muscle protein instead… which is not good for your health.

The ketogenic process of energy release also uses up masses of electrolyte minerals & b-vitamins. Running low on these essential nutrients can upset your metabolism and brain chemistry, leading to symptoms such as low-energy levels, brain-fog & headaches to name but a few.

For these reasons the jury is still very much out on the long-term health implications of metabolising energy in this way. What we do know is that, to maintain optimal health while following any fasting regime or highly-specialised diet, it’s absolutely essential to fill the inevitable gaps in your dietary intake and maintain nutritional balance.  

However, as a short term measure, intermittent fasting does look to be an effective and relatively healthy way to lose weight, as it takes advantage of our bodies innate natural ability to use stored fat for energy, rather than trying to force an unnatural change.

Indeed, there’s a growing body of evidence to support the notion that fasting can help with weight loss, with one study suggesting intermittent fasting may reduce body fat by 16 per cent over three to 12 weeks. 

But there are additional ways fasting diets are thought to be good for you too, including:


Too good to be true?

The potential benefits are compelling, but where there are pros there are always cons. The first and most obvious potential symptom of fasting is feeling ravenously hungry... a lot. 

Many people who try fasting diets experience side effects such as fatigue, nausea, dizziness, headaches and insomnia. This is most common as the body transfers from glucose-based energy metabolism to fat-based energy metabolism. These transition effects can be eased using the right nutrition. 

The good news is that if you stick at it, the side effects tend to subside as your body gets used to your new eating regime. 

Critics of fasting point out that while it may work for weight loss because essentially it reduces the number of calories you’re eating, it doesn’t necessarily help you make healthier food choices. Plus if you feel starved or restricted while you’re fasting, there’s a good chance you’ll make up for it by binge eating when you stop.

But all things considered, the general consensus right now is that fasting – if done properly – can be good for you, especially if you’re trying to lose weight. But to do it healthily and reduce your risk of experiencing associated side effects and deficiencies, it needs to be managed well. This means getting proper nutritional support and being aware of how long you can fast for without putting your health at any kind of risk (in other words, not overdoing it!).

Fasting isn’t for everyone, however. So if you need to lose weight but can’t face the idea of not eating for long periods of time – or if you have a medical condition that requires you to eat at regular intervals – take a look at our posts on the science of slimming and supplements for slimming for inspiration. 


Got a supplement for that?

The downside of fasting, and most diets, is that it will inevitably restrict your intake of certain essential nutrients. To what degree this affects your health depends on how intense your regime is, how long you follow it for, and what sort of nutrient reserves you had to start with.

Fat-based energy release (ketosis) uses up b vitamins and electrolyte minerals at a far-increased rate. Shortages in these nutrients can contribute to a variety of symptoms including headaches, low energy, poor concentration and inflammation.

Eating healthy, nutrient-rich foods whenever you can is highly advisable to try and help maintain adequate levels of all those crucial micronutrients and chemicals your body needs to function optimally. 

But, no matter how healthy your diet, if you’re not eating at all for long periods or excluding certain food groups then it’s more than likely you’re not getting enough of certain essential nutrients.  The following supplements may be of particular interest for anyone looking to top-up their nutrition in this way:

  • Magnesium (for electrolyte balance and to combat fatigue)
by Adam Gould