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Fasting: Should we follow a dietary restricted diet?

Updated: Feb 21

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Our nutritionist Anna-maria reviews a few reasons why someone may practice fasting. Please note we are not advocating fasting and fasting is not safe to follow if you have any disordered eating thoughts. We recommend speaking with your GP first and please remember fasting is not a simple quick fix solution.

Why do some people practice fasting?

The daily caloric intake for a sedentary person has noticeably increased throughout history. Humans eat much more processed, salty and sugary food and as such we have seen a rise in diseases such as diabetes, high cholesterol, high blood pressure, obesity, cancer and cardiovascular diseases. Currently researchers are trying to find solutions where an individual can lose weight quickly while at the same time maintain overall health and wellness. Fasting, both consistent (2 to 21 days) or intermittent, is a common way of dieting which has been used over hundreds of years. Some people also practice this type of diet due to their religious belief, as it’s considered a way to “remove the toxins” and the “bad energy” from the body.

Fasting, the mitochondria and the free radicals.

Researchers investigated the effects of fasting and how it can affect the mitochondrial function (1). It seems that fasting has the same effects on the body as exercise, as when working under stress it makes cellular level changes which seem to help in the extension of the lifespan (1). Mitochondria are the body’s “powerhouses” that take glucose and convert it into energy so the cells can function effectively. When mitochondria function poorly they tend to generate free radicals, which can possibly damage the cells. When someone fasts, the cells produce lower levels of glucose and they use other energy sources, such as fatty acids, which are not as readily available sources as glucose is. This procedure might help in replacing the unhealthy mitochondria with healthy ones and in reducing the free radical production in the long term (2).

Fasting and aging.

Overeating can often provoke metabolic comorbidities such as excessive accumulation of visceral fat and insulin resistance (2). Research suggests that following an intermittent or periodic fasting diet could possibly have beneficial effects on health and seems to improve age-related diseases (cardiovascular disease, stroke, diabetes, neurological disorders and cancer) (2, 3). Intermittent fasting improves the mitochondrial health, autophagy and DNA repair by activating signaling pathways inside the cells (2). The results seem to be very promising, although further research is required to prove the benefits of fasting on general health and aging prevention (2).

Fasting and visceral adiposity.

Another study (4) which investigated the effects of dietary restricted diets (calorie restriction, intermittent fasting, very low-calorie diet and alternate day fasting) on health, showed that dietary restriction can reduce the total and visceral adipose mass and at the same time improve the inflammatory cytokines profile. Dietary restriction seems to help in increasing the lifespan by improving the body’s inflammatory and metabolic profile (1, 4). This is a very important finding as when the visceral body fat percentage is high it leads to chronic inflammation, reduces life expectancy and provokes diseases such as hypertension, hyperinsulinemia, glucose intolerance and insulin resistance (4).

This early research suggests that if someone follows a calorie restricted diet or follows intermittent fasting a few times per year, it may help his/her body to get rid of the free radicals, reduce oxidative stress and tummy fat as well as it can have long term positive health effects. However, we also know that consuming antioxidants and following a mediterranean diet can also produce similar results!

If you do try one of the calorie restricted diets – it’s essential to be under the supervision of a registered dietitian, registered nutritionist and your physician as these professionals will know your medical history and help you ensure you practice this diet safely and ensure nutritional adequacy. Keep in mind that when you reduce your daily caloric intake, it’s very important to eat foods high in vitamins, minerals, antioxidants and fibres. Some examples are green leafy vegetables, salads, fruits in combination with balanced meals of carbohydrates, proteins and vegetables. This way you will keep your bodies full of energy while you try to reduce your body weight and at the same time stay healthy. Of course, not every diet is for everyone, so it’s always good to ask the advice of a specialist and check if this is a diet pattern you could follow.

Please remember we are here to help, if you would like to speak to us please complete our nutrition form and we can get back to you shortly.

This article was written by Anna-Maria our sports nutritionist. Anna-Maria is a registered sports nutritionist, (SENr, INDI), with 8 years of experience. Anna-Maria trained at Oxford Brookes University and the National and Kapodistrian University of Athens, Greece. She is also a sports scientist and a Yoga teacher and offers nutrition consultations online.


1. Most, J., Tosti, V., Redman, L. M. and Fontana, L. (2016). Calorie restriction in humans: An update. Ageing Res Rev, (16), 1568-1637.

2. Mattson, M. P., Longo, V. D. and Harvie M. (2016). Impact of intermittent fasting on health and disease processes. Ageing Res Rev, (16), 1568-1637.

3. Al-Regaiey, K. A. (2016). The effects of calorie restriction on aging: a brief review. European Review for Medical and Pharmacological Sciences, 20, 2468 – 2473.

4. Lettieri-Barbato, D., Giovanetti, E. and Aquilano. (2016). Effects of dietary restriction on adipose mass and biomarkers of healthy aging in human. Aging, Online ISSN: 1945 – 4589.

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