Fasting for health: Hype or healing?

For years, fasting has been making headlines, from social media to medical journals, with bold claims about weight loss, improved health, energy levels, mental clarity, and even prolonged life, but is it really a medical marvel, or just another wellness fad that will disappear over the next few years? 

According to Dr Narisha Sewgoolam, Physician at Mediclinic Pietemaritzburg, the truth lies somewhere in between.

“Fasting is not merely a passing trend, nor is it a miracle ‘quick fix’,” she says. “It’s an ancient practice with modern relevance, especially in the context of rising non-communicable diseases globally and within South Africa.”

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Evolving applications

Defined as the voluntary abstention from food, drink, or both for a specified period, fasting has been practised across various cultures for over a millennia – originally for religious or spiritual reasons.

Today, however, it’s gaining traction for its potential health benefits, especially among people concerned about weight, diabetes and general metabolic health.

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Not just skipping meals

What sets fasting apart from traditional calorie-cutting diets or skipping the odd meal is intention and structure, says Dr Sewgoolam.

“Fasting is practiced with specific timing and goals in mind, whether spiritual, metabolic or behavioural,” she explains.

Intermittent fasting, for example, includes approaches such as the 16:8 method (16 hours of fasting, 8 hours of eating) or the 5:2 model (eating normally five days a week, with two days of reduced calorie intake).

Other types include alternate day fasting, where you eat every second day, and prolonged fasting, which typically lasts 24 to 72 hours under supervision.

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Adapting to structured fasting

Another important distinction is how the body adapts during structured fasting. “Your body starts to run out of its usual energy source, which is glucose from food. To compensate, it begins breaking down stored fat and produces substances called ketones, which it then uses for energy,” explains Dr Sewgoolam.

“This shift to fat-burning doesn’t necessarily occur with standard dieting or skipping meals at random,” she adds.

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Potential benefits and risks

Emerging research supports several potential benefits linked to fasting, particularly in people with pre-diabetes, obesity or metabolic syndrome.

The benefits, according to Dr Sewgoolam, may include:

• Improved insulin sensitivity and glucose control
• Reduced central fat
• Lower inflammation
• Better cholesterol levels

However, she cautions that fasting is not without risks and warns that its rising popularity can result in people overlooking the potential side effects.

“Fatigue, irritability and headaches are common during the initial adaptation phase. Fasting can also affect hormones like cortisol, leptin and ghrelin, which influence mood, impulse control and decision-making.”

Women, in particular, should be cautious before jumping on the fasting bandwagon. “Excessive fasting may impact the hypothalamic-pituitary-gonadal (HPG) axis, which can lead to menstrual irregularities or even amenorrhoea, which is the absence of a period,” Dr Sewgoolam warns.

“It’s also not advised during pregnancy or breastfeeding, when nutritional needs are significantly higher for your baby’s development.”

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Is fasting for you?

While fasting is sometimes recommended by clinicians, Dr Sewgoolam says that your individual health status, goals and risks should all be taken into consideration.

“Like most things, there is no one-size-fits-all solution and your approach to fasting must be clinically tailored, often in combination with dietary guidance, physical activity, and medical therapy.”

Importantly, fasting is not advised for children and adolescents, due to their increased growth and developmental needs.

Furthermore, people with type 1 diabetes or those on insulin or sulphonylureas (an oral medication to treat type 2 diabetes) should only fast under strict medical supervision due to the risk of hypoglycaemia.

Individuals with a history of eating disorders may be vulnerable to relapse, and those with adrenal or thyroid disorders, particularly if not well controlled, could experience worsening of symptoms.

Patients on medications that require food for absorption or to prevent side effects should also be cautious and consult their doctor before attempting any fasting protocol.

While the science around fasting is promising, the medical community still urges caution. “We need more long-term, large-scale studies, especially in diverse populations like South Africa,” continues Dr Sewgoolam.

“The key to fasting lies in individualisation, informed consent, and multidisciplinary support to harness the potential benefits while avoiding harm,” she concludes.