Intermittent fasting is not safe for everyone, dietitian warns

Intermittent fasting is not safe for everyone and should not be adopted without proper medical guidance, a dietitian has warned, as the eating practice surges in popularity through celebrity endorsement and fitness culture. Dr Kanchana Dayanand, Dietitian at Apollo Sugar — Apollo Hospitals in Secunderabad, told HT Lifestyle that while intermittent fasting can improve metabolic health and give the digestive system a rest, several groups face significant risks by following it unsupervised.

People with diabetes, pregnant women, children, teenagers, and those with kidney or heart conditions are among those who should either avoid it entirely or seek medical approval before starting.

Who should not try intermittent fasting?

Dr Dayanand was clear about which groups face the greatest risk. "People with Type 2 diabetes, regular high sugar levels and high HbA1c should follow intermittent fasting only under medical guidance. It is also not recommended for people with Type 1 diabetes," she said. She extended the same caution to people with eating disorders, as well as those who depend on steady nutrition for growth and recovery.

The warning spans several other vulnerable categories. "Pregnant women and lactating mothers are also exempt from following intermittent fasting. Children and teenagers, who need adequate nutrients for bone and muscle strength, are also not advised to follow it. It is also not recommended for people with disease conditions such as renal disorders or cardiac-related concerns," Dr Dayanand added.

Warning signs to watch for

Even for those who do not fall into a high-risk category, intermittent fasting can produce a range of unpleasant side effects if not managed carefully. Dr Dayanand noted that headaches are common during extended fasting periods, while fatigue and dizziness can result from long gaps between meals. Gut-related issues are also a concern — bloating and diarrhoea may arise from consuming too much fibre in a single sitting, while constipation can develop due to reduced fibre intake or insufficient water consumption.

How to start safely

For those who have no underlying conditions and are keen to try intermittent fasting, Dr Dayanand recommends a gradual approach rather than jumping straight into strict fasting windows. The first step is to stop eating between meals and reduce carbohydrate portions, while increasing the nutritional quality of what is eaten. Once the body has adjusted to that rhythm, the next stage is to progress to the 16:8 method — eating within an eight-hour window and fasting for the remaining sixteen hours of the day.

The most widely practised formats include the 16:8 and the 12:12 method, in which fasting and eating hours are split equally. Some individuals, including Bollywood actress Katrina Kaif, take a different approach entirely and simply limit themselves to two meals per day rather than adhering to a fixed time window.

Note: This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a qualified doctor regarding any medical condition.