Experts caution that while intermittent fasting can aid weight management, it poses risks for pregnant women, children, diabetics, and those with underlying health issues, urging personalised advice and caution.
Intermittent fasting may suit some adults, but health groups warn that it is not a safe fit for everyone. The main concern is not just skipped meals, but the way longer gaps without food can affect blood sugar, blood pressure, energy levels and the timing of medicines, according to the NHS. That means the same routine that feels manageable for one person can create real problems for another.
Pregnant and breastfeeding women are among those usually advised to avoid it, because their nutritional and fluid needs are higher and more constant. The NHS says children and teenagers should also steer clear, as they are still growing and need regular intake of energy and nutrients.
For people with diabetes, the picture is more complicated. Diabetes UK says fasting can raise the risk of hypoglycaemia, or low blood sugar, and should only be considered with medical advice and monitoring. That caution is especially important for anyone using insulin or medicines that can lower glucose, since meal timing and dose adjustments may need to change.
Eating-disorder charities also warn that restrictive eating patterns can be harmful for anyone with a history of anorexia, bulimia or other disordered eating. Age UK adds that older adults should be careful too, because cutting eating windows can make it harder to meet protein and calorie needs and may increase the risk of unintended weight loss or malnutrition.
Medicines are another issue. The NHS says some drugs need to be taken with food, or at set times that do not sit easily with fasting schedules. Anyone taking regular medication should check with a pharmacist or doctor before changing meal patterns.
The broader message from UK health guidance is simple: intermittent fasting may help some people manage weight, but it is not a universal answer. The NHS treats it as one possible approach to obesity, yet says it should be used cautiously, particularly when there are underlying health conditions. For anyone who feels dizzy, faint, weak or unable to focus while fasting, the safer response is to stop and seek advice rather than push on.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
