Know when not to fast

Recognize the conditions and histories where intermittent fasting is the wrong tool.

Why it works

Fasting interacts with physiology and psychology in ways that make it harmful for some people: it can destabilize blood sugar in people on certain medications, can compromise pregnancy and growth, and — most importantly — can reactivate or mask disordered eating by dressing restriction up as wellness. For these groups the mechanism that helps others becomes the mechanism that harms.

How to do it

1. Skip fasting if you are pregnant or breastfeeding, underweight, or still growing.
2. Do not start without medical guidance if you take insulin or glucose-lowering medication.
3. Treat any history of disordered eating as a stop sign — fasting can be a relapse trigger.
4. If fasting makes food anxious, obsessive, or all-or-nothing for you, stop and reassess.

Evidence

Clinical and eating-disorder guidance consistently flags fasting and rigid dietary restriction as risk factors for some populations — this is established clinical caution, not a marginal worry. (clinical)

This is general wellbeing information. Individual risk varies; a clinician or registered dietitian should make the call for your situation.

Common mistake

Pushing through warning signs — dizziness, obsessive food thoughts, bingeing — because fasting is framed as discipline, when those signs mean it’s the wrong approach for you.