Screening first Answer the questions below honestly. If any apply to you, select them. This helps identify whether fasting tools are appropriate for your situation.
Screening questions
✓ No flags identified
No specific contraindications identified from your answers. You can use the fasting tools below, but always listen to your body and stop if you feel unwell.
This screening is for informational purposes only and does not constitute medical advice. Only a qualified healthcare professional can assess your individual suitability for fasting.
Intermittent fasting has significant evidence behind it for metabolic health and weight management, but it is not appropriate for everyone. This screening tool identifies clinical contraindications and cautions that should prompt a conversation with a healthcare professional before starting any fasting programme.
Who should not fast without medical supervision
Certain conditions make unsupervised fasting genuinely risky rather than just inadvisable. Type 1 diabetes requires carefully timed insulin administration with meals; extended fasting fundamentally disrupts this balance and can lead to dangerous hypoglycaemia or DKA. Similarly, insulin and sulfonylurea medications actively lower blood glucose — fasting without medication adjustment carries real hypoglycaemia risk.
Pregnancy and breastfeeding impose elevated nutritional demands, and calorie restriction risks insufficient supply for both mother and baby. A history of eating disorders is a particularly important flag: structured fasting regimens can trigger relapse in those with past restrictive eating patterns, even years after recovery.
Conditions requiring a medical check first
Several conditions warrant a GP or dietitian consultation before starting rather than an absolute contraindication. Type 2 diabetes managed with non-insulin medication, chronic kidney disease, recent surgery, and certain cardiac conditions all fall into this category. The concerns are real but manageable with professional guidance rather than requiring complete avoidance.
Worked example and interpretation
A worked example helps translate the fasting safety screening tool maths into a realistic scenario so the user can compare the headline result with a concrete set of inputs.
That matters because a result is easier to trust when the page shows how the same logic behaves in a practical case instead of leaving the formula abstract.
Frequently asked questions
Can I fast with Type 2 diabetes?
Possibly, but it requires medical review first. Many people with Type 2 diabetes respond well to time-restricted eating, but medication — particularly any drugs that lower blood glucose — may need adjustment. Talk to your GP or diabetes nurse before starting.
Is this screening tool a medical assessment?
No. It identifies factors that the scientific literature associates with elevated risk during fasting. A qualified clinician can assess your individual circumstances, current medications, and overall health in a way this tool cannot.
What can change the fasting safety screening tool result?
The fasting safety screening tool result can change when the inputs, the planning assumptions, or the measurement context change. That is why the page is most useful when you read the result alongside the method notes, limitations, and any caution states rather than treating one output as a complete medical or nutrition answer.
