A disclaimer in plain English. I’m obliged to say this and, more importantly, I actually mean it.
Nothing on this site, in the book, the planner, the journal or the emails is medical advice. I’m a fasting enthusiast with a library card, not your doctor.
Please don’t fast at all if you are:
- pregnant or breastfeeding;
- under eighteen;
- significantly underweight (a BMI under 18.5);
- living with an eating disorder now, or have had one in the past;
- living with Type 1 diabetes, unless your specialist team is supervising;
- recovering from a significant illness or surgery;
- living with active Crohn’s, ulcerative colitis, severe gastroparesis or a gastric ulcer;
- having cancer treatment, unless your oncologist has approved it;
- living with cirrhosis or advanced liver disease.
Talk to your doctor first, and fast only with their say-so, if you:
- have Type 2 diabetes and take insulin or a sulfonylurea (gliclazide, glipizide, glimepiride);
- take an SGLT2 tablet (the “-gliflozins”: dapagliflozin, empagliflozin, canagliflozin);
- take a GLP-1 medicine (Ozempic, Wegovy, Mounjaro and the like);
- take blood-pressure tablets, heart-rhythm medication or diuretics (water tablets);
- have a history of gout, or chronic kidney disease;
- are over seventy and fasting for the first time;
- take long-term steroids, or any medicine you’ve been told to take with food.
Have a proper conversation with someone whose job it is to know your particular body. The same goes if you take any prescription medication at all: some of them want food, some don’t, and your GP or pharmacist will know which. Never stop or change a prescribed medicine because of anything you read here.
Salt substitutes and potassium
Don’t use LoSalt or any potassium supplement without asking your doctor first if you have kidney disease, or take blood-pressure or heart tablets that hold on to potassium: ACE inhibitors (the “-prils”), ARBs (the “-sartans”), spironolactone, eplerenone or amiloride.
When to stop a fast
Discomfort is normal. Distress is not. Stop and eat something gentle if you feel faint or very dizzy, get palpitations, a severe headache that salt and water don’t fix, vomiting, confusion, cramps that salt and water don’t settle, or any numbness, vision change, slurred speech or one-sided weakness. Chest pain or any of those last symptoms need urgent medical help, fast or no fast. If you call for help, tell them you’ve been fasting. When in doubt, eat. There are no medals.
If you have diabetes, take insulin or a sulfonylurea, and feel shaky, sweaty or confused, treat it as a hypo: 15 to 20g of fast-acting sugar (a small glass of fruit juice, or four or five glucose tablets), then follow your diabetes team’s hypo plan.
For everyone else: fasting is one of the safest things in the cupboard when it’s done sensibly. The book spells out what sensibly looks like.
Greg x
