Fasting and blood sugar

This page is general information and nothing on it is medical advice. Whether you should fast, and on what medication schedule, is a decision only your own doctor can make with you — before the observance begins.

The counterintuitive part: vrat food is not light

The word 'fast' suggests less food and lower blood sugar. The permitted food list often produces the opposite. Sabudana is close to pure starch. Singhara and arrowroot flour are starch. Potato is starch. Sugar and jaggery appear in almost every vrat sweet, and jaggery is not meaningfully different from sugar in how it behaves.

A plate of sabudana khichdi is about 350 kcal of rapidly digested starch cooked in ghee, with roughly 5 g of protein and almost no fibre to slow it. In glycaemic terms it behaves very differently from the dal and roti it replaced.

What happens to glucose during a long fast

For the first several hours, liver glycogen maintains blood glucose and it stays broadly stable.
Somewhere between twelve and twenty-four hours, glycogen runs low and the liver shifts to making glucose from other substrates, with ketones supplying more of the brain's fuel.
In a person without diabetes this is entirely normal and the glucose level stays within range throughout.
In someone taking insulin or a sulfonylurea, the medication continues lowering glucose regardless of any of this — which is the whole of the risk.

The medication that matters

General information only. Never change a dose yourself — this table exists so you know what to ask your doctor about.
Medicine type	Hypoglycaemia risk when fasting	The question to ask your doctor
Insulin	High	How should the dose and timing change on fasting days?
Sulfonylureas (glimepiride, gliclazide, glibenclamide)	High	Should the dose move to the evening meal, or be reduced?
Metformin	Low	Should the timing shift with the meal pattern?
DPP-4 inhibitors (sitagliptin, vildagliptin)	Low	Usually straightforward — confirm timing.
SGLT2 inhibitors (dapagliflozin, empagliflozin)	Low for hypo, but raises dehydration and ketosis risk	Is this safe during a dry fast in heat?
GLP-1 agonists	Low	Confirm timing and any nausea interaction with a single large meal.

Recognising a hypo

Shaking, sweating, palpitations, sudden hunger, irritability, confusion, blurred vision or weakness. During a fast these are easy to mistake for ordinary fasting discomfort, which is exactly what makes them dangerous.

If you suspect a hypo, treat it immediately with glucose or sugar. Every tradition covered on this site permits breaking a fast in a medical emergency, and Islamic jurisprudence addresses this explicitly. A severe hypo can cause seizures and loss of consciousness; there is nothing devotional about risking one.

If you are fasting with diabetes

Have the conversation before the observance starts, not on day three.
Monitor more often, not less. Checking glucose does not break a fast in mainstream Islamic scholarship, and no Hindu or Jain tradition treats a finger-prick as food.
Build the meal that breaks the fast around protein and vegetables as well as starch — curd, paneer, nuts alongside the sabudana rather than sabudana alone.
Keep glucose or sugar physically with you, every day of the observance.
Do not fast on a day you are already unwell, vomiting or dehydrated.

The best-studied case: Ramadan

Ramadan fasting with diabetes has a substantial medical literature and established risk-stratification guidance that doctors use routinely — patients are categorised by risk and advised accordingly, and many are able to fast safely with an adjusted regimen.

If you are in India or the diaspora and your doctor is unfamiliar with the question, it is a reasonable thing to ask them to look up, because the guidance exists and is specific.

SOURCE·Published vrat traditions + IFCT 2017·figures given as ranges; what is and is not sourced is set out in full on the sources page·REVIEWED JUL 2026

Sources, with dates →

Questions about fasting and blood sugar

Is jaggery better than sugar for a fast?

Not in any way that matters to blood glucose. Jaggery is about 95% carbohydrate and behaves much like sugar. It carries trace minerals that refined sugar does not, which is a real but very small difference.

Does checking blood glucose break a fast?

In mainstream Islamic scholarship a finger-prick test does not invalidate the fast, and no Hindu or Jain tradition treats it as food. If you are unsure, ask the person you would normally ask — but do not stop monitoring out of uncertainty.

Why did my sugar go up during a fast?

Two common reasons. The food that breaks the fast is often a large, rapidly digested starch and sugar load. And a long fast plus poor sleep raises cortisol and insulin resistance, which can push fasting glucose up even without food. If it is persistent, that is a conversation for your doctor.

Other guides

ആരൊക്കെ വ്രതം എടുക്കരുത്The most important page on this site. Fasting is safe for most healthy adults and genuinely unsafe for some people — and every tradition described here has provisions for exactly that.വ്രതത്തിനിടയിലെ ജലാംശംMost of what people blame on hunger during a fast is actually fluid. Here is what is really happening, and what you can do about it inside your own observance.Training while fastingYou can usually keep training through a fast. What has to change is when, how hard, and how honest you are about recovery.Breaking a fastThe paran or iftar meal decides how you sleep, how you feel the next morning and — over a nine-day vrat — whether you finish heavier than you started.Fasting and sleepJagran, a midnight paran, sehri splitting the night — the sleep cost of an observance is usually larger than the food cost, and almost nobody plans for it.Protein during a vratThe permitted food list on most Hindu fasts is starch-dominant by construction. Over nine days that matters, and here is what actually fixes it.Lighter vrat food, same rulesEvery swap on this page stays inside the commonly permitted food list. Nothing here asks you to change what your family observes — only how it is cooked.Sendha namak and electrolytesRock salt is customary on a vrat for religious reasons. It also happens to be the reason some fasting days go better than others, and the no-salt vrats are the ones worth watching.Caffeine and fasting headachesThe mid-morning headache on a vrat day is far more often caffeine withdrawal than hunger — and it is the one problem on this site with a completely free fix.Fasting and medication timingA fast does not change what you need to take. It changes when you can take it, and whether there is food with it — which for some medicines is the whole point.Sehri and iftar nutritionThis page deliberately publishes no timings. It covers what makes a sehri hold you through a long day and what makes an iftar something you can sleep after.Nine days of Navratri without losing muscleA practical plan for anyone who trains, built entirely inside the commonly permitted phalahar list.Fasting and women's healthMost of the long, difficult fasts in India — Karva Chauth, Hartalika Teej, Chhath, Vat Savitri — are kept primarily by women. This page covers what that means physically.

SOURCE·Published vrat traditions + IFCT 2017·observance accounts and food composition·REVIEWED JUL 2026

Practices are described as commonly observed; customs differ by family, region, community and sampradaya, and this site is not an authority on any of them. Food values come from the Indian Food Composition Tables 2017 (ICMR–NIN), the older ICMR–NIN tables, USDA FoodData Central, named composition studies and the shared ThaliFacts dataset, reconciled against Atwater factors on every build. Which source applies to which food is listed per food, and every source carries the date it was last checked. General information only — not medical or religious guidance. Fasting is not safe for everyone, particularly during pregnancy or with diabetes or other conditions. Speak to a doctor first.

The people behind these sites

Follow the build

This site and nine others like it are built and photographed by two people: Amit Sharma — behind the build; Geeta Patel — the poses, demonstrated. New work goes up on Instagram and Facebook before it reaches a page here.

Amit Sharma @amitsharmaofficial Instagram

Geeta Patel @geetapatelnz Instagram

Geeta Patel GeetaPatelYoga Facebook

Following changes nothing here — every page stays open, with no account and no wall.