A giant fork and a blister pack of tablets sitting on chairs at a glass table, facing each other

Imagine your doctor handing you a prescription that just says: eat very little on two days a week. No tablet, no pharmacy queue.

It sounds like a wellness fantasy. But in 2024 a team of researchers actually ran that comparison — a fasting plan against two of the most widely used diabetes medicines — and the fasting plan came out ahead.

So can fasting replace your tablets? The honest answer is more interesting than yes or no: sometimes it can do a similar job, for some people, for a while. And for one group of people, fasting without a plan carries a real risk.

What the evidence shows

Fasting versus tablets. The EARLY trial, run across nine hospitals in China, randomly split 405 adults with newly diagnosed type 2 diabetes and extra weight into three groups: metformin, empagliflozin (two standard diabetes medicines), or a "5:2" plan — two non-consecutive days a week on meal-replacement products, five days of normal eating (Guo et al., JAMA Network Open, 2024).

After 16 weeks, HbA1c — a blood test that reflects your average blood sugar over the past few months — had fallen by 1.9 percentage points in the fasting group, compared with 1.6 on metformin and 1.5 on empagliflozin. The fasting group also lost more weight: about 9.7 kg, against roughly 5.5 to 5.8 kg on the tablets.

Fasting alongside tablets. In the Netherlands, 100 people with type 2 diabetes looked after by their family doctors — all on metformin alone or on diet alone — were randomised to usual care, or to usual care plus a five-day "fasting-mimicking diet" (a very low-calorie, plant-based eating plan) once a month, for a year (van den Burg et al., Diabetologia, 2024). The fasting group needed less medication, and their HbA1c still improved slightly — by 0.3 percentage points more than the usual-care group. Overall blood sugar management improved in 53% of them, against 8% of the others.

A gentler version. In the US, 108 adults with metabolic syndrome — a cluster of raised blood sugar, blood pressure and waistline — squeezed their eating into an 8 to 10-hour window for three months, on top of their usual treatment. HbA1c improved by just 0.1 percentage points more than with usual care alone (Manoogian et al., Annals of Internal Medicine, 2024). Real, but modest.

And the longest fasts? A review of human trials of multi-day water fasting found that blood sugar markers improved in people without diabetes, but stayed unchanged in people with type 1 or type 2 diabetes (Ezpeleta et al., Nutrition Reviews, 2024). More fasting isn't automatically more benefit.

The safety catch

This is the part that matters most. If you take insulin, or a sulfonylurea — a type of tablet that pushes your pancreas to release more insulin — your medicine keeps lowering your blood sugar whether or not you've eaten. A review of fasting studies in diabetes flagged exactly this: a higher risk of hypoglycaemia, blood sugar dropping too low, in people treated with insulin or sulfonylureas (Rajpal & Ismail-Beigi, Diabetes, Obesity and Metabolism, 2020). A later review concluded that time-restricted eating looked safe in type 2 diabetes as long as medication is monitored and adjusted (Uldal et al., Nutrients, 2022).

That's why the trials that went well were supervised. In the Dutch study, nobody was on insulin. When an Austrian team tested fasting in 46 people who were, they gave dietary counselling and continuous glucose monitors, and no severe lows occurred (Obermayer et al., Diabetes Care, 2023). The fasting wasn't the safety net. The plan was.

Why scientists still disagree

The studies are short. EARLY lasted 16 weeks; diabetes lasts decades. In a related trial in people at risk of diabetes, a fasting advantage seen at six months had disappeared by 18 months (Teong et al., Nature Medicine, 2023).

Is it the fasting, or the weight loss? The 5:2 group in EARLY lost almost twice as much weight as the tablet groups. When another trial gave people the same calories with or without a shorter eating window, the window on its own made no difference to weight or blood sugar (Maruthur et al., Annals of Internal Medicine, 2024).

Blood tests, not life events. HbA1c matters, but none of these trials counted heart attacks, kidney problems or eye damage — the things diabetes treatment is ultimately there to prevent.

Who was studied, and who paid. EARLY included only Chinese adults with a recent diagnosis. The Dutch trial was co-funded by L-Nutra, the company behind the fasting-mimicking diet, and its founder, Prof Valter Longo, is a co-author. That isn't a reason to dismiss the result — it's a reason to want it repeated independently.

What you'll hear online

"Fasting reverses type 2 diabetes." It's a hopeful message, and some doctors build their whole approach around it. What the trials show so far is narrower: in people early in their diabetes, structured fasting improved blood sugar and sometimes reduced medication over months. Lasting "reversal" hasn't been tested in large, long trials.

Before believing any fasting claim, it helps to ask five quick questions:

Five questions before you believe a fasting claim

  1. Was this seen in people, or in mice?
  2. How many people, and for how long?
  3. Compared to what?
  4. Did they measure a real outcome, or a number in the blood?
  5. Does the person telling me this sell something related? (Not an accusation — just useful to know.)

For the "fasting beats tablets" headline, the answers are actually quite good: people, about 400 of them, compared with real medicines. The weak spots are question two — sixteen weeks — and question four: a blood test, not a life event.

What would settle it

A trial lasting two years or more, in people with established type 2 diabetes on a range of medicines, comparing fasting with an ordinary diet of the same calories, and counting what really matters — hearts, kidneys, eyes — across many backgrounds. It's expensive and nobody can patent "eat less on Tuesdays", which is exactly why it's a question worth funding.

What you can do

If you live with type 2 diabetes and fasting appeals to you, don't treat it as a swap for your medication — treat it as a plan to make with your doctor. That matters most if you take insulin or a sulfonylurea, where doses may need changing before you start. Your doctor will know what applies to you. We're also preparing a guide: Before you fast on medication: the questions to ask your doctor.

The most striking thing about EARLY isn't that fasting "beat" tablets. It's that the way you eat deserves a seat in the same conversation as the medicines you take.

Curiosity first.

— Dr. Brugal

Voices in the debate

If you'd like to hear the case for fasting from doctors who champion it, these are some of the most influential voices on diabetes and fasting. Their views often go beyond what published human trials have shown so far — which is exactly why it's worth hearing them and checking the studies side by side.

  • Dr Jason Fung — MD, nephrologist (Canada), who sees fasting as a central tool against type 2 diabetes and obesity. Books: The Diabetes Code, The Obesity Code.
  • Prof Andreas Michalsen — MD PhD, internal and nutritional medicine at Charité Berlin, who combines therapeutic fasting with healthy eating for chronic conditions, diabetes included. Book: The Fasting Fix. Penguin Random House
  • Dr Joseph Antoun — MD PhD MPP, CEO of L-Nutra, the company behind the ProLon fasting-mimicking diet. Podcast: Aging Well, episode 192. Episode

For the wider debate, see our series guide: Why scientists still can't agree on fasting — and what would settle it (coming soon). Related: Prediabetic? What fasting can and can't do for you (coming soon).

References

All studies retrieved via PubMed.

  1. Guo L, Xi Y, Jin W, et al. A 5:2 intermittent fasting meal replacement diet and glycemic control for adults with diabetes: the EARLY randomized clinical trial. JAMA Network Open. 2024;7(6):e2416786. Randomised controlled trial, 405 adults with newly diagnosed type 2 diabetes, 16 weeks. doi:10.1001/jamanetworkopen.2024.16786 (PMID 38904963)
  2. van den Burg EL, Schoonakker MP, van Peet PG, et al. Integration of a fasting-mimicking diet programme in primary care for type 2 diabetes reduces the need for medication and improves glycaemic control: a 12-month randomised controlled trial. Diabetologia. 2024;67(7):1245-1259. Randomised controlled trial, 100 adults, 12 months. Co-funded by L-Nutra. doi:10.1007/s00125-024-06137-0 (PMID 38546821)
  3. Manoogian ENC, Wilkinson MJ, O'Neal M, et al. Time-restricted eating in adults with metabolic syndrome: a randomized controlled trial. Annals of Internal Medicine. 2024;177(11):1462-1470. Randomised controlled trial, 108 adults completed, 3 months. doi:10.7326/M24-0859 (PMID 39348690)
  4. Ezpeleta M, Cienfuegos S, Lin S, et al. Efficacy and safety of prolonged water fasting: a narrative review of human trials. Nutrition Reviews. 2024;82(5):664-675. Narrative review of human trials. doi:10.1093/nutrit/nuad081 (PMID 37377031)
  5. Rajpal A, Ismail-Beigi F. Intermittent fasting and 'metabolic switch': effects on metabolic syndrome, prediabetes and type 2 diabetes. Diabetes, Obesity and Metabolism. 2020;22(9):1496-1510. Review. doi:10.1111/dom.14080 (PMID 32372521)
  6. Uldal S, Clemmensen KKB, Persson F, et al. Is time-restricted eating safe in the treatment of type 2 diabetes? — a review of intervention studies. Nutrients. 2022;14(11):2299. Review. doi:10.3390/nu14112299 (PMID 35684097)
  7. Obermayer A, Tripolt NJ, Pferschy PN, et al. Efficacy and safety of intermittent fasting in people with insulin-treated type 2 diabetes (INTERFAST-2) — a randomized controlled trial. Diabetes Care. 2023;46(2):463-468. Randomised controlled trial, 46 adults on insulin, 12 weeks. doi:10.2337/dc22-1622 (PMID 36508320)
  8. Teong XT, Liu K, Vincent AD, et al. Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial. Nature Medicine. 2023;29(4):963-972. Randomised controlled trial, 209 adults, 6 months plus 12-month follow-up. doi:10.1038/s41591-023-02287-7 (PMID 37024596)
  9. Maruthur NM, Pilla SJ, White K, et al. Effect of isocaloric, time-restricted eating on body weight in adults with obesity: a randomized controlled trial. Annals of Internal Medicine. 2024;177(5):549-558. Randomised controlled trial. doi:10.7326/M23-3132 (PMID 38639542)

Awareness content — not medical advice. Always talk to your doctor or pharmacist before making changes.