Does a gut reset work? An honest look at 3 and 7 day plans

No. A three or seven day gut reset can’t change your gut in any lasting way. Your gut bacteria do shift within a day or two of a big change in diet, but in one well known study they were back where they started two days after it ended. What a short plan can do is start a habit.

That’s worth having. It isn’t what the word reset promises, though.

What is a gut reset supposed to do?

A gut reset is a short eating plan, usually three or seven days long, that claims to rebalance the bacteria in your gut. Most follow the same pattern. Added sugar, refined carbohydrates, alcohol and caffeine come out. Vegetables, wholegrains, beans, fermented foods, water and an early night go in. Some add a powder or a tea, which is usually where the money is made (more on those in should I take a gut health supplement).

Little on that list will hurt most people, and plenty of it lines up with ordinary healthy eating advice. The trouble is the promise attached: that a few days of good behaviour wipes the slate clean.

How fast does your gut change when you change what you eat?

Faster than most people expect, and it changes back about as quickly.

In a study published in Nature in 2014, ten volunteers ate either an entirely animal based diet or an entirely plant based one for five days in a row. Differences in their gut bacteria showed up one day after the new food reached the gut. Two days after the animal based diet ended, their gut bacteria had returned to their original structure.

So your bacteria answer to what you feed them, more or less day by day. That cuts both ways for a reset: you can move things in three days, and undo it by the following Monday. Ten young American adults on extreme diets is a small and unusual group, so I wouldn’t stretch the finding further than that. What it does show is how quickly the gut answers back.

The other half is that you can only steer your gut bacteria so far. Medicines, where and how you live, and things that happened before you were born all play a part. Diet is the piece you control, and it works through what you eat most weeks, not what you ate for three days in January.

Is a gut reset the same as a cleanse?

No, although the marketing often blurs the two. A reset is sold as feeding the good bacteria. A cleanse is sold as flushing something out, and your body has that job covered already: your liver, kidneys, gut and skin remove waste around the clock, and no pill, tea or patch does it better.

When people feel better after a cleanse, the British Dietetic Association puts it down to what tends to come with one, such as drinking less alcohol, sleeping more and moving more, rather than to the product. Cleansing teas that do anything noticeable tend to work as a laxative, which is not without risk.

The good, the bad and the verdict

Here’s how I’d weigh up the two lengths you’ll see sold.

Can a gut reset make bloating worse?

It can, and the fibre jump is usually why. Going from a low fibre week to beans, lentils, wholegrains and a pile of vegetables overnight hands your gut bacteria far more to ferment at once. Any sudden increase in fibre can make symptoms worse, which is why the advice is to build it up gradually and drink plenty of fluid.

If a reset leaves you more bloated on day two, that’s the pace, not something leaving your body. There’s more on this in why more fibre made your bloating worse.

Plans that cut out wheat or dairy carry a second problem. Those foods supply nutrients you need, and dropping them without replacing them is unnecessary and potentially harmful. If you suspect a food disagrees with you, a GP is the place to start, not a seven day plan.

What works better than a reset?

Variety, kept up. The key to a healthy, varied gut microbiome is a varied, balanced diet with different sources of fibre. Food is the main fuel for your gut bacteria, and plant fibre, which you can’t digest yourself, is the part they feed on. That’s the thinking behind counting different plants across a week, which you can try with the 30 plants a week checklist.

The other change that lasts is taking things away. So much of our health is not about what we add in, it is about what we finally remove. On the wards I lived on cereal, packet soup, instant noodles and takeaways washed down with a gin and tonic, and that isn’t a list anyone clears in a weekend.

In fairness to you, one of my own books is called The Real Food Reset. It’s twenty eight days of meals, planned, with the shopping lists written. It doesn’t reset your gut either. It runs for four weeks because the aim is to make the cooking a routine, and a routine needs longer than a weekend to set.

If you’re not sure where your own week should start, the which book quiz asks a few questions and points you somewhere sensible.

When to skip the reset and see a GP

If you feel bloated regularly, or you’ve tried changing your diet and keep feeling bloated, see a GP rather than trying another plan. The same applies to bloating with weight loss you can’t explain, or bloating with blood in your poo. If you have bloating with a swelling or lump in your tummy, ask for an urgent GP appointment or call 111.

A restrictive plan is also a poor idea for anyone who has, or has had, an eating disorder. Talk to your GP before cutting foods out.