A black coffee probably won't.

A white coffee might add two sugars and it definitely will.

If you're thinking of fasting, giving up your morning coffee might be a deal breaker.

The question is, does drinking it break your fast?

And if not, what does?

Is there room for a sweetener or even a splash of milk during your chosen fasting window?

Or is it water all the way?

This is Zoe's Science and Nutrition.

I'm Jonathan Wolff.

Today we ask, what does it take to break a fast?

This episode is part of a limited series to celebrate the launch of the Big IF study.

The world's biggest clinical study to discover how intermittent fasting really affects us.

By inviting our amazing community of citizen scientists to take part in this experiment,

we hope to understand whether intermittent fasting really can improve how we feel,

from our hunger levels to our mood and energy.

To take part for free and discover if intermittent fasting can work for you,

simply go to joinzoe.com slash the big if.

That's THE, B-I-G-I-F, or by the link in the show notes.

The countdown is on, three days until you can join.

We've chosen to speak to Tim's back to today.

Not just because he's one of the top 100 most cited scientists in the world

and has done scientific studies on the subject of fasting, but he's a regular faster himself.

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