Eight women trying for a baby spent a week on broth and juice in a Berlin fasting trial. All of them were tired, half found it hard, and the trial itself closed early without saying whether it helps

Fertility treatment asks a lot of waiting. You wait for a cycle, for a scan, for a phone call. So it isn't hard to see the pull of something you can do yourself, at home, starting Monday. Fasting is one of the things people try, and a team at Charité, Berlin's university hospital, and the Immanuel Hospital set out to test it properly: a randomised trial of a medically supervised fast for women who had not been able to conceive. A paper published on 9 October 2026 in BMC Women's Health reports one part of that work. It is the part where the women describe what the week was like.

The fast was the kind German clinics have offered for decades. No solid food for seven days, with the option of going on to ten. Each day the women had vegetable juices and broths adding up to no more than 300 calories, and were told to drink two to three litres of water or herbal tea. They did it at home, around their jobs, with a dietitian phoning at least once before the fast and twice during it, and on call if something went wrong. Women aged 25 to 45 with a body mass index between 20 and 40 could join; anyone with a past or present eating disorder or a serious medical condition could not.

Eighteen women were assigned to the fasting group and 13 started the fast. Ten agreed to be contacted for an interview and eight gave one, online, within five weeks of finishing. They were between 30 and 44. All but one had a university degree. Two already had children. Some had been through several rounds of IVF and were done with it, some had decided against it, some were still making up their minds. For six of the eight, this was the first fast of their lives.

Seven of the eight got through the full seven days. The eighth stopped after six, and not because she was struggling: she had a work meeting coming up and didn't trust her concentration. Nobody took up the offer of going past a week.

The good parts will sound familiar to anyone who has read about fasting. Women described feeling light, alert and oddly calm. 'I really had, like, a razor-sharp mind,' said one, who was 44 and on her second fast. 'I didn't forget anything.' Another, 39, said her mood usually swings and she reacts strongly to things that annoy her, and that week it was 'much more balanced'. With no meals to shop for or cook, several found they had time to walk, rest and think.

The hard parts were just as consistent. Every one of the eight reported fatigue. Most had cravings, which came more often than plain hunger. The broths and juices were called tasteless and monotonous. Low and wobbly moods were the thing women found hardest to manage, and some put it down simply to losing the pleasure of eating. Dinner with other people became a problem: sitting there with a cup of broth made the deprivation worse, so some stayed away, and then minded being alone. Many thought it would have been easier in a group. Half the women said the week was fairly easy. The other half did not. One, aged 32, summed it up as 'a necessary evil'.

What kept them going is the most revealing part. The first reason was the obvious one, the hope that it might help them conceive. 'It was just really motivating to have the feeling, okay, I can actually do something,' said a 41-year-old. But as the days went on a second reason took over: they were in a study and didn't want to let it down. The 44-year-old said she nearly ate on day three, and that if it hadn't been part of a study she would not have lasted the seven days. A first-time faster said that without the dietitian 'I think I would have quit'. The authors are frank that neither of those props would be there for someone trying this at home.

Afterwards, the women did not all end up in the same place. One became pregnant during or after the fast, and took that as proof. Some felt more hopeful about going back to treatment. And some went the other way. A 39-year-old said the week left her 'more relaxed regarding the fact that it might not work out. It will happen or it won't happen.' The researchers suggest that getting through something difficult may have let a few women feel they had tried everything, which can make it easier to stop.

Now the limits, and they are large. This paper does not say whether fasting improves fertility. It was never meant to; that is the job of the trial it sits inside, and the paper says that trial ran into recruitment trouble, was closed early, and will report its results elsewhere. So one pregnancy among eight women tells us nothing either way. Eight interviews is a small number even for this kind of research, and the authors say they did not reach the point where new interviews stop turning up new themes. The five women who started fasting and weren't interviewed may have had a rougher time. Nearly everyone was a university-educated woman in Berlin with a job flexible enough to slow down for a week. And the people asking the questions were not neutral. The paper says some of the team work in fasting medicine and have 'a personal interest' in its benefits. Two of the authors co-founded a fasting academy and sit on the board of Germany's medical association for therapeutic fasting, and one co-founded a fasting company.

There is also a number that doesn't quite match. The paper's summary describes the fast as under 500 calories a day; its methods section says up to 300. Either way it is very little food, for a week, in women who may be about to try for a pregnancy. That is why this was done with screening, a study doctor and a dietitian on the phone, and it is not something the paper suggests anyone should copy on their own.