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Some of the health benefits of fasting kick in when food consumption resumes, animal experiments show.Credit: Getty

It’s not the fasting, it’s the eating

Breaking a fast seems to carry more health benefits than the fasting itself, a study in mice shows. When mice started eating again after 24 hours of fasting, stem cells in the gut appeared to experience a boost in their ability to repair damage to the intestines. But this activation of stem cells came at a price: mice were more likely to develop precancerous polyps in their intestines if they incurred a cancer-causing genetic change during the post-fasting period than if they hadn’t fasted at all. “Regeneration isn’t cost-free,” says stem-cell biologist Emmanuelle Passegué.

Nature | 4 min read

Reference: Nature paper

India mission reveals molten Moon

The first-ever analysis of soil near the Moon’s south pole has found further evidence that the lunar surface melted shortly after it formed. The data come from India’s pioneering Chandrayaan-3 mission, which deployed a rover on the Moon last August that found the soil mainly comprised the mineral ferroan anorthosite. Previous landers have found similar results at other locations, suggesting the composition of the surface is uniform. This supports the theory that the Moon originated from material scattered into space when a large impactor struck the newly formed Earth.

Nature | 4 min read

Reference: Nature paper

Video: How to detect gravitational waves

Current techniques to spot gravitational waves can only detect them in a narrow band, so researchers are investigating new approached to catch a much wider variety of these ripples in space-time. Nature’s Davide Castelvecci is your guide for a whirlwind three-minute tour of these strategies, which range from watching pulsars to measuring quantum fluctuations.

Nature | 3 min video

Features & opinion

The mpox public health emergency

Virologist and public-health researcher Nicaise Ndembi of the Africa Centres for Disease Control and Prevention (Africa CDC) outlines the body’s decision to issue its first-ever Public Health Emergency of Continental Security (PHECS). “Mpox was declared a PHECS in part to unlock access to emergency resources, including funding, personnel and technical support, but the mpox outbreaks in Africa are a global concern, with the potential for international spread,” writes Ndembi. “Africa CDC asks its global partners to stand with Africa in this critical hour.”

Nature Medicine | 4 min read

Sustainable ‘climatopias’ are possible

Futuristic flood-resistant villages that float or sit on reclaimed land — ‘climatopias’ — can be viable options for climate adaptation, argue climate scientists Idowu Ajibade and Sameer Shah, but only if they are planned and implemented with care. Ajibade and Shah outline six priorities for designing climatopias, including ensuring equity and justice, introducing regulatory guidelines and safeguarding ecosystems.

Nature | 12 min read

Energy ratings for AI

Artificial intelligence (AI) systems are using too much energy, write a group of researchers and leaders from Meta, Hugging Face, Salesforce and others. They suggest an initiative called the AI Energy Star project, inspired by the US Environmental Protection Agency’s Energy Star ratings for products such as light bulbs. “This simple system can help users to choose the most appropriate models for their use case quickly,” argue the authors. And “hopefully, also encourage model developers to consider energy use as an important parameter”.

Nature | 9 min read

AI's energy footprint. A scatter chart showing the total energy consumed by various models for five different tasks such as image generation and automatic speech recognition. The x axis unit is watt-hour. Image generation consumes the most energy and the average is similar to a laptop running for 20 hours.

Source: Unpublished analysis by S. Luccioni et al./AI Energy Star project

QUOTE OF THE DAY

“This is a big dilemma in the aging field — how do you know whether your treatment’s working without waiting for someone to actually die?”

Nobel-prizewinning structural biologist Venki Ramakrishnan explores the science of ageing — and, importantly, separates fact from fiction — in his new book, Why we die. Listen to the Nature hits the books podcast with Ramakrishnan (30 min listen) or read the book review by molecular geneticist Jan Hoeijmakers (6 min read)