For a long time fat was seen simply as an inert yellow substance wrapping around our bodies, but now that’s changing. Scientists are beginning to understand that our fat is actually intricate and dynamic, constantly in conversation with the rest of the body. It’s now even considered by some to be an organ in its own right. To find out more about the complex role fat plays in our health, Ian Sample hears from co-host Madeleine Finlay and from Declan O’Regan, professor of cardiovascular AI at Imperial College London. Help support our independent journalism at theguardian.com/sciencepod

Madeleine Finlay sits down with science editor Ian Sample and science correspondent Nicola Davis to discuss three eye-catching stories, including the impact of a powerful psychedelic on depression, answers on the death of Russian opposition leader Alexei Navalny, and an explanation to the mystery of why humans have chins. Help support our independent journalism at theguardian.com/sciencepod

Testimonials about the beneficial health effects of magnesium supplements abound online, with influencers claiming that a daily pill can help with everything from anxiety to sleep and brain fog. But do any of these claims stack up? Ian Sample is joined by co-host Madeleine Finlay to find out where the science stands. They also hear from Katherine Tucker, the founder of the Center for Population Health at the University of Massachusetts Lowell. She explains what magnesium is doing in our bodies and the best approach we can take to ensure we are getting enough. Help support our independent journalism at theguardian.com/sciencepod

In late January a new social media site took a certain corner of the internet by storm. Moltbook was conceived as a space where AI assistants could let off steam, chat and compare notes on their bosses, but it quickly became the focus of breathless claims that the singularity had arrived as the bots started badmouthing their humans and plotting an uprising. So what’s the truth about Moltbook? Madeleine Finlay hears from Aisha Down about what it tells us about AI, and about us.. Help support our independent journalism at theguardian.com/sciencepod

The release of the latest batch of documents relating to the late child sex offender Jeffrey Epstein has shed further light on his close relationship with the world of science. To find out why he cultivated scientists and where his interests lay, Ian Sample hears from Dan Vergano, a senior editor at Scientific American.. Help support our independent journalism at theguardian.com/sciencepod

On a recent trip to Lake Geneva in Switzerland, biodiversity reporter Phoebe Weston witnessed the impact of one of the planet’s most potent invasive species, the quagga mussel. In just a decade the mollusc, originally from the Ponto-Caspian region of the Black Sea, has caused irreversible change beneath the surface of the picturesque lake. While ecologists believe invasive species play a major role in more than 60% of plant and animal extinctions, stopping them in their tracks is almost impossible. Phoebe tells Madeleine Finlay how invasive species spread, how conservationists are trying combat them and why some think a radical new approach is needed.. Help support our independent journalism at theguardian.com/sciencepod

Just like men, women are increasingly being told by online influencers that the classic symptoms of middle age could be down to low testosterone. In the second part of this miniseries exploring the hormone, Madeleine Finlay finds out what testosterone supplementation is doing for women. She hears from science journalist Linda Geddes, who is taking testosterone for low libido, and from prof Susan Davis, a consultant endocrinologist and head of the Monash University Women’s Health Research Programme. Susan explains what the evidence really shows about the benefits and risks of women taking testosterone. Help support our independent journalism at theguardian.com/sciencepod

If TikTok influencers are to be believed, testosterone, or T, is the answer to everything from fitness frustrations and fatigue to low libido. But doctors are warning that social media misinformation is driving men to seek testosterone therapy that they don’t need. This in turn comes with risks for health and fertility. In part one of a miniseries exploring the popularity of testosterone, Madeleine Finlay hears from Prof Channa Jayasena of Imperial College London, who is chair of the Society for Endocrinology, about how this craze is manifesting in NHS clinics, and from ‘Sam’ who tells Madeleine about his own journey with the hormone. Help support our independent journalism at theguardian.com/sciencepod

Last week, a UN report declared that the world has entered an era of ‘global water bankruptcy’ with many human water systems past the point at which they can be restored to former levels. To find out what this could look like, Madeleine Finlay speaks to the Guardian’s diplomatic editor, Patrick Wintour, who has been reporting on Iran’s severe water crisis. And Mohammad Shamsudduha, professor of water crisis and risk reduction in the department of risk and disaster reduction at University College London, explains how the present situation arose and what can be done to bring water supplies back from the brink. Help support our independent journalism at theguardian.com/sciencepod

The Guardian’s science editor, Ian Sample, talks to Madeleine Finlay about three eye-catching science stories from the week, including a study that suggests positive thinking can boost immune response. Also on the agenda is the mysterious rise of scabies in the UK, and the discovery that cows are more adept with tools than previously known. Help support our independent journalism at theguardian.com/sciencepod