Kevin Hall spent 21 years at the US National Institutes of Health and became known globally for his pioneering work on ultra-processed foods. In April he unexpectedly took early retirement, citing censorship under the Trump administration. Now he has co-authored a book with the journalist Julia Belluz that aims to bust myths and challenge wellness orthodoxy on everything from weight loss and metabolism to supplements and wearables. Hall tells Ian Sample what he wants us all to understand about diet, exercise and weight loss, and what led to his departure from the job he loved. Help support our independent journalism at
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