Jimmy Doherty discovers the truth about crash diets, revealing what it really means to stay fuller for longer and explores whether astronauts could hold the key to weight loss. Kate Quilton delves into the multi-million-pound collagen drinks market, and finds out how shots of the liquid claim to boost your skin's appearance. In Valencia, Matt Tebbutt checks out Spain's secret summer-friendly superfood tiger nut milk, while Dr Helen Lawal investigates whether popping weight-loss pills can help summer slimmers.