In this Food Unwrapped diet special, Jimmy Doherty, Kate Quilton, Matt Tebbutt and guest presenter Kiran Jethwa cross the globe to unearth the very latest dietary trends and scientific advances in the world of weight loss. In Los Angeles, home of the body beautiful, Kate investigates reports that caffeine could be a powerful secret weapon in the battle of the bulge. Could a double espresso really help us burn extra calories, even after we finish exercising? Kate meets one of California's leading sports scientists to find out. Jimmy visits Belgium on the trail of the dieter's holy grail: a chocolate that could be good for you. The secret? It's a probiotic chocolate bar, packed with bacteria that are supposed to keep us healthy and even help us stay slim. But how does probiotic chocolate stack up against other gut-friendly foods such as sauerkraut or yoghurt?

• Matt Tebbutt
• Andi Oliver
• Kate Quilton