British actor Tom Hiddleston suffered crippling headaches during his poverty awareness challenge as he was forced to battle his addiction to caffeine. The Thor star spent a week surviving on just $1.50 (£0.93) a day to support a United Nations Children's Fund (UNICEF) campaign in aid of starving children, and he had to give up tea and coffee to keep within his tight budget. Hiddleston admits cutting out caffeine made him feel ill, but he eventually found he could live without it. In a piece for Britain's Harper's Bazaar magazine, he writes, "I realised that I have an addiction to caffeine and coffee. For most of the morning on the first few days I found it very hard to concentrate on simple tasks, without a cup of coffee. This won't come as news to anyone who has ever tried to go cold turkey - and to stop taking a substance they are addicted to. But after a few days, my head cleared, and I found a more sustainable equilibrium." Hiddleston, who completed the Live Below The Line challenge last month (Apr13), admits the scheme helped him become a better cook and stop being so wasteful with food. He adds, "(It) made me think about food in an entirely different way. I had to plan better, to budget better. I didn't waste a penny, or a crumb. It was a test of mind and will power... I had to cook my own meals and not buy food on the go... "I enjoyed cooking during my Live Below The Line week more than I ever have. I enjoyed the meals I made for myself, more than I enjoy the food I would normally buy on the go - a coffee, a sandwich, lunch at a cafe, or a take-away. "Through this challenge I learned the importance of preparing food carefully. I learned to be grateful for every single mouthful. I understood how wasteful I used to be." Other stars to take part in the challenge include Hollywood actor/director Ben Affleck and Harry Potter's Bonnie Wright.