In 1964, A Scotsman survived without eating for 1 year and 17 days and consequently only pooping every 40-50 days. He lived entirely off his excess body fat, yeast, and a multi-vitamins. He ended up losing 125 kg of weight. – WTF Fun Facts
Source: https://www.abc.net.au/science/articles/2012/07/24/3549931.htm