Cutting calories leads to a slowing of metabolism London - Arabstoday IF you are on a diet, look away now. Losing weight is twice as hard as thought, scientists said last night. After factoring in how metabolism slows down as we shed pounds, they announced that dieters’ expectations have been too high. And official guidance that cutting 500 calories a day will result in a pound of weight being lost a week is plain wrong. But there is some good news, the same experts have created on online calculator that allows would-be slimmers to adjust their expectations and gain a more realistic picture of what they can expect to achieve The Body Weight Simulator website – at bwsimulator.niddk.nih.gov – estimates how much less that person will have to eat, or how much more exercise they’ll have to do reach their goal. Official advice in the UK and the U.S. has long been that cutting out 500 calories a day will lead to weight loss of a pound a week. But the calculation assumes that weight loss is steady and does not take into account that a person’s metabolism slows down as they lose weight, making subsequent pounds harder to shed. This means weight is twice as hard to shift, the American Association for the Advancement of Science’s annual conference heard. The old system says that cutting 100 calories a day will lead to the loss of 10lb a year. The revised rule predicts just 5lb will be shifted. Rather than expecting too much, dieters should be patient, said Boyd Swinburn, an obesity expert from Deakin University in Melbourne, Australia. Advising slimmers not to set their sights on more than a half a pound of weight loss a week, he said: ‘This is extremely good. This is a marathon not a sprint.’