Читать книгу The Little Book of Calorie Burning - Литагент HarperCollins USD, Ю. Д. Земенков, Koostaja: Ajakiri New Scientist - Страница 6

Each of us has a Resting Metabolic Rate, or RMR – you might know it as your ‘metabolism’. It is the rate at which your body burns calories when you are doing absolutely nothing. As you’ve probably noticed, there are people who can pig out on a Chinese takeaway followed by a family-size bar of Dairy Milk yet remain thin as a rake. They are lucky in that their RMR is high, giving them an unfair advantage.

Your basic RMR is largely governed by genetics, as is your body shape. If you have short, porky parents, you’ll probably have to work harder at keeping your weight under control than those whose parents are tall and slender. However, there are ways you can boost your own RMR, as well as ways in which you can totally screw it up.

So what’s the worst thing you can do for your RMR? Any guesses? Yes, dieting – especially crash dieting. When you cut back drastically on the amount you’re eating, your body thinks it is starving and slows down your metabolism in order to guard your fat reserves. It actually starts storing more calories as fat than it was doing before, because it’s not sure when it’s going to get its next square meal. Once you stop dieting, your metabolism stays at this lower rate for a while, meaning that any new weight is stored as fat. It’s common to put weight back on faster than you lost it – and to put on a bit more padding as well. You then panic and start dieting again and get caught in a never-ending cycle of yo-yo dieting. After a while, your RMR forgets what is normal and stays at its new, lower rate – and you’re stuffed, basically!

If you cut down your food consumption too much (less than 1,100 kcal a day for women or 1,400 a day for men) you will soon start experiencing all kinds of unwanted side effects as your body tries to protect itself – and some of these will stay around long after you’ve stopped dieting. If you see a woman with a coating of fine, downy hair on her face or back, there’s a good chance she was anorexic at some stage. She may not be anorexic any more, but her face will be hairy for life – it was her body’s way of trying to keep her warm when she didn’t have enough flesh on her bones to act as insulation.

Other possible consequences of eating too little (or not getting enough essential protein, vitamins and minerals) include very dry skin that is prone to crows’ feet and wrinkles, thinning hair that splits easily, and some women find that their periods stop. Plus, the long-term lowering of their RMR will mean that they feel knackered the whole time. If you wanted to lose weight in order to be more attractive, I’m guessing this is probably not part of the package you had in mind.

RMR accounts for between 65 and 75 per cent of all the calorie energy your body burns. It is used for basic functions like breathing, regulating body temperature, forming new cells, releasing the right kind of hormones, using your brain and all the other things we need to do to stay alive. The good news is that muscle cells burn calories much more effectively than fat cells do, so the more muscle you have, the more you can afford to eat. A pound of muscle burns between 50 and 60 kcal a day while a pound of fat burns fewer than 10. Therefore, the way to raise your RMR is to build more muscle and replace the fat. Simple as that… Almost.