Читать книгу The GL Diet Made Easy: How to Eat, Cheat and Still Lose Weight - Nigel Denby - Страница 8

GI is a scientifically proven method of categorizing foods according to how quickly the carbohydrates they contain are broken down and absorbed as glucose into the bloodstream. The Glycaemic Index or GI was created by comparing blood glucose levels of volunteers after eating different carbohydrate foods. Volunteers eat an amount of food that provides 50g of carbohydrate. Blood samples are taken from the volunteers at regular intervals over the next two hours to find out their blood glucose and insulin response to the test food. Each food is then given a number depending on how fast the body digested and absorbed the carbohydrate – the higher the number the faster the absorption. The number is called the food’s Glycaemic Index (GI).

55 and under is low Gl 55–70 is moderate Gl

So far, so good.

Every food tested has a GI number telling us how quickly it is absorbed when we eat an amount that contains 50g of carbohydrate. But this is where the major problem with GI crops up. Different foods contain very different amounts of carbohydrate.

For example, to reach the laboratory test level of 50g of carbohydrate you would need to eat about 75g of pasta, so a small portion, BUT you would need to eat a whopping 500g of parsnips to reach the 50g carb level, and how often would we do that outside the laboratory? We love parsnips but not that much! We would generally eat about 100g of parsnips at any one time. So the GI number isn’t based on realistic amounts of food that people usually eat in one sitting. The GI number you get for some foods like parsnips, watermelon and carrots, for example, is high, and if you just looked at the GI, these fine, nutritious foods would be deemed bad foods to be avoided! It’s clear that there are problems with basing a healthy-eating plan on the GI of foods.