Читать книгу The GL Diet Made Easy: How to Eat, Cheat and Still Lose Weight - Nigel Denby - Страница 6

There are three main nutrients in foods that give us energy in the form of calories – carbohydrate, protein and fat (alcohol also gives us energy but we’ll put that to one side for a moment!). When we eat a meal, carbohydrates are digested and absorbed first, followed by proteins and then fats. Carbohydrates are broken down into simple sugars (glucose); proteins are broken down into amino acids; and fats are broken down into fatty acids before being absorbed into the bloodstream.

The carbohydrates in foods affect our blood glucose and insulin levels the most. Insulin is needed by most cells in the body to act like a key and ‘let in’ the glucose from the blood so it can be used as fuel by the cell or so it can be stored. The amount of glucose that is floating around in our blood has to be carefully controlled within tight limits – too low and we will feel faint and dizzy; too high and our internal organs can be severely damaged. So it is the job of insulin to ensure that it keeps blood glucose levels under tight control.

Glucose is mainly stored in our muscle and liver cells to be used for energy as needed. Much of this stored energy is used when we are physically active. When the muscles and liver are full and can’t store any more glucose, the only thing insulin can do is transfer the excess to other body tissues. This excess of energy is stored as FAT. Yes, those awful wobbly bits!

The carbohydrates in high-GL foods are very rapidly broken down to glucose and absorbed. This causes a huge rush of glucose into our bloodstream (glucose spike). The more glucose there is in the blood, the more insulin is produced (insulin spike). As a safety mechanism, insulin has to rapidly move this large amount of glucose flooding the bloodstream into our muscle and liver cells to be stored for later use. This can happen very quickly and cause blood glucose levels to drop suddenly (blood glucose crash). Don’t worry if this seems complicated – you don’t have to understand it all for the diet to work and we have a diagram on page 12 to show you what we mean.

When our blood glucose and insulin levels fall below a certain level, this triggers hunger signals in the brain. It tells us that we need to eat more because our blood glucose levels are falling quickly – as a result we crave more high-GL foods to satisfy the apparent hunger! What the brain doesn’t realize is that we ate a doughnut (or any high-GL food) only an hour ago! This turns into a vicious cycle as the rapid fall in blood glucose prompts us to crave more high-GL foods – which actually caused the problem in the first place!

High-GL foods eaten = blood glucose spike = blood insulin spike = blood glucose crash = craving for more high-GL foods = weight gain!

Fear not – this vicious cycle can easily be broken.

The carbohydrates in low-GL foods are broken down to glucose and absorbed more slowly, causing only a small rise in blood glucose levels and a corresponding small rise in blood insulin levels. As a result, glucose is moved into our muscle and liver cells at a slower pace and blood glucose levels are more stable. Eating low-GL foods every three to four hours helps keep our blood glucose levels steady – meaning no glucose and insulin spikes, no blood glucose crash and (you guessed it) NO CRAVINGS AND OVEREATING!

If we eat low-GL foods, we store less excess energy and blood glucose levels are kept stable, giving a slow-release, prolonged energy supply. This enables us to go about our activities with fewer cravings, feeling more balanced and of course ultimately storing less fat.