Читать книгу The Insulin Factor: Can’t Lose Weight? Can’t Concentrate? Can’t Resist Sugar? Could Syndrome X Be Your Problem? - Antony Haynes - Страница 7

1 Tell Me About Insulin Resistance

What is insulin?

Although we’ve been talking about Insulin Resistance you shouldn’t think that insulin is really the bad guy in all of this. Although it is a dangerous hormone when it is produced in excessive amounts, as in the case of Insulin Resistance, it is actually vital for the body to function normally and to control how the body uses and stores glucose. Glucose is what gives your muscles and other organs the energy to function. Too little insulin is also just as dangerous, if not fatal, as seen in people who have type I diabetes: they can’t produce insulin so they need to regularly inject themselves with this hormone. Without these injections their blood sugar level would be too high which has serious and indeed fatal consequences. So, as with many things in life, it is a question of balance: too much or too little insulin in the body are just as dangerous for your health.

Too much insulin can make you overweight and tired, and increase your risk of heart disease and diabetes; too little insulin means high blood sugar levels which damages your internal organs.

What exactly does insulin do?

Insulin is one of many hormones in the body, and is also a protein. It is made in and secreted from cells in the pancreas called the Islets of Langerhans, named after the German pathologist who discovered them. The pancreas is one of the most important organs involved in digesting food and storing the nutrients in what you eat in your body’s cells. To give you an idea of proportion, about 98 per cent of the cells of the pancreas are devoted to digestion, with the Islets of Langerhans cells accounting for the remaining 2 per cent. The cells in the Islets of Langerhans that produce insulin are called beta cells, or B-cells. There are also alpha cells, or A-cells, which produce glucagon, a hormone that raises blood glucose levels.

Insulin and carbohydrates

Insulin’s main function is storing glucose from the bloodstream into cells. This first involves converting glucose released into the bloodstream from the digestion of foods into glycogen. The body only has a limited capacity to store glycogen – the primary stores of glycogen in the body are the liver and muscles – so all other glucose is then stored as fat, known as adipose tissue. People who have Insulin Resistance typically store this fat around their middles. Either way, insulin lowers the concentration of glucose in the blood.

Insulin and proteins

Insulin doesn’t just determine what happens to the carbohydrates that we eat, it also plays an important part in the way that proteins are metabolized. During the digestive process, many proteins are broken down into amino acids, which are then transported into the bloodstream. Insulin promotes the transport of amino acids into the liver and muscle cells. In this way it is involved in storing proteins away in the body, just as it does carbohydrates. It also inhibits the breakdown of protein in muscle for fuel. This is because if insulin is present, the body concludes that there is adequate glucose available and there is no need to break down muscle proteins for energy.

Insulin and fats

Similarly, insulin also has command over how fats are handled in the body. It inhibits the release of fats from fat tissue. This means that insulin prevents the use of your fat for energy in a similar way to how it prevents your body breaking down proteins. Insulin also promotes the production of fatty acids in the liver, which increases the amount of fats (bad cholesterol and triglycerides) circulating in the bloodstream – a potential risk for heart disease when present in excess.

Essentially, what all this means is that insulin prevents the body from overly using itself up and breaking down structural proteins and fats, especially if you do not eat enough food. Obviously this worked well when we were hunter-gatherers, as it meant the body did not begin breaking down its reserves at the first sign of hunger. These days, few of us go hungry for any length of time, so insulin’s supreme ability to store glucose at fat for future use is not nearly so important. Indeed, the modern diet that encourages high insulin levels means that the body stores more glucose as fat and we are at greater risk of becoming overweight and obese.

How much insulin your body releases depends on what you eat

Under normal conditions, insulin is produced moments after we eat something, so insulin levels will always be higher after we eat than before. As our blood glucose levels increase, the pancreas secretes insulin into the blood and insulin then performs the storage roles described above. The rate at which the blood glucose level increases is primarily determined by the amount of carbohydrate you eat. The volume of amino acids (proteins) you eat also has an effect on insulin production but much less than carbohydrates. If you eat a portion of carbohydrates, for example, this raises your blood glucose far than if you ate the same amount of protein, resulting in more insulin being released to store the glucose away. Once the glucose and amino acids are stored away, levels of insulin reduce accordingly. In this way, insulin levels vary throughout the day depending on the food we eat.

Carbohydrates raise blood sugar more than proteins. This means that your body produces more insulin when you eat carbohydrates than protein.

Insulin Resistance

If the body is continuously exposed to high levels of insulin, the insulin receptor cells in the liver, adipose (fat) tissue and muscle start to become inefficient. The way insulin binds to the receptors in the liver, fat and muscle tissues becomes partially blunted. In essence, this means some tissues in the body become resistant to the effects of insulin so that insulin is not able to carry out its normal role. The body recognises that there is too much glucose in the bloodstream so the pancreas produces even more insulin to try and compensate. When your body is consistently producing high levels of insulin it is a sure indication that you are resistant to insulin, hence the term ‘Insulin Resistance’. The pancreas will ultimately become exhausted and unable to produce the insulin needed to maintain optimal glucose levels and this is when you become diabetic.

The harm Insulin Resistance does

We already touched on this in the introduction but it is worth looking at the knock-on health effects of Insulin Resistance in detail.

You may wonder why it is vital for the body to keep down glucose levels in the bloodstream. As much as we need glucose to function, glucose at too high a level leads to oxidation and this causes tissue damage. This is what happens in poorly controlled diabetes, which can lead to peripheral neuropathy, renal conditions and cataracts. Since high blood glucose is so damaging to your health, your body will do everything it can to maintain normal glucose levels. The only means the body has to do this is with insulin. As you will see, the list of health conditions associated with Insulin Resistance is long and unpleasant:

Lay Description	Technical Term
Heart disease	Coronary Heart Disease (CHD)
Obesity	Body Mass Index (BMI) of 30 or over
Breast cancer	Breast Cancer
High blood insulin levels	Hyperinsulinaemia
High blood cholesterol levels	Hypercholesterolaemia
High blood pressure	Hypertension
Adult-onset diabetes	NIDDM (non-insulin-dependent diabetes mellitus)
Blood sugar problems	Dysglycaemia
Polycystic ovary syndrome	PCOS
Gout	Hyperuricaemia
Arthritis	Osteoarthritis
High blood fat levels	Hypertriglyceridaemia or hyperlipidaemia
Low good cholesterol	Low HDL
Impaired GlucoseTolerance	Impaired Glucose Tolerance
Low blood glucose	Hypoglycemia
Fuzzy head after eating carbs	Carbohydrate Sensitivity

What causes Insulin Resistance?

While your genes (see chapter 11) can be a contributory cause of Insulin Resistance – there is a higher risk of Insulin Resistance amongst people of South Asian origin – generally speaking there are numerous controllable factors that cause or exacerbate Insulin Resistance. The most significant one is related to body weight, or more specifically body over-fatness, especially around the middle. This is compounded by a sedentary lifestyle and the resulting lack of muscle tissue, by ageing, stress, high blood pressure and by excess consumption of refined carbohydrates, over-processed food, saturated fat and processed vegetable fat. Interestingly, digestive health also plays an important role. Obviously, with the exception of genetic factors and ageing, many of these factors are under our control and we can take positive action. You can look at how these factors are playing a part in your health in chapter 3, with the Insulin Resistance questionnaire.

Contributory factors in Insulin Resistance

High intake of sugar and refined carbohydrates

Sedentary lifestyle

Being overweight or obese (BMI over 30)

Excess body fat around the middle (abdominal obesity)

Stress

High blood pressure

A lack of vital nutrients

Genetic factors

Increased inflammation in the body

A diet high in saturated fat

A diet high in processed vegetable fat

Insulin Resistance results from the body’s protective mechanism to prevent high blood glucose. Insulin Resistance is an extremely common problem that can cause disease and limit life span. There are many things that raise blood glucose (e.g. refined carbohydrates, sugar stress) but just one that lowers it: insulin. Insulin Resistance is reversible if you make changes to your diet and lifestyle.

Summary of key points

The food you eat directly affects your insulin levels

Insulin profoundly affects carbohydrate, protein and fat metabolism

High levels of insulin are dangerous and contribute to heart disease

Diet and lifestyle are the main causes of Insulin Resistance; there is no single genetic cause of Insulin Resistance.