In the year 1750, the average amount of sugar consumed per person per year was four pounds. Today, the average American eats 150 to 170 pounds of sugar each year. It’s no wonder that the United States leads the world in obesity.
The human body wasn’t designed to process sweets and starchy foods in the quantities most people consume today. The obvious consequence is obesity. However, underlying inflammation and the accumulation of excess body fat is something even more worrisome. There is a strong link between elevated blood sugar and brain degeneration.
Unfortunately for most Americans, the body’s ability to handle sugar is severely taxed due to the standard American diet, which is heavy on breads, pastas, pastries, cereals, and other grain-based foods (primarily refined rather than whole grain). Potatoes, sweet coffee drinks, sodas, and desserts of all kinds round out the picture and the waistline.
Insulin resistance is well-known for its links to heart disease, obesity, and type 2 diabetes; however, a growing body of research links insulin resistance to a decline in cognition as well.
Insulin is a hormone whose job is to usher blood glucose into the body’s cells for energy production or store it as fat, keeping blood sugar levels at a steady amount. When your body becomes resistant to insulin, the excess sugar just sits in the blood stream, causing destruction of tissue in the body and the brain.
Insulin resistance is caused by a diet high in sugars and starch, usually combined with inadequate exercise. Every time you eat something sweet or starchy, it causes your blood sugar to spike. In response to the spike in blood-sugar, the pancreas pumps out insulin to eliminate that sugar.
If blood sugar remains high, the pancreas compensates by secreting an overabundance of insulin into the bloodstream. This can cause blood sugar levels to drop too low, leading to fatigue and sugar cravings. It also triggers the adrenals, the glands that respond to stress, to release stress hormones to help raise overly low blood sugar.
These constant surges of insulin and stress hormones eventually overwhelm the body’s cells. Chronic stress is linked with insulin resistance because it causes the continual release of the stress hormone cortisol. High cortisol blunts cellular receptors, so they become resistant to insulin.
Symptoms of insulin resistance include:
- Fasting blood sugar level over 100 mg/dL
- Fatigue after meals
- Craving sugar after meals
- Constant hunger
- Difficulty losing weight
- Excess belly fat or a waist girth that is equal to or larger than hip girth
- Frequent urination
- Increased thirst
- Prone to insomnia
- Not feeling rested after eight hours of sleep
- Facial hair and thinning hair in women
- Enlarged breasts in men
- Polycystic ovary syndrome (PCOS)
- Hormonal imbalances
Because their blood sugar is swinging between highs and lows, people with insulin resistance also often exhibit these symptoms of low blood sugar, or hypoglycemia:
- Craving sweets
- Irritability, shakiness, or light-headedness if the person goes too long without eating
- Dependence on coffee or other stimulants for energy
- Moody, emotional
- Spaced-out, forgetful when hungry
- Wake up at 3 or 4 a.m., often feeling anxious
- Feel woozy or blacking out somewhat when going from sitting to standing
Insulin’s Role in the Brain
Although we associate the pancreas with the production of insulin, new research suggests the brain also produces insulin locally. Appropriate levels of insulin help the brain manage glucose levels, produce important brain chemicals called neurotransmitters, and regulate inflammation. The same dietary and lifestyle factors that cause insulin resistance in the body also impair insulin function in the brain, promoting conditions that cause memory loss and cognitive impairment. Studies have established clear links between type 2 diabetes and an increased risk of Alzheimer’s disease (sometimes called type 3 diabetes), dementia, and mild cognitive impairment.
Obesity and a Potbelly
Research shows the risk of dementia and Alzheimer’s increases considerably when a person is obese or overweight. Having a potbelly, or excess abdominal fat, makes being overweight even riskier. Studies show that even those who are at a normal weight but have a potbelly are at an increased risk of developing MCI and Alzheimer’s. One study showed that persons between the ages of 60 and 70 who had the largest waistlines scored the worst on cognitive tests.
Other studies show that having a large belly in middle age triples or quadruples the risk of developing dementia later in life. Just being overweight increases the risk by 80 percent. The risk jumps to 230 percent for overweight people with a large belly and 360 percent for those who are classified as obese with a potbelly.
Since autopsies show that signs of Alzheimer’s manifest in the brain decades before symptoms, your weight in your 30s, 40s, and 50s is a powerful determinant of your brain health in older age.
Many people start to feel their memory slipping during midlife (ages 45 to 65). Although some experts attribute this to normal aging, those wondering how to improve their memory can find some answers on their dinner plate and at the local gym.
Research shows that losing weight can improve your memory as can exercise, which has long been recognized as a powerful means of prevention for dementia and Alzheimer’s. Regular exercise is another way to maintain insulin sensitivity and has been shown to dramatically lower the risk of dementia and Alzheimer’s.