Have you ever wondered why you may eat the same foods as someone else, but they have tons of energy, and you don’t? Or why some days you have energy in the morning, but other days you have it at night? Or why, after lunch, you feel like you need a nap? Understanding how you uniquely respond to food and then learning how you can modify behavior to change how your body responds has the potential to give you the power to better shape your energy levels.
With new research and technology, we are at the cusp of a revolution that will finally allow us to understand how we each respond to food. This is the first in a three-part series designed to help you understand how the body responds to food. We will expose you to emerging research and technology that is beginning to provide insight into our huge interindividual variability. We will look at key strategies that will help you improve and take more control of your health.
What is metabolic health?
Your metabolism is a series of chemical processes that break down the food you eat into the energy and nutrients your body needs to maintain the critical processes required for life. Metabolic health can be defined as how well your body functions in completing these processes. In medical practice, ideal metabolic health is typically measured as having optimal levels in all of the following measures: fasting blood glucose, triglycerides (fat in the blood), HDL (commonly known as “good cholesterol”), blood pressure, waist circumference and HbA1c (a measurement of blood glucose over three months). A recent study indicated that only 12.2% of American adults have optimal metabolic health.
Metabolic health is affected by almost every aspect of daily life, but diet, sleep, physical activity and stress are the key modifiable contributors.
How does your blood glucose response inform your metabolic health?
Studies have indicated that disordered blood glucose levels are correlated with negative outcomes of other measures of metabolic health, including hypertension (high blood pressure), hypertriglyceridemia (high blood triglycerides) and low HDL levels. Given the interconnection of the various aspects of metabolic health and their outcomes, glucose levels offer a window into overall metabolic health.
The basic biology of blood sugar control
Most of your body’s mechanisms work to keep your bodily functions working within an optimal range, a state called homeostasis. Blood glucose contributes to homeostasis and is regulated to stay within a set range. Blood glucose levels are controlled by the pancreas using the hormones insulin and glucagon. When you eat something with carbohydrates, the carbohydrates are broken down during digestion into simple sugars including glucose, which is absorbed into your bloodstream, increasing your blood glucose level. The pancreas detects this increase and releases insulin into your blood. Receptors on muscle, liver and fat cells detect insulin and signal them to take up the glucose to either use as energy or store, reducing the amount of glucose in the blood. As a result, blood glucose levels will decrease over time following the meal. They can also decrease more rapidly with exercise. If blood glucose levels dip below the optimal threshold, glucagon, the partner hormone to insulin, is released. Glucagon triggers the liver to release glucose from storage and manufacture more, thereby either raising or maintaining blood glucose levels. The pancreas continually adjusts the insulin and glucagon levels to keep blood glucose in an optimal range. Glucose levels are often shown as milligrams of glucose per deciliter of blood written as mg/dl.
Figure 1 illustrates how blood glucose levels might look over one day for a person with healthy glucose control eating healthy meals.
In contrast, Figure 2 shows what unhealthy or disordered glucose control might look like over a similar one-day period. Consistent disordered glucose response is seen in the metabolic disorders of prediabetes and type 2 diabetes (T2D) but likely begins before these diagnoses are made. Spikes and crashes can occur for people without these disorders when eating high-carbohydrate, low-nutrient-density meals or foods.
With prediabetes or TD2, often two interrelated problems occur: Problem 1: Insulin Resistance (IR): In IR, cells that detect insulin in the blood resist insulin’s signal to take up the glucose, so less glucose goes into the cells, leaving more glucose in the blood. This results in both increased baseline glucose levels and higher glucose in the blood after meals. Problem 2: Reduced Insulin Output: In this case, the body’s ability to make insulin is reduced. As with IR, with less insulin available to signal the cells to take up glucose, more remains in the blood—both after meals and between meals. These higher levels of glucose in the blood, known as hyperglycemia, can result in spikes after meals. It also likely means that extra glucose is already in the blood before the next meal, potentially causing an even bigger spike. Blood sugar crashes can also occur, leading to fatigue and sugar or carbohydrate cravings. In a person with diabetes, this crash can trigger more severe symptoms such as blurred vision, loss of consciousness and even coma. Insulin resistance and reduced insulin output are thought to be caused by a combination of complex factors involving the environment, lifestyle and genetics. The predominant lifestyle factors shown to have a high correlation with insulin resistance include lack of physical activity, sedentary lifestyles and unhealthy dietary patterns (including excessive caloric intake and diets high in processed foods). While the above illustrations show the contrast between a normal and disordered blood sugar, they depict clear cases of healthy versus disordered response. Most individuals vary along a spectrum of responses between these examples. Why is there concern over disordered blood sugar control? Chronic hyperglycemia, which refers to a pattern of frequent high blood sugar levels, has been linked to markers of chronic inflammation and favors the growth of existing tumor cells. Chronic inflammation can cause damage to both blood vessels and nerves throughout the body, and hyperglycemia supports the growth of energy-hungry tumor cells and increases cancer risk for many cancers. In addition, studies have shown that type 2 diabetes increases the risk for a wide variety of diseases, including:
Cardiovascular diseases such as heart attacks and strokes.
Chronic kidney disease that can result in the need for dialysis.
Vision problems and blindness.
Nerve damage, which starts as tingling, burning or numbness and which may lead to complete loss of feeling (neuropathy).
Nerve damage that leads to irregular heartbeats.
Reduced fertility.
Increases in certain cancers including pancreatic, breast, endometrial, colorectal, liver and bladder.
Diseases related to long-term brain health, including Alzheimer’s and dementia.
A poor and disordered glycemic response can not only affect your long-term health, but it can also affect your daily life by causing food cravings, modifying energy levels and even disturbing sleep. Part 2 of this series will look at the emerging research and technology that has the potential to bring new understanding and solutions to improving glycemic control.
Resources Click here for the full list of resources.
Jill Goldring, MNSP, MSIE
Jill Goldring is a nutritionist, engineer, avid gardener, beekeeper and healthy food enthusiast. Nutrition is a second career for Jill after a successful Silicon Valley career managing high-tech projects. Jill is interested in the intersection of diet, glycemic response, microbiome and metabolic health outcomes. Her goal is to make positive changes to food systems and services that provide healthy food, nutrition education and nutrition technology to underserved communities.
She is a volunteer with the Samaritan House San Mateo. She manages a pilot program that pairs nutrition education focused on glycemic response and CGM (continuous glucose monitor) technology for the free medical clinic’s food pharmacy for diabetic patients.
She has Master’s in Nutrition Science and Policy from Tufts University Friedman School of Nutrition Science and Policy, a BS in Industrial and Systems Engineering from USC and an MS in Industrial Engineering from Stanford University.
Instagram: @guthappynutrition