Unfortunately, as a population, Americans have continually worsening metabolic health. Only 12% of American adults can be described as metabolically healthy. Less than one-third of people at a healthy weight, 8% of people who are overweight, and 0.5% of people with obesity meet the criteria for metabolic health.1 The vast majority of American adults are not metabolically healthy! Just like fitness, small positive choices that you make each day take you closer and closer to achieving metabolic health.
What It Means to Be Metabolically Healthy
Metabolic health is a measure of how efficiently and effectively your body can use nutrients from food (and stored energy) and convert them into fuel your body cells can use to grow, repair themselves, reproduce, and move. Metabolic health describes your overall health.
How Your Metabolism Works
Metabolism is the sum of every chemical reaction in your body that is involved in converting food or stored energy into fuel for your body cells. Body cells use this energy to repair damaged cells and tissues. This process is called anabolism.
After you eat, your body is very busy breaking down the carbohydrates, proteins, and fats you have just consumed into their simplest components so they can be absorbed from your intestines and transported to your cells. This process is called catabolism.
Metabolism is a balance between anabolic and catabolic processes.
Glucose (Carbohydrate) Metabolism
The primary role of carbohydrates is to supply energy for your body's cells. Complex carbohydrates are broken down into simple sugars. Glucose and fructose are examples. When your cells need energy, bonds between carbon atoms in glucose are broken to release energy that your cells can use.
Since many cells preferentially use glucose for energy, your body can also convert amino acids from proteins and fatty acids into glucose. Excess glucose is stored as glycogen, primarily in the liver and muscles.2
<p class="pro-tip"><strong>Keep reading about </strong> <a href="/blog/glucose-metabolism">glucose metabolism and weight loss</a>.</p>
Insulin and glucagon optimize glucose metabolism
Glucose levels in the blood are tightly controlled. Both too high and too low blood glucose can have serious health consequences. Insulin-secreting cells in the pancreas respond when blood glucose is too high. Insulin binds to cell receptors and transports glucose out of the bloodstream and into body cells. Glucagon is released from the pancreas when blood glucose is too low. Glucagon signals liver cells to break down glycogen and secrete glucose into the bloodstream.3
Problems with insulin regulation hinder glucose metabolism
When insulin-producing cells in the pancreas are damaged (type 1 diabetes) or body cells become resistant to insulin's effects (type 2 diabetes), blood sugar levels are not well controlled. Persistently elevated blood glucose damages blood vessels.
Several inherited disorders of carbohydrate metabolism exist, but these are relatively rare. These disorders are usually because of a gene mutation that changes the structure and function of an enzyme used in carbohydrate metabolism.
<p class="pro-tip"><strong>Read about </strong> <a href="/blog/reverse-insulin-resistance">insulin resistance and how to reverse it</a>.</p>
Proteins are made up of amino acids and are used throughout the body for both structural and functional purposes. Proteins are broken down into their component amino acids and then reassembled to make enzymes, antibodies, and hormones, which all serve important functions in the body.
Amino acids can also be recycled into structural proteins such as collagen, elastin, keratin, actin and myosin. Ligaments and tendons bind bones to bones and muscles to bones, respectively, and are made of collagen. Actin and myosin are contractile fibers that make up muscle.4
Exercise optimizes protein metabolism
Muscle tissue is high in protein. Resistance training stresses muscles, which increases the demand for amino acids to build muscle fibers. In one study, researchers measured amino acid turnover during the recovery period after resistance exercise and found a higher rate of muscle tissue synthesis and breakdown.5
<p class="pro-tip"><strong>Learn about </strong> <a href="/blog/anaerobic-exercise">14 health benefits of strength training</a>.</p>
Inactivity and insufficient muscle recovery slow protein metabolism
Inactivity disrupts the balance between muscle building and breakdown. More protein in muscle is broken down than is used to build new muscle. Physical and emotional stress increase cortisol release (stress hormone), which can also increase muscle breakdown.6
Insufficient muscle recovery after strength-building exercise may be counterproductive. Without enough time to repair muscle fibers, damage and inflammation will accumulate.7 These cellular reactions slow the muscle-building process.
Fat (Lipid) Metabolism
There are three main types of lipids: triacylglycerols, phospholipids, and sterols. These high-energy molecules are used by cells to make cell membranes, store energy, and act as signaling molecules. Excess energy from food is stored in adipose (fatty) tissue. Fats can store much more energy in a smaller space than carbohydrates.
Fats also play an important role in the brain by helping form nerve cell membranes, insulate nerve cells, and speed up nerve signal transmission throughout the body. Fats insulate and protect other body organs as well. Vitamins A, D, E, and K rely on fats to be absorbed into the body.
Exercise can help optimize fat metabolism
How quickly fat is metabolized depends on energy demands. Increased exercise duration and intensity can speed up fat metabolism. In most people, exercise intensities between 47% and 52% of maximal oxygen consumption (VO2 max) lead to maximal fat metabolism.8
Poor sleep can hurt fat metabolism
Decreased sleep quality or quantity can lead to insulin resistance, increased ghrelin (hunger hormone), decreased leptin (fullness hormone), decreased physical activity, and increased inflammation. These changes can increase your risk of diabetes, obesity, and cardiovascular disease.9
Several inherited lipid metabolism disorders affect how fats are used and stored in the body.
<p class="pro-tip"><strong>Learn 7 ways to </strong> <a href="/blog/boost-metabolism">naturally boost your metabolism</a>.</p>
How Does Metabolism Affect Blood Sugar?
Although fat, glucose, and protein metabolism all contribute to metabolic health, the two factors with the greatest impact on metabolism are maintaining stable blood sugar and getting enough exercise. Insulin and exercise are anabolic. Insulin aids in storing excess energy as glycogen or fat. Exercise helps build muscle from protein.
Which carbohydrates you choose to consume, how they are packaged in your diet, and how your body metabolizes carbohydrates will all affect metabolism and the combination of glucose, fats, or proteins your body burns for energy.
Insulin resistance disrupts metabolism because glucose stays in your bloodstream instead of entering cells to be used for energy. Increased insulin levels lead to fat storage and weight gain. Blood sugar is a key indicator of how well your metabolism is functioning. When you have metabolic flexibility, average and fasting glucose levels stay within an optimal range, and you experience minimal glucose spikes after eating. In this state, your metabolism is functioning well.
Optimally, you supply your body with the nutritional calories it needs to function without providing excess calories that are stored as fat. Excess calories contribute to obesity, a chronic disease that adversely affects metabolic health.
Knowing what the optimal number of calories you need and in what combination of fat, protein, and carbohydrates is the million-dollar question. Each person's metabolic response is unique, and it may fluctuate throughout the day in response to triggers such as diet, exercise, and stress.
Your basal metabolic rate (BMR) is the minimum number of calories your body needs to function at rest. People with a fast metabolism burn more calories at rest. Therefore, they have a higher BMR. Conversely, people with a slow metabolism burn fewer calories at rest and have a lower BMR. However, having a higher BMR does not mean you will be thin. Carrying excess body weight makes your body work harder and therefore increases BMR.
Besides your BMR, your body's metabolic rate is determined by the thermic effect of food and energy used during physical activity. Digesting, transporting, and storing nutrients consume about 5% to 10% of your energy. Physical activity uses about 20%. But, of course, this depends on how active you are.
<p class="pro-tip"><strong>Learn more about </strong> <a href="/blog/neat-weight-loss">non-exercise activity thermogenesis for weight loss</a>.</p>
Slow Metabolism and Blood Sugar
Slower metabolism (lower BMR) means that you burn fewer calories at rest, which can increase your propensity for weight gain, but does it affect insulin resistance and blood sugar? In one animal study, researchers found that mice with lower BMRs had metabolism-specific pathways that increased their risk of developing insulin resistance and type 2 diabetes. More research is needed to see if this also applies to humans.10
High (Fast) Metabolism and Blood Sugar
The biggest factors affecting your BMR are your fat-free mass (FFM) and fat mass (FM). However, researchers found that two people with the same body composition can have a 26% variance in BMR.11 Resistance exercise stresses muscle, which increases FFM and BMR. Having a faster metabolism is at least partially due to increased FFM. Exercise also helps control blood sugar. More research is needed to determine if there are any stronger links between fast metabolism and blood sugar.
Metabolic Disorders Related to Blood Sugar
Metabolic disorders affect how your body obtains energy from food. Metabolic disorders can be inherited or acquired. Insulin resistance, prediabetes, and type 2 diabetes are on the spectrum of disorders that affect glucose metabolism and blood sugar. The World Health Organization classifies type 2 diabetes as a metabolic disorder. Obesity is a risk factor for insulin resistance, prediabetes, and type 2 diabetes and is also classified as a metabolic disorder.12
<p class="pro-tip"><strong>Learn more about </strong> <a href="/blog/insulin-resistance-vs-prediabetes">insulin resistance vs pre diabetes</a>.</p>
Glycogen storage disease is an example of an inherited metabolic disorder that primarily affects glucose metabolism. Inherited metabolic diseases are usually due to a missing enzyme or vitamin that is essential for metabolism.
Does Metabolic Syndrome Cause High Blood Sugar?
Metabolic syndrome is a cluster of risk factors that are specific to cardiovascular disease. Metabolic syndrome increases the risk of diabetes, heart disease, and stroke. Obesity is the primary risk factor for metabolic syndrome.13
Metabolic syndrome is characterized by the following factors:13
- Altered glucose metabolism, which leads to high blood sugar
- Elevated triglycerides
- Reduced HDL (good) cholesterol
- Increased blood pressure
Metabolic syndrome is diagnosed when three of the following five health markers are no longer in the optimal range:
- Waist circumference
- Fasting glucose
- HDL cholesterol
- Blood pressure
These five markers are used to make a diagnosis of metabolic syndrome. Metabolic syndrome does not cause high blood sugar, but high blood sugar is one marker of metabolic syndrome. Metabolic health is defined by having all five markers in an optimal range without needing any medications to correct them.
How Does Insulin Resistance Lead to Higher Blood Sugar Levels?
When blood glucose is too high, a healthy pancreas releases insulin.
Insulin has the following effects on body cells:13
- Increases glucose uptake into skeletal muscle and fat cells
- Increases glucose uptake into the liver to be stored as glycogen
- Suppresses the conversion of fats and amino acids to glucose in the liver
- Suppresses the breakdown of fat in adipose tissue
- Suppresses glucagon release from the pancreas
When fat, muscle, and liver cells become insensitive to insulin, the pancreas works harder to pump out more insulin. Eventually, the insulin-producing cells in the pancreas will burn out as they cannot keep up with the demand. As a result, blood glucose levels rise, inflammation increases, and when the pancreas can no longer compensate, type 2 diabetes develops.
How Diet, Exercise, and Body Weight Impact Metabolic Health and Blood Sugar
Muscle cells absorb the majority of excess blood glucose, as long as they are sensitive to insulin. When muscle cells become inflamed from excess fatty acids, the liver picks up excess glucose. If glycogen stores are full, excess glucose in the liver is stored as fat. Free fatty acids increase in the blood, which makes the liver and muscle more insulin resistant.14
Diet, exercise, and body weight all impact metabolic health and metabolism. Since diet and exercise affect body weight and blood sugar, it is important to work on all three as you journey towards better metabolic health.
Dietary Tips to Improve Metabolic Health and Blood Sugar
A healthy diet can reduce post-meal glucose spikes. Dietary tips for better glucose control:14-17
- Choose carbohydrates with a low glycemic index and a low glycemic load.
- Consume high fiber, low carbohydrate foods.
- Consume a diet with 30% of calories from protein, as protein can moderate the glycemic response to carbohydrates, and protein can help with weight loss.
- Moderate or quit alcohol consumption. Alcohol contributes to weight gain because it is high in sugar and calories.
- Reduce dietary saturated fats as they increase inflammation and insulin resistance.
- Choose foods high in magnesium, chromium, and zinc as they reduce insulin resistance.
- Avoid highly processed foods.
- Drink plenty of water to stay hydrated and reduce blood sugar spikes.
- Ensure you get plenty of vitamins and minerals that support weight loss, including B vitamins and magnesium.
<p class="pro-tip"><strong>Learn more about </strong> <a href="/blog/fiber-for-metabolic-health">how fiber supports metabolic health</a>.</p>
Exercise Tips to Improve Metabolic Health and Blood Sugar
Exercise reduces stress, improves insulin sensitivity, and helps with weight management. Even walking can help with weight loss.
The American College of Sports Medicine (ACSM)18 and the U.S. Department of Health and Human Services Physical Activity Guidelines19 jointly recommend the following:
- Exercise at a moderate intensity for 30 minutes a day, five days a week, for a total of 150 minutes of exercise per week.
- Exercise at a vigorous intensity for a minimum of 20 minutes, three days per week, for a total of 60 to 75 minutes per week.
- Do a combination of moderate and vigorous-intensity walking.
Weight Management Tips to Improve Metabolic Health and Blood Sugar
Even small amounts of weight loss can improve your metabolic health and blood sugar. Weight management tips:20,21
- Manage stress to reduce cortisol levels.
- Get 7 to 8 hours of restful sleep, as sleep deprivation contributes to insulin resistance.
- Track servings and calories for a few days to get a feel for the number of calories consumed each day.
- If you are carrying excess weight, aim for a 5% to 10% weight loss.
- Eat mindfully. Eating when distracted leads to underestimating caloric intake.
- Keep healthy foods visible and easy to access.
If you can only improve in one of these areas, start with your diet. You can't out-exercise a bad diet. Learn more in this podcast with Nicole Aucoin from Healthy Steps Nutrition.
Track your progress towards better metabolic health and blood sugar using a continuous glucose monitor (CGM).
<p class="pro-tip"><strong>Keep reading about: </strong> <a href="/blog/the-8-best-foods-for-metabolic-health">the best types of food for metabolic health</a>.</p>
Topics discussed in this article:
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- Nakrani MN, Wineland RH, Anjum F. Physiology, Glucose Metabolism. StatPearls. StatPearls Publishing Copyright © 2022, StatPearls Publishing LLC.; 2022.
- Gancheva S, Jelenik T, Álvarez-Hernández E, Roden M. Interorgan Metabolic Crosstalk in Human Insulin Resistance. Physiological Reviews. 2018;98(3):1371-1415. doi:10.1152/physrev.00015.2017
- LaPelusa A, Kaushik R. Physiology, Proteins. StatPearls. StatPearls Publishing Copyright © 2022, StatPearls Publishing LLC.; 2022.
- Biolo G, Maggi SP, Williams BD, Tipton KD, Wolfe RR. Increased rates of muscle protein turnover and amino acid transport after resistance exercise in humans. Am J Physiol. Mar 1995;268(3 Pt 1):E514-20. doi:10.1152/ajpendo.1995.268.3.E514
- Paddon-Jones D, Sheffield-Moore M, Cree MG, et al. Atrophy and impaired muscle protein synthesis during prolonged inactivity and stress. J Clin Endocrinol Metab. Dec 2006;91(12):4836-41. doi:10.1210/jc.2006-0651
- Kreher JB, Schwartz JB. Overtraining syndrome: a practical guide. Sports Health. Mar 2012;4(2):128-38. doi:10.1177/1941738111434406
- Achten J, Jeukendrup AE. Optimizing fat oxidation through exercise and diet. Nutrition. Jul-Aug 2004;20(7-8):716-27. doi:10.1016/j.nut.2004.04.005
- Nedeltcheva AV, Scheer FA. Metabolic effects of sleep disruption, links to obesity and diabetes. Curr Opin Endocrinol Diabetes Obes. Aug 2014;21(4):293-8. doi:10.1097/med.0000000000000082
- Maciak S, Sawicka D, Sadowska A, et al. Low basal metabolic rate as a risk factor for development of insulin resistance and type 2 diabetes. BMJ Open Diabetes Research &amp; Care. 2020;8(1):e001381. doi:10.1136/bmjdrc-2020-001381
- Johnstone AM, Murison SD, Duncan JS, Rance KA, Speakman JR. Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine. Am J Clin Nutr. Nov 2005;82(5):941-8. doi:10.1093/ajcn/82.5.941
- Engin A. The Definition and Prevalence of Obesity and Metabolic Syndrome. Adv Exp Med Biol. 2017;960:1-17. doi:10.1007/978-3-319-48382-5_1
- Gepstein V, Weiss R. Obesity as the Main Risk Factor for Metabolic Syndrome in Children. Review. Frontiers in Endocrinology. 2019-August-16 2019;10doi:10.3389/fendo.2019.00568
- Govers E, Slof E, Verkoelen H, Hoor-Aukema NM. Guideline for the Management of Insulin Resistance. vol 1. 2015.
- Kim SH, Reaven GM. Isolated Impaired Fasting Glucose and Peripheral Insulin Sensitivity: Not a simple relationship. Diabetes Care. 2008;31(2):347-352. doi:10.2337/dc07-1574
- Wilcox G. Insulin and insulin resistance. Clin Biochem Rev. May 2005;26(2):19-39.
- Simpson RW, McDonald J, Wahlqvist ML, Atley L, Outch K. Macronutrients have different metabolic effects in nondiabetics and diabetics. The American Journal of Clinical Nutrition. 1985;42(3):449-453. doi:10.1093/ajcn/42.3.449
- American College of Sports Medicine. Trending Topic | Physical Activity Guidelines. Accessed July 21, 2022. https://www.acsm.org/education-resources/trending-topics-resources/physical-activity-guidelines
- U.S. Department of Health and Human Services. 2008 Physical Activity Guidelines for Americans. Accessed July 21, 2022. https://health.gov/sites/default/files/2019-09/paguide.pdf
- Cappuccio FP, Miller MA. Sleep and Cardio-Metabolic Disease. Curr Cardiol Rep. Sep 19 2017;19(11):110. doi:10.1007/s11886-017-0916-0
- Donga E, van Dijk M, van Dijk JG, et al. A Single Night of Partial Sleep Deprivation Induces Insulin Resistance in Multiple Metabolic Pathways in Healthy Subjects. The Journal of Clinical Endocrinology & Metabolism. 2010;95(6):2963-2968. doi:10.1210/jc.2009-2430