Obesity and Metabolism


What is metabolism?

Metabolism is the process your body uses to convert food and beverages into energy. Our bodies use energy constantly for brain activity, circulating our blood, breathing, repairing cells, and all our physical activities. Your metabolism must produce energy when you’re both active and at rest.

What is basal metabolic rate?

Your basal metabolic rate (BMR) is what people mean when they say they have a “fast” or “slow” metabolism. Your BMR is the rate at which your body is using energy. People who are overweight or have more muscle mass burn more calories than thinner people. Their BMR is likely to be fast because part of their extra weight is muscle, which burns more calories.

BMR is determined by your:

  • Age: Muscle mass decreases as you age, which can slow your BMR.
  • Body type: If you are overweight or have more muscle mass, you’ll burn more calories, even while sleeping. This will increase your BMR, not slow it down. 
  • Sex: Men are more likely to have less body fat and more muscle than women of the same weight. This gives men a faster BMR because more muscle mass burns more calories. 

What is metabolic syndrome?

Metabolic syndrome increases your risk of developing several serious health problems, including an increased risk of type 2 diabetes, heart disease, heart attack, and stroke. You may be diagnosed with metabolic syndrome if you have at least three of these conditions:

  • Extra fat around your waist: a waist measurement of more than 40-inches for men; more than 35 inches for women 
  • High cholesterol levels: triglyceride (blood fat) levels over 150
  • Low HDL cholesterol levels:  less than 50 for women; less than 40 for men
  • High blood pressure: higher than 130/85
  • High glucose (blood sugar): over 110


What causes metabolic syndrome?

It is believed to have many contributing factors, but insulin resistance is the underlying cause. Insulin resistance means the body doesn’t properly use insulin to regular blood sugar (glucose). Glucose levels rise because your body is producing more insulin in an effort to lower your glucose.

Insulin resistance is closely linked to eating an unhealthy diet (too many sugars, fats and calories), and not getting enough physical activity.

At least 44% of Americans over age 50 have this dangerous syndrome, but most are unaware of it. It is an increasingly common health problem, especially for adults in their mid-30s. It is more common for men in their 30s than women.

What are the risks for metabolic syndrome?

Risk factors include:

  • Age: risk increases as you age
  • Being overweight: especially extra fat in the waist area
  • Diabetes: risk increases if family members have type 2 diabetes, or if women had diabetes during pregnancy
  • Having diseases: sleep apnea, liver disease, or polycystic ovary syndrome
  • Ethnicity: Hispanic women have the greatest risk 

Does a slow metabolism cause obesity?

No, because “slow metabolism” is very rare. Obesity happens when you eat more calories than your body burns. The extra calories are stored as fat. 

The complex factors that contribute to weight gain include:

  • Eating and drinking too many calories.
  • Not getting enough physical activity
  • Heredity, plus the eating habits you learned from your family
  • Certain medications
  • An unhealthy lifestyle, including not getting enough sleep and having unrelieved stress

How does obesity affect metabolism?

Obesity has numerous effects on the body, both direct and indirect, that can cause dysfunction in many organs and tissues. These complex and not well understood effects vary by age, overall health, and many other factors. 

Obesity affects metabolism by:

  • Causing inflammation and metabolic syndrome: they can, in turn, cause a wide variety of complications, including high blood pressure, atherosclerosis, type 2 diabetes, increased risk for health disease, cancer, liver disease, obstructive sleep apnea, and other problems.
  • Changing how muscles work: potentially causing physical limitations or disabilities related to strength, mobility, and balance.
  • Causing brain reactions: including links to cognitive function decline, dementia, anxiety, depression, and cerebrovascular disease.


What are the symptoms of metabolic syndrome?

Many of the health problems caused by metabolic syndrome don’t have symptoms, such as high blood pressure or unhealthy cholesterol levels. 

One symptom you will notice is a widening waistline. You may also notice the early symptoms of diabetes: increased thirst, urination, and fatigue. Blurred vision is another symptom of diabetes.


How is my metabolism checked?

Your doctor can check your metabolism with a basic metabolic panel (BMP) blood test. A BMP checks your glucose, calcium level, kidney function, and other potential markers for disease. 

Your doctor may also check for other conditions that can cause problems with metabolism and weight: underactive thyroid (hypothyroidism), Cushing syndrome, or polycystic ovary syndrome.


Can metabolic syndrome be treated?

Yes, you can begin “treating” metabolic syndrome immediately by committing to a healthy lifestyle — today and for the rest of your life. The first steps are improving your diet and increasing physical activity.

  • Healthy diets include lots of fruits, vegetables, whole grains, and lower-fat dairy products. Three daily servings of whole grains can improve how your body uses insulin, reducing the risk of metabolic syndrome. Whole-grain foods, along with fruits and vegetables, are more slowly absorbed by the body, helping regulate insulin use. Also reduce saturated fat and salt. 
  • Regular physical activity, along with weight loss, can improve how your body uses insulin and reduce blood pressure. Exercise helps burn fat and lose weight. Aim for 30 minutes of exercise most days of the week that includes aerobic and strength-building.
  • Maintain a healthy weight.
  • Quit or reduce alcohol and smoking.
  • Treat diabetes by keeping your glucose under control. Follow your doctor’s instructions on taking diabetes medications and regular glucose testing.

It’s important to have doctors you trust to help you improve your metabolic health. At Inland Endocrine, we specialize in evaluating and treating diseases caused by endocrine gland issues such as diabetes and metabolic syndrome. 


Mayo Clinic. 2019. Weight Loss. Retrieved June 23, 2021, {https://www.mayoclinic.org/healthy-lifestyle/weight-loss/expert-answers/slow-metabolism/faq-20058480}

Mayo Clinic. 2021. Metabolic Syndrome. Retrieved June 23, 2021,


Zelman, K.M. n.d. Metabolic Syndrome: the Silent Epidemic. WebMD. Retrieved June 23, 2021, {https://www.webmd.com/heart/metabolic-syndrome/features/metabolic-syndrome-the-silent-epidemic}

Uranga, R.M., Keller, J.N. 2019. The Complex Interactions Between Obesity, Metabolism and the Brain. Frontiers in Neuroscience. Retrieved June 24, 2021, 


Cleveland Clinic. 2020. Blood Tests: How’s Your Metabolism? A BMP Can Tell You. Health Essentials. Retrieved June 23, 2021,



Medically reviewed by:

Jodi B. Nagelberg, MD, MHA

Dr. Jodi Nagelberg is an endocrinologist, with board certification in Internal Medicine. She also holds a masters in Health Administration and Policy. She joins TeleMed2U as Endocrinology Director and supports our mission to increase access to healthcare for patients everywhere.

Postgraduate: University of Southern California Sol Price School of Public Policy Los Angeles, CA  Masters, Health Administration and Policy, 2011