Medically reviewed on April 23, 2023 by Jillian Foglesong Stabile, MD, FAAFP. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Diabetes is a health condition that can impede the body’s ability to convert sugar into usable energy to fuel the body. In effect, sugar is not used by the body’s cells and is instead left in the bloodstream, which can negatively impact blood sugar levels. As a result, those with diabetes may experience significant adverse health effects if not managed properly. 
So, what causes diabetes? Obesity risk factors include type 2 diabetes, heart disease, and stroke. That said, if you’re overweight, you must act quickly to manage your health to reduce your risk of diabetes. 
To help you along your journey, we’re exploring the intricate connection between obesity and diabetes.
What is diabetes?
To understand diabetes, we must first look into the digestive system. When we consume food, our body works hard to absorb each of its nutrients, including: 
When the food passes through the digestive system, the digestive juices break down the food particles so that they can be used more effectively by the body. While proteins (like fish and chicken) break up into amino acids and fats (like avocado and red meat) break up into fatty acids and glycerol, carbohydrates break into simple sugars, or glucose. 
These sugars are the body’s main source of energy. When ingested, they’re absorbed by the small intestine, where the sugars then enter the bloodstream.  In response, the pancreas secretes a hormone called insulin. Insulin acts as the carrier that move glucose from the blood and into cells throughout the body, thus fueling the body with the energy it needs. 
That said, two factors related to diabetes can contribute to elevated levels of sugar in the blood and, consequently, weight gain:
- Excess sugar intake – Let’s say your day typically starts with stopping by your local coffee shop for a chocolate-laden mocha and a blueberry muffin. For lunch, you eat a ham sandwich on white bread, coupled with your favorite soda and a cookie for dessert. As you drive back home from work and dread preparing a home-cooked meal, you swing by the closest fast food joint for a burger and fries. Unfortunately, these types of meals are extremely high in sugars and carbohydrates. As a result, insulin works the best it can to convert as much glucose as possible. The excess sugar can then be stored in the liver and muscles as glycogen, which the body will use when it needs a quick boost of energy. However, when these stores become full, any excess blood glucose that you consume is converted into fat. 
- Insulin resistance – A barrage of excess sugar can also make the body resistant to insulin, specifically the muscles, fat, and liver. As a result, blood sugar will begin to rise and the pancreas will work overtime to produce more insulin to, hopefully, eradicate more sugar from the blood. However, if the pancreas fails to produce enough insulin, blood sugar levels will rise and more sugar will turn into fat, leading to weight gain. 
All that said, there are three types of diabetes (type 2, type 1, and gestational diabetes). Type 2 diabetes mellitus occurs as a result of your body’s inability to properly produce or use insulin to break up sugar in the blood (insulin resistance). Over time, this type of diabetes can negatively impact your nerves and blood vessels.1 Fortunately, it’s preventable with the right lifestyle changes. 
Type 1 diabetes, on the other hand, is an autoimmune disease. The immune system will attack and eradicate insulin-producing beta cells in the pancreas. As a result, those with type 1 diabetes will produce very little insulin and will require insulin injections to regulate their blood sugar levels. This type of diabetes is currently not preventable and often occurs in juveniles. 
Accordingly, obesity is a risk factor of type 2 diabetes, but it doesn’t play a role in the development of type 1 diabetes. Rather, risk factors for type 1 diabetes include genetics, age, and geography. 
The connection between obesity and type 2 diabetes
Obesity and being overweight affects nearly two-thirds of the US adult population and is characterized by an excess of fat within the body. It’s most often measured using body mass index (BMI). BMI indicates how much fat is likely present in an individual's body by dividing a person’s weight by their height. 
Those with a BMI of 30 or above are considered obese.
Obese individuals, as well as those who are overweight (a BMI of 25 or above), are often at risk of certain health conditions and weight-related problems, such as: 
- Coronary heart disease
- Breast cancer
- Bowel cancer
- Excessive sweating
- Joint and back pain
Another risk is type 2 diabetes. In fact, obesity is a leading factor in type 2 diabetes—and both obesity and diabetes are risk factors for cardiovascular disease.11 Those with cardiovascular disease experience restricted blood flow and a build-up of fatty deposits in the artery, which can lead to life-threatening blood clots. 
Furthermore, women with a BMI of 30 or higher are 28 times more likely to develop diabetes than women of healthy weights. Similarly, people with a BMI of 35 or higher are 93 times more likely to develop insulin resistance. 
That’s because the body is unable to effectively convert high levels of glucose in the body, which is often disguised as fat.
In addition to insulin resistance, obesity is also associated with other metabolic changes that can increase the likelihood of contracting type 2 diabetes. These include:
- Inflammation – Obesity can predispose individuals to inflammatory responses. More specifically, a build-up of fat in the body can stimulate the release of inflammatory mediators, such as pro-inflammatory cytokines, which call immune cells to sites of infection and trigger fever, tissue destruction, and inflammation.13 Inflammation, plays a key role in the disordered physiological processes of diabetes, since it triggers insulin resistance. Conversely, low insulin sensitivity can also cause inflammation, resulting in a vicious cycle. 
- Oxidative stress – Oxidative stress occurs when there exists an imbalance of free radicals and antioxidants within the body, which is implicated in numerous diseases, including diabetes, since it disrupts and damages cells and cellular pathways. And, unfortunately, obesity can elevate levels of plasma leptin in the body, which can contribute to obesity-induced oxidative stress and lead to inflammation throughout the body. 
- Unhealthy gut microbiome – The gut microbiome can play a large role in the body’s ability to metabolize nutrients and expend energy. In effect, a healthy gut microbiome can increase energy production, provide low-grade inflammation, and reduce fat storage. That said, those who are obese often have higher amounts of bad bacteria in their gut, which can negatively impact the metabolism of glucose, leading to weight gain and obesity.16 An unhealthy gut microbiome is also linked to the onset of type 2 diabetes since it can cause insulin resistance, decreased glucose tolerance, and inflammatory responses throughout the body. 
Causes of obesity
It’s evident that obesity is a leading cause of type 2 diabetes. Accordingly, one way to prevent the onset of diabetes is to manage your body weight to prevent the accumulation of excess fat throughout the body, which can lead to inflammation and insulin resistance.
Having said that, it’s crucial to reduce or prevent certain lifestyle habits that can lead to obesity. Common causes of overweight and obesity include: 
- Sedentary lifestyle – Weight gain is often caused when more calories are consumed than energy is expended. Fortunately, regular physical activity can help facilitate calorie burning and, thus, reduce the risk of developing excess fat deposits in the body. Typically it’s recommended to partake in a cardiovascular exercise 75 to 150 minutes a week and engage in strength training twice a week. 
- Unhealthy diet – A poor diet filled with high amounts of refined carbohydrates, sugars, and unhealthy fats can lead to excess calorie consumption and body weight gain. A healthy diet that is rich in fruits, vegetables, whole grains, lean proteins, and healthy fats can help to prevent obesity and type 2 diabetes risk.18 It’s important in how to maintain weight loss.
- Genetics – Genetics can play a role in obesity. For example, certain genes can cause a disorder called Prader-Willi syndrome. This condition can increase fatigue and muscle loss, which may make individuals more predisposed to gaining body weight and becoming obese. 
- Health conditions – Certain non-genetic health conditions can also contribute to excessive or abnormal weight gain. These include underactive thyroid, Cushing syndrome and polycystic ovary syndrome (PCOS). 
- Medications – Some types of medicine, like corticosteroids, antidepressants, and seizure medicines can also cause weight gain, since they often lead to increased appetite, inflammation, sodium retention, and inefficient metabolism of carbohydrates. 
- Poor emotional state – Oftentimes, those feeling sad or anxious turn to food to ease emotional stress. If they eat too many carbohydrates or sugars in the long-term, individuals may begin to see fat build-up on their bodies. 
- Inconsistent sleep schedules – Sleep deprivation is often linked to obesity since it can contribute to elevated cortisol levels, insulin resistance, and increased blood pressure. 
Monitor your weight and blood glucose levels with Everlywell
Obesity and diabetes are linked: An excess of fat deposits within the body can cause high blood sugar levels and insulin resistance, which can predispose individuals to type 2 diabetes. Fortunately, type 2 diabetes is manageable and largely preventable with the right lifestyle changes.
At Everlywell, we provide an at-home HbA1c Test to monitor your blood sugar levels. You can also enroll in our weight management telehealth program for one-on-one virtual visits with a licensed clinician, who can provide support while you adjust your lifestyle and manage your health.
Take the next step toward overall health with Everlywell.
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