Type 2 diabetes is a taxing condition that comes with a host of difficult side effects but, unfortunately, there's not one specific cause we can pinpoint. We know this much for sure, though: Weight plays a significant role.
Here, we'll dig into how obesity and type 2 diabetes are connected, how the condition affects weight management and the best ways to combat weight gain if you have the disease.
First, What Is Type 2 Diabetes?
Type 2 diabetes — sometimes called adult-onset diabetes — is a chronic, sometimes fatal disease that accounts for up to 95 percent of all diagnosed cases of diabetes, according to the Obesity Action Coalition (OAC).
People with this type of diabetes don't make insulin and/or aren't able to properly use insulin, a hormone made by the pancreas that helps move sugar into cells from the bloodstream, per the OAC. So the body becomes insulin-resistant, which causes high blood sugar levels. (Those with type 1 diabetes simply stop making insulin altogether.)
Too-high sugar levels can cause damage to nerves and blood vessels, usually in the heart, feet, hands, kidneys and eyes. It can also increase the risk of heart disease, stroke, kidney failure, blindness, erectile dysfunction, depression and amputation.
Some common symptoms of type 2 diabetes include frequent urination, increased thirst, unplanned weight loss, fatigue, blurred vision, dry skin, frequent infections, slow-healing cuts and bruises, and numbness in the hands, legs or feet.
"People who are overweight are three times more likely to develop type 2 diabetes, and those affected by obesity are seven times more likely than someone who is a normal weight."
How Obesity and Diabetes Are Linked
Several factors play a role in the development of type 2 diabetes, including age, genetics, environment and a history of gestational diabetes or polycystic ovary syndrome, according to the Mayo Clinic.
But obesity — defined as a body mass index of 30 or higher — and fat distribution have been found to be the main risk factors.
Indeed, a case study published April 2020 in Diabetologia concluded that obesity and an unhealthy lifestyle were associated with an increased risk for type 2 diabetes regardless of genetic predisposition. And according to the American Society for Metabolic and Bariatric Surgery, more than 90 percent of people with type 2 diabetes are overweight or obese.
"People who are overweight are three times more likely to develop type 2 diabetes, and those affected by obesity are seven times more likely to develop type 2 diabetes than someone who is a normal weight," says Samar Hafida, MD, a weight management and clinical nutrition specialist with the Joslin Diabetes Center and an instructor in medicine at Harvard Medical School.
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The why is a little complicated, but Dr. Hafida breaks it down like this: "Obesity causes a state of chronic inflammation in the body, where immune cells located in the fat tissue produce toxic chemicals that impair insulin's job. These chemicals also cause a state known as lipotoxicity, which harms the body's ability to produce insulin."
Where the fat is located in your body matters, though. Those who have more hard belly fat, also known as visceral fat, tend to have lower insulin sensitivity than those with more subcutaneous fat (the soft, pinchable kind located just under the skin).
"People who have an excess amount of fat also store it in organs such as the liver, pancreas, kidneys and heart," which can damage the functioning of these vital organs, Dr. Hafida explains.
Fat can be stored in our muscles, too. Healthy muscle maintains our bodies' sensitivity to insulin and burns glucose (sugar) for fuel — but when excess fat is stored there, it disrupts the the muscle's ability to do this, she says. "When the body no longer finds a place to store energy, our muscles are forced to become a fat depot, which can severely harm the body's ability to dispose of excess glucose."
Why Type 2 Diabetes Can Cause Weight Loss
One of the early signs of type 2 diabetes is unplanned weight loss — and not just a pound or two. Unexplained weight loss of 10 pounds or more in a short period of time is cause for concern, according to the Cleveland Clinic.
The culprit? Insulin resistance.
"If the body is not able to sensitize insulin, meaning it's not taking glucose from the blood and into the cells to be used as energy, the body will need to find an alternative energy source. It may then turn to utilizing fat and/or muscle as its energy source," explains Maya Feller, RD, CDN, a dietitian who specializes in nutrition for chronic disease prevention. "The net effect is unintentional weight loss."
Feller notes, though, that this is more common when someone has type 1 diabetes.
Does Diabetes Cause Weight Gain?
Strangely enough, type 2 diabetes is also connected to weight gain, and insulin is reason again.
"Because insulin is a growth hormone, insulin resistance can promote weight gain due to the body trying to produce more and more insulin," says Cara Schrager, MPH, RD, LDN, Clinical Programs Manager and Diabetes Educator at the Joslin Diabetes Center.
The scale can also trend upward when someone takes insulin medication — a common treatment for type 2 diabetes when lifestyle changes like diet tweaks and increased exercise fail to keep blood sugar levels in check, per the Cleveland Clinic.
Weight gain can actually be a sign that insulin therapy is working, since your body is using sugar, fat and protein more effectively. Now that your body can store and use these nutrients for energy, taking in excess calories leads to excess fat.
What's more, dehydration is common when type 2 diabetes isn't controlled — a product of the frequent urination mentioned earlier. But when someone starts to manage the condition and their body has a chance to rehydrate, they may notice a few extra pounds of water weight.
Will Losing Weight Help Manage Diabetes?
People with type 2 diabetes can improve their blood sugar numbers by losing 5 to 10 percent of their body weight, according to John Hopkins Medicine.
But dieting is already tough when you don't have a medical condition. Since insulin as well as other medications used to treat diabetes can make it harder to lose the weight necessary to get blood sugar numbers under control, some extra effort may be necessary to get that scale moving in the right direction.
"To reduce the risk of weight gain with diabetes, it is important to manage glucose levels through a healthy diet and exercise," Schrager says.
She recommends meeting with a registered dietitian to come up with a meal plan that's individualized to your lifestyle and needs. But you can also adopt the following healthy guidelines to get you started.
How to Control Your Weight When You Have Diabetes
1. Clean Up Your Diet
Weight loss can only happen if you create a calorie deficit, which means you're burning more than you're taking in. A deficit of 500 to 1,000 calories per day will result in a 1- to 2-pound loss per week, according to the OAC.
People with type 2 diabetes should limit or avoid simple carbs like white bread and pasta, cereal, sugary drinks and desserts because they tend to raise blood sugar levels, which will then in turn produce more insulin and may lead to increased resistance and weight gain.
Foods rich in soluble fiber (think: black beans, broccoli, oatmeal, avocado) are recommended, though, as they may improve glycemic control and decrease hyperinsulinemia. Fiber also keeps you full longer (which means you're less likely to raid the snack cabinet).
2. Add More Exercise
Set a weekly goal to get at least 150 minutes of moderate-intensity physical activity (think: walking, biking, swimming), as recommended by the Centers for Disease Control and Prevention. And on two or more days per week, aim to include strength-training activities that work all your major muscle groups.
3. Ask Your Doctor About Medications
There are some medications that treat type 2 diabetes, insulin resistance and obesity, such as Metformin. Schedule an appointment with your doctor to explore your options.
4. Consider Bariatric Surgery
Bariatric surgery — such as gastric bypass or gastric sleeve — may be an option for people with type 2 diabetes who have a BMI of 35 or higher and have been unable to lose weight with other methods.
A June 2014 article published in The International Journal of Clinical Practice reported that surgery — compared to conventional treatment — results in better blood sugar control, and many patients even go into remission.
"Bariatric surgery has been effective in weight loss and glucose control in individuals with type 2 diabetes. However, with any surgery comes potential complications and risks," Schrager says. "People can still gain weight back after bariatric surgery, so it is important to remember that it involves a lifelong commitment to a lifestyle change."
- Obesity Action Coalition: "Obesity and Type 2 Diabetes"
- Obesity Action Coalition: "Understanding Excess Weight and its Role in Type 2 Diabetes"
- Mayo Clinic: "Type 2 Diabetes"
- Diabetologia: "Obesity, Unfavourable Lifestyle and Genetic Risk Of Type 2 Diabetes: A Case-Cohort Study"
- American Society for Metabolic and Bariatric Surgery: "Type 2 Diabetes and Obesity: Twin Epidemics"
- Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy: "Mechanism linking Diabetes Mellitus and Obesity"
- Cleveland Clinic: "Unexplained Weight Loss? Why You Need to See a Doctor"
- Cleveland Clinic: "My Diabetes Is Controlled — But Why Am I Gaining Weight?"
- Cara Schrager, MPH, RD, LDN, CDE
- John Hopkins Medicine: "Diabetes"
- The International Journal of Clinical Practice: "The Importance of Weight Management in Type 2 Diabetes Mellitus"
- American Diabetes Association: "Blood Sugar and Exercise"
- Centers for Disease Control and Prevention: "Get Active! Living With Diabetes"
- Harvard Health Publishing: "Are You on the Road to a Diabetes Diagnosis?"
- Mayo Clinic: "Hyperinsulinemia: Is it Diabetes?"
- American Diabetes Association: "Elevated Nonesterified Fatty Acids (NEFA) Are Associated with Blunted Hyperglycemia-Induced Increments in Brain Glucose Levels"
- Diabetes Spectrum: "Treatment of Obesity in Patients With Diabetes"