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Does diabetes cause or prevent weight loss?

In most cases, weight loss is high on the list of ways to prevent and manage diabetes. Losing weight improves cardiovascular health, reduces the risk of high blood pressure, maintains blood glucose levels, cuts insulin resistance, and more. But occasionally, primarily in cases of Type 1 diabetes, weight loss can be unexpected, abnormal, and a cause for concern. Fortunately, knowing how diabetes can cause weight loss, what to look for, and when to see a healthcare provider can go a long way in managing the disease and staying healthy.

Can diabetes cause weight loss? 

Yes, it can. Diabetes mellitus reduces the body’s production and/or its response to insulin—a hormone that regulates blood sugar levels by helping the body convert glucose into energy. If cells can’t create or use enough insulin to perform this conversion, they may think the body is starving and begin consuming muscle and body fat for energy instead, causing sudden weight decreases. Most of the time, this occurs in cases of Type 1 diabetes, although Type 2 diabetes can cause unexplained weight loss, too.

Anyone who isn’t making a concerted effort to lose weight but still sees consistent drops when standing on the scale should take note. This type of unexplained weight loss could be a sign of undiagnosed diabetes. It could also stem from a host of other conditions, including thyroid issues, celiac disease, Crohn’s disease, cancer, and more. The only way to know for sure is to visit a healthcare provider.

Studies have shown that certain diabetes medications, like metformin, can also cause and help maintain weight loss over multiple years. Other diabetes drugs that may decrease appetite and cause weight loss include Byetta and Victoza.

When to see a healthcare provider

Sometimes, body weight can fluctuate naturally, so when should someone be concerned? The general consensus is that an unintentional 5% or more decrease in body weight over a six- to 12-month period is abnormal.

“Sudden weight loss can be a sign of rising or uncontrolled blood glucose levels,” says Lisa Moskovitz, RD, the CEO of NY Nutrition Group. “Whether or not you’re intentionally losing weight, any loss greater than two to three pounds per week should be reported to your healthcare provider.”

On the flip side, obesity is a significant risk factor for Type 2 diabetes. People with a body mass index (BMI) of 30 or higher often have a higher level of insulin resistance, potentially leading to Type 2 diabetes. Not every case of obesity leads to diabetes, but it certainly increases the chances of developing it. On top of that, obesity can exacerbate diabetes symptoms for anyone who already has it. 

For this reason, healthcare providers and dietitians will often develop diets or weight loss programs for patients with diabetes or prediabetes. These programs often include meal plans and physical activity routines that help patients achieve and maintain a healthy weight, reducing the risk or severity of Type 2 diabetes. Typically, this involves analyzing the patient’s current eating and exercise habits, then laying out practical lifestyle changes that will help achieve personal weight loss goals.

RELATED: Overweight and obesity statistics

How to safely lose weight when you have diabetes

Even though people with diabetes can experience sudden, unexplained weight loss, this isn’t the most common outcome. It mainly occurs in Type 1 diabetes cases, which only comprise 5% to 10% of all diabetes cases. More often, it’s the opposite—losing weight is a struggle. Insulin resistance leads to higher insulin levels, which can increase hunger and overeating. And during insulin therapy, the body stores more glucose as fat. Both situations can lead to weight gain or, at least, more difficulty with weight management. 

While there’s no cure for Type 2 diabetes, sustained weight loss through dieting and physical activity can reverse it (the actual amount of weight needed varies). This doesn’t mean that diabetes is gone forever. It simply means that the disease is in remission, and the patient is maintaining healthy blood sugar levels, but symptoms could always return. 

The biggest question is: What’s the best, safest way to lose weight if you have diabetes? There are plenty of fad diets that aren’t healthy. Sure, consuming nothing but carrot juice for a week will probably help lose weight, but it’s probably not the healthiest option in the long run. It’s often better to eat a personalized, well-rounded diet, manage portions, and exercise regularly. Here are some diabetes weight loss options that might be more effective:

  1. Low-calorie diets: This is a time-tested weight loss approach. A calorie deficit day after day will lead to weight loss. Typically, this limits caloric intake to 1,200 to 1,600 a day for men and 1,000 to 1,200 a day for women. But it’s also about eating the right calories—a balanced diet with enough vegetables, fruits, protein, and carbohydrates. A study from the U.K. showed that 45.6% of people with Type 2 diabetes who participated in a low-calorie weight management program achieved remission within one year.
  2. Very low-calorie diets (VLCDs): VLCDs are a more recent trend restricting the patient to less than 800 calories per day. It’s difficult, but in a 2019 study, diabetes patients on a less-than-600-calorie per day VLCD showed “rapid improvement in glycemic control” in just two weeks, and 79% achieved remission in eight to 12 weeks. 
  3. Avoiding certain foods: Specifically, healthcare providers might recommend drastically reducing or cutting out processed grains, full-fat dairy products, foods high in saturated or trans fats, and foods with added sugar or sweeteners. These foods can cause spikes in blood sugar and increase fat intake. 
  4. Portion control: This one is pretty self-explanatory. Overeating can lead to weight gain, which is detrimental to diabetes care. To help keep patients on track, dietitians often create a balanced meal plan to reduce sugar and fat intake while teaching healthy eating habits.
  5. Regular exercise: Exercise can lower blood sugar and increase insulin sensitivity for up to 24 hours after a workout. However, this depends on the workout’s intensity and duration, according to the American Diabetes Association (ADA). Healthcare providers might create an exercise routine to pair with a patient’s meal plan when treating diabetes. 

That said, diabetes “can wreak havoc on one’s relationship with food,” says Moskovitz. “It is not uncommon to develop disordered eating patterns or even eating disorders after diagnosis. For that reason, a personalized, flexible, and inclusive approach that fits the individual’s needs and lifestyle is paramount for long-term success.”

Moskovitz recommends “a low glycemic diet with plenty of plant-based and fiber-rich foods, lean proteins, and anti-inflammatory fats, [which] is the best treatment to regulate hemoglobin A1C, the average blood sugar over the course of three months.” She advises that people with diabetes should consume alcohol and caffeine in moderation (since they can both impact blood sugar levels) and eat balanced meals or snacks consisting of fiber, protein, and fat every three to five hours throughout the day.

What about low-carb diets?

Low-carb and zero-carb diets have been hot for the past several years. Thousands of people have jumped on (and sometimes off) the Atkins Diet and keto diet bandwagons. Some people swear by them, even though certain studies have shown the long-term hazards of cutting out an entire macronutrient.

When it comes to diabetes, “carbohydrate counting can also make weight loss easier and more effective,” says Moskovitz. But while carb counting is often helpful, eliminating carbs isn’t always the best long-term option. It’s more about eating the right type of carbohydrates in the right amounts. Refined, enriched carbs like white bread, baked goods, and sugars can cause quick spikes in blood glucose. Complex carbs and fibers from whole grains, fruits, and vegetables take longer to break down, preventing a spike.