If you’re trying to lose weight and you’re seeing progress with healthy habits, it can feel rewarding. When you see the scale move, it’s usually a sign that your diet and activity changes are working.
But there are times when you can lose weight for reasons that have nothing to do with healthier habits. One example is high blood sugar or diabetes, which can cause your body to burn fat and muscle instead of using sugar for energy.
Jennifer Meyfeldt, MD, an obesity medicine specialist with Banner - University Medicine, shared some ways to tell when your weight loss is healthy and when it could mean something’s not right.
How blood sugar and insulin work
The sugar in your blood (glucose) comes from the foods you eat. Glucose is your body’s main source of energy.
“Insulin is a hormone that works like a key to let sugar from your blood go into your cells. Your cells need sugar for energy, just like a car needs gas,” Dr. Meyfeldt said.
When insulin works the way it should, your blood sugar levels stay within a healthy range.
When your body doesn’t make enough insulin or can’t use it well, the sugar stays in your blood instead of going into your cells. Over time, this imbalance affects your energy, weight and overall health and you can develop diabetes.
Why high blood sugar can cause weight loss
When insulin isn’t doing its job, the body can’t use glucose for energy, even though plenty of sugar is circulating in the blood. “Your body gets hungry for energy,” Dr. Meyfeldt said.
To get the energy it needs, your body starts:
- Breaking down fat and muscle for fuel
- Losing calories through urine as the kidneys flush out excess sugar
When this happens, you can have unexplained or rapid weight loss, even if you haven’t made major changes to how you eat or exercise.
Other signs of high blood sugar
Weight loss is often not the only symptom. Other common high blood sugar symptoms include:
- Having to urinate often
- Feeling very thirsty
“This happens because your kidneys try to get rid of the sugar through your urine and you lose water in the process,” Dr. Meyfeldt said.
You may also notice these symptoms:
- Feeling unusually tired or weak
- Feeling hungry even though you’re eating normally
- Blurry vision
- Dry mouth or itchy skin
- Tingling or numbness in your hands or feet
- Slow healing cuts
- Frequent infections
- Nausea, vomiting or confusion, in more severe cases
Having several of these symptoms at once is a good reason to get your blood sugar checked.
Why this kind of weight loss is easy to miss
Unexplained weight loss can be tricky to spot. Many people assume their new eating habits or activity level are responsible. “If you are trying to lose weight, you may not be surprised or worried about the weight loss right away,” Dr. Meyfeldt said.
Early signs of diabetes can also be mild. “Diabetes can develop slowly, so your body may not notice the change in blood sugar until it gets very high,” Dr. Meyfeldt said.
Weight loss, fatigue, thirst or blurry vision are often blamed on stress, aging, digestive system issues or lack of sleep.
It’s a good idea to talk to your health care provider about any changes in your weight, even if they are small.
When to see a doctor
Consider scheduling a visit if:
- You’ve lost five to 10 pounds or more without trying or with minimal lifestyle changes. “Even in people with extra weight, this can be a sign of a serious medical problem,” Dr. Meyfeldt said.
- You notice fatigue, feeling thirstier than usual or having to urinate often.
- You have risk factors like a family history of diabetes, excess weight, high blood pressure or a history of gestational diabetes.
Get medical care right away if you have nausea, vomiting, fruity-smelling breath or confusion. These can be signs of diabetic ketoacidosis (DKA), a serious condition that needs medical attention immediately.
“If you think you might have high blood sugar but worry about starting a medication for it, don't let this stop you from getting checked out. There are lots of ways your doctor can help you lower your blood sugar and keep you healthy,” Dr. Meyfeldt said.
Tests that can confirm high blood sugar
Several simple tests can help your health care provider see if you have high blood sugar or diabetes and can check for other things that could be causing weight loss:
- A1C test: Shows your average blood sugar levels over the past three months
- Fasting glucose test: Measures your blood sugar after you don’t eat overnight
- Oral glucose tolerance test: Checks how your body processes sugar after a glucose drink
- Other blood tests: Check your blood counts and your kidney, liver and thyroid function
These tests are quick and commonly done during visits with your primary care provider.
“They will also make sure that you are up to date on all recommended cancer screenings,” Dr. Meyfeldt said. That’s because unexplained weight loss could sometimes be a sign of cancer.
Managing high blood sugar
If you’re diagnosed with high blood sugar or diabetes, these steps can help you control your blood sugar so you get your energy back and stabilize your weight.
- Follow a balanced eating plan: Include plenty of vegetables and avoid sugary snacks and drinks
- Get regular physical activity: Move your body for at least 150 minutes per week
- Drink plenty of water: Hydration helps you stay healthy
- Manage stress: Stress can increase blood sugar levels
- Take medications if needed: You may need insulin or other medications, depending on how severe your diabetes is and how well lifestyle changes work
- Stay on top of monitoring: Regular A1C and glucose checks help review your progress.
With the right care, many people see improvements in symptoms, weight and overall health.
Take action today
Even if you’ve been eating better, unexplained weight loss deserves your attention. “If you have high blood sugar, starting treatment as early as possible can lead to a lower blood sugar level long-term and lower your risk of complications,” Dr. Meyfeldt said.
Why choose Banner Health
Banner’s diabetes care team includes endocrinologists, primary care doctors, dietitians and diabetes educators who work together. Whether you need screening, treatment or ongoing support, Banner offers coordinated care tailored to your needs. Find a Banner Health provider near you and get the care you need.
