Scientists compared two types of exercise to see which one works better for people struggling with weight and blood sugar control. They studied obese mice doing either running on wheels (like cardio) or weightlifting (like strength training) for 8 weeks. The surprising result: weightlifting was better at improving how the body handles blood sugar and insulin, even though running had some benefits too. This research suggests that if you’re dealing with obesity or diabetes risk, strength training might be more effective than just doing cardio alone.

The Quick Take

  • What they studied: Whether running or weightlifting is better at reducing body fat and improving how the body controls blood sugar in obese mice
  • Who participated: Male mice divided into groups: some ate normal food and stayed sedentary, some ate high-fat food and stayed sedentary, some ate high-fat food and ran on wheels, and some ate high-fat food and did weightlifting exercises for 8 weeks
  • Key finding: Weightlifting was significantly better than running at improving insulin sensitivity (how well the body uses insulin) and blood sugar control, even though both exercises reduced fat gain
  • What it means for you: If you’re overweight or concerned about diabetes, adding strength training to your routine may help your body handle blood sugar better than cardio alone. However, this was a mouse study, so results may differ in humans—talk to your doctor before starting any new exercise program

The Research Details

Researchers took male mice and divided them into four groups. One group ate normal food and didn’t exercise (the healthy control group). Three other groups ate a high-fat diet to make them obese. Of these three groups, one stayed sedentary (no exercise), one ran on wheels voluntarily (endurance exercise), and one did weightlifting exercises (resistance exercise). All groups were studied for 8 weeks, and researchers measured changes in body fat, muscle, exercise ability, heart function, and how well their bodies controlled blood sugar and insulin.

The researchers used special imaging (EchoMRI) to measure exactly how much fat and muscle each mouse had. They also tested how long mice could run before getting tired, and they measured blood sugar control using standard tests called glucose tolerance and insulin tolerance tests. These tests show how well the body handles sugar and insulin.

This study design is important because it directly compares two different types of exercise in the same conditions. Most previous research looked at these exercises separately, so we didn’t know which one was actually better. By testing them side-by-side in obese mice, researchers could see the real differences. This type of comparison is valuable before testing in humans because it helps scientists understand which exercise approach might work best for people with obesity and blood sugar problems.

This study was published in a respected sports and health science journal, which means it went through expert review. The researchers used standard scientific methods and measurements that other scientists use, making the results comparable to other studies. However, because this was done in mice, not humans, the results may not directly apply to people. Mice have different bodies and metabolisms than humans, so we need human studies to confirm these findings.

What the Results Show

Both running and weightlifting helped reduce weight gain compared to mice that didn’t exercise, but they worked differently. Weightlifting was significantly better at reducing both types of body fat (the fat under the skin and the deeper belly fat). Running, on the other hand, increased brown fat (a special type of fat that burns calories and produces heat), which weightlifting didn’t do.

The most important finding was about blood sugar control: weightlifting showed significantly better results than running at improving insulin sensitivity and glucose tolerance. This means the mice doing weightlifting had better control over their blood sugar levels and their bodies responded better to insulin. This is especially important because poor insulin sensitivity is a major problem in obesity and type 2 diabetes.

Interestingly, running improved the mice’s exercise capacity—they could run longer before getting tired. However, this better fitness didn’t translate to better blood sugar control. Weightlifting didn’t improve exercise capacity in the same way, but it still improved blood sugar control more effectively.

Running led to more muscle weight gain in the high-fat diet mice compared to sedentary mice, but weightlifting didn’t show this same muscle growth. Neither exercise type significantly changed how well the heart worked or how strong the leg muscles contracted. Both exercise types successfully reduced fat accumulation, but through different mechanisms—weightlifting reduced overall fat storage while running increased brown fat.

Previous research has shown that both endurance exercise (like running) and resistance exercise (like weightlifting) are good for health, but most studies looked at them separately. This study is one of the first to directly compare them in the same obese condition. The finding that weightlifting is better for blood sugar control is somewhat surprising because endurance exercise has traditionally been emphasized for metabolic health. This research suggests that resistance training may deserve more attention for people with obesity and diabetes risk.

This study was conducted in mice, not humans, so we can’t automatically assume the same results would happen in people. Mice have different body structures, metabolisms, and genetics than humans. The study only looked at male mice, so we don’t know if female mice would have the same results. The study lasted only 8 weeks, which is relatively short, so we don’t know if these benefits would continue or change over longer periods. The study didn’t measure some other important health markers like inflammation or cholesterol levels that might be affected by exercise.

The Bottom Line

Based on this research, if you’re overweight or at risk for type 2 diabetes, incorporating strength training (weightlifting or resistance exercises) into your routine may be particularly beneficial for improving blood sugar control. This doesn’t mean you should ignore cardio—running and other endurance exercise have other important health benefits. The best approach is likely a combination of both types of exercise. However, this is animal research, so talk to your doctor or a certified fitness professional before starting any new exercise program, especially if you have existing health conditions.

This research is most relevant to people who are overweight or obese and concerned about type 2 diabetes or blood sugar control. It’s also interesting for fitness professionals and doctors who recommend exercise programs. People with normal weight and good blood sugar control may still benefit from strength training for other health reasons, but this research doesn’t specifically address their situation. If you have existing heart disease, joint problems, or other health conditions, you should definitely consult your doctor before starting weightlifting.

In the mouse study, significant improvements in blood sugar control appeared within 8 weeks. In humans, you might expect to see improvements in blood sugar control within 4-12 weeks of consistent strength training, though this varies by individual. However, more dramatic changes in body composition and metabolic health typically take 8-12 weeks or longer to become noticeable.

Want to Apply This Research?

  • Track weekly strength training sessions (number of sessions, duration, and exercises performed) alongside fasting blood sugar readings if you have access to them. Set a goal of 2-3 strength training sessions per week and monitor consistency over 8-12 weeks.
  • Add 2-3 structured strength training sessions per week to your routine, focusing on major muscle groups (legs, chest, back, arms). This could be done with weights, resistance bands, or bodyweight exercises. Log each session in the app to maintain accountability and track progress.
  • Track strength training frequency and intensity weekly. If possible, monitor how you feel (energy levels, hunger, mood) and any available health metrics like weight or waist circumference monthly. Note any changes in exercise capacity or how your clothes fit as indirect measures of body composition changes.

This research was conducted in mice and has not yet been tested in humans. While the findings are promising, they cannot be directly applied to human health without further research. If you have obesity, diabetes, prediabetes, or any other health condition, consult with your healthcare provider or a certified fitness professional before starting a new exercise program, especially one involving weightlifting or resistance training. This information is for educational purposes only and should not replace professional medical advice. Always listen to your body and stop exercising if you experience pain or discomfort.