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Combining exercise with diet could improve weight loss results. Ezequiel Giménez/Stocksy
  • Regular exercise may have significant benefits when combined with weight loss from diet for individuals who are overweight and have prediabetes, according to new research.
  • The study aimed to determine whether exercise offers advantages beyond weight loss achieved through diet alone.
  • The study compared two groups: one following a diet program and exercise training, while the other only following the diet program.
  • The results revealed that the group combining diet and exercise experienced twice the improvement in insulin sensitivity, which is crucial for managing prediabetes, compared to the diet-only group.

In a new study, scientists from the Centre for Human Nutrition at Washington University School of Medicine, St. Louis, Missouri, looked at the effects of regular exercise when combined with a diet program for people who are overweight and have prediabetes.

The researchers measured how sensitive the participants’ bodies were to insulin, which is a hormone that controls blood sugar levels.

The results showed that the group that changed both their diet and exercise habits had twice the improvement in insulin sensitivity compared to the group that only changed their diet.

This means that their bodies were better able to use insulin to control their blood sugar levels.

The researchers also looked at certain genes in the muscles of the participants, finding that the group that changed both diet and exercise had increased expression (activity) of genes involved in making new mitochondria—the energy factories in cells—energy metabolism, and the growth of new blood vessels.

These changes in gene activity indicate that exercise helps improve the overall function and health of muscles.

They found no significant differences between the two groups in terms of certain markers in the blood related to inflammation or the levels of certain amino acids.

In addition, both groups also showed similar changes in the composition of their gut bacteria, which can affect overall health.

The study was published in Nature Metabolism.

Dr. Sergio P Ramoa at Atrius Health, who was not involved in the research, spoke to Medical News Today, explaining that “despite the growing focus and treatment of obesity and diabetes, diabetes-related mortality increased in the first 20 years of the 21st century.”

“The mentality of obesity treatment has changed, with a focus [on] obesity treatment like a chronic disease, such as hypertension or asthma. With social, educational, and therapeutic mentality changing, there has been significant advances in treatment for weight loss and weight maintenance.”
— Dr. Sergio P Ramoa

Dr. Romoa noted that “this article demonstrates why exercise continues to be a pillar of not only weight management treatment but overall health of the community.”

“Exercise should always be used in conjunction with pharmaceutical treatment for persistent lifestyle changes,” he said.

Kelsey Costa, registered dietitian and health research specialist at the National Coalition on Healthcare (NCHC), who was also not involved in the research, agreed, telling MNT that “the study findings imply that combining exercise training with a calorie-restricted diet can enhance insulin sensitivity and metabolic health beyond the benefits achieved solely through diet-induced weight loss.”

“Given what we know about the barriers to exercise in people with obesity, it is essential to understand how effectively this combination of therapies can improve metabolic health,” Costa pointed out.

When a person has prediabetes, their blood glucose levels are consistently high but not yet high enough to develop into type 2 diabetes.

It serves as a warning sign for an increased risk of developing diabetes, but with lifestyle changes, it can often be prevented or delayed.

Exercise improves insulin sensitivity

Dr. Romoa explained that “exercise improves insulin sensitivity through GLUT4, which is the prime insulin-driven glucose transporter.”

“GLUT4 can be seen in muscle and adipose tissue. Based on a person’s diabetic and obesity status, the number of these transporters are altered. They are decreased in adipose tissue, but remain at normal levels in muscle tissue. Because of this, exercise can continue to improve glucose control. Adipose tissue is no longer able to fully modulate blood glucose due to insulin resistance. Exercise will also upregulate GLUT4 levels in the body. All forms of exercise can improve glucose levels, including walking.”
— Dr. Sergio P Ramoa

Costa noted that, according to this study, “exercise enhances insulin-stimulated glucose uptake, likely due to changes in skeletal muscle biology induced by exercise.”

“This encompasses an upregulation of genes involved in mitochondrial energy metabolism and substrate oxidation and an enhancement in mitochondrial content and function. Consequently, the diet plus exercise group experienced a more substantial increase in muscle insulin sensitivity,” Costa explained.

Previous research shows that exercise is highly recommended as a primary treatment for type 2 diabetes.

Moderate to vigorous exercise for 150 minutes per week, combined with dietary and behavioral changes, can prevent, delay, or reverse the disease.

Various types of exercise, including aerobic and resistance training, can control blood sugar levels. High intensity interval training and small bouts of movement throughout the day are beneficial.

Timing of exercise, such as afternoon exercise and exercising after a meal, may offer additional advantages.

Optimal exercise recommendations considering individual factors are still being studied, so working with healthcare professionals is essential for personalized diabetes management.

Costa highlighted “the significance of integrating a calorie-restricted diet with exercise training to enhance metabolic health and physical function.”

“These results are essential for patients and healthcare providers as they help inform tailored weight management approaches. This is particularly relevant given the widespread prevalence of obesity and its associated risks,” she said.

“Although the advantages of exercise are evident, obstacles to physical activity within this demographic often hinder its integration into weight loss programs. Those in the diet plus exercise cohort engaged in 6 hours of resistance training and aerobic exercise per week. However, implementing this regimen in real-world situations can prove challenging, depending on individual lifestyle, health status, and available resources.”
— Kelsey Costa, MS, RDN

“Still,” Costa said, “the results of this study suggest that clinicians should consider ways to incorporate more structured exercise into weight loss protocols.”

“At the same time, public health initiatives must determine ways to make exercise programs more accessible,” she said.