Exercise Provides Added Benefits for Insulin Resistance Beyond Just Weight Loss

Insulin resistance is a growing health concern, as rates of obesity and type 2 diabetes continue to rise globally. While weight loss through diet is known to help improve insulin sensitivity, a new study sheds light on the added benefits of exercise beyond just the scale.

Study Design: obese, prediabetic volunteers

The study recruited obese, prediabetic volunteers and put them on a 25% caloric deficit diet for 5 months, providing all their food to ensure compliance. This led to an average 10% weight loss. The diet was relatively high in carbs (70% of calories) from whole, complex sources like fruits, vegetables and whole grains. The remaining 30% of calories were split between fat and protein.

The participants were divided into two groups:

  • Diet only
  • Diet plus exercise 6 days per week (4 days cardio, 1 day weights, 1 day HIIT)

The aim was to compare the effects of the two interventions on insulin resistance and other metabolic factors.

Results on Body Composition and Metabolic Markers

Both groups lost around 10% of initial body weight, with similar reductions in BMI and body fat percentage. This makes sense given they ate the same hypocaloric diet.

Fasting glucose, insulin, triglycerides, and A1c also improved in both groups, as expected with caloric restriction and weight loss. No significant difference was seen between diet alone and diet plus exercise for these markers.

Diet Plus Exercise Had Greater Improvements in Insulin Sensitivity

Here’s where things get interesting. While the diet alone group increased insulin sensitivity by 48%, the diet plus exercise group improved by 110% – more than double!

Looking specifically at liver insulin sensitivity, the diet alone group increased by 88% versus 160% for diet plus exercise.

Clearly, adding exercise provided significant benefits beyond just the dietary calorie deficit and weight loss.

Potential Mechanisms

What mechanisms could be behind this added benefit of exercise? It doesn’t appear to be changes in body composition. There was no significant difference in fat free mass or lean mass between groups, possibly because strength training was only performed once weekly.

However, the researchers did find differences in gene expression in muscle tissue. Certain genes related to mitochondrial function and blood vessel growth were more active with exercise. While interesting, they did not conclusively show these gene changes actually caused the metabolic improvements.

The exact molecular pathways still need further research. But we can say exercise provides benefits to insulin sensitivity over and above weight loss alone.

Takeaways: Weight Loss vs. Exercise for Insulin Resistance

What can we take away from this study for practical application?

Losing weight through caloric restriction clearly has a huge impact on insulin sensitivity and diabetes risk factors. Exercise alone typically produces more modest weight loss compared to diet changes.

However, this study suggests exercise provides benefits to glucose metabolism and insulin resistance beyond just the number on the scale.

So while monitoring weight is important, exercise may optimize insulin sensitivity through other mechanisms, independent of weight loss.

Both exercise and healthy diet are important tools. Weight loss through calorie control can significantly improve insulin resistance, but adding regular exercise may provide even greater improvements in insulin sensitivity.

Combination of exercise training and weight loss

In obese, prediabetic individuals, the combination of exercise training and weight loss doubled the improvements in insulin sensitivity compared to weight loss alone.

While more research is still needed, these findings suggest exercise confers significant benefits on top of dietary restriction for improving insulin resistance and metabolic health.

So when considering options to reduce diabetes risk, exercise and activity should be considered as an adjunct, not just for aiding weight loss, but for providing added independent benefits to insulin and glucose metabolism.

Both approaches – caloric restriction to reduce weight, and exercise training – can work synergistically to optimize insulin sensitivity and lower diabetes risk.

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