Diet vs. Exercise for Weight Loss

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As we reported a few weeks ago, recent research has shown that any kind of exercise can help people with diabetes improve their blood glucose control. Now, a new study has shown that diet and exercise can be equally effective at stimulating weight loss and improving Type 2 diabetes risk factors. However, data from the same study also shows that dieting without exercise can increase a person’s risk of bone loss.

The study, conducted by researchers from Washington University School of Medicine in St. Louis, Missouri, looked at a group of about 50 overweight (but not obese) men and women, average age 57, who did not exercise regularly but were otherwise healthy. The researchers divided these men and women into three groups: a calorie-restriction (diet) group that ate less but did not exercise; an exercise group that continued to eat its normal amount of calories but engaged in exercise (such as brisk walking) for about an hour most days; and a control group that received healthy lifestyle advice.

The first set of study results, published in the November issue of the American Journal of Clinical Nutrition, showed that after one year the diet and exercise groups lost similar amounts of weight and body fat and experienced similar improvements in glucose tolerance and insulin action (thereby lowering their risk for Type 2 diabetes) compared to the control group. The researchers concluded that losing weight through dieting and losing weight through exercise appeared to be equally effective methods of improving diabetes risk factors in middle-aged adults.

However, another analysis of the same study participants, published in the December 11/25 issue of the journal Archives of Internal Medicine, showed that the men and women who lost weight through diet but did not exercise also lost bone mineral density at the hip and spine, raising their risk for osteoporosis and fractures. The control group did not experience bone
loss—nor did exercise group, even though it experienced a similar amount of weight loss to the diet group.

These results led the researchers to conclude that it is important to combine exercise with diet to experience weight loss without losing bone. Exercise is believed to protect against bone loss by producing a “healthy” strain on the bones that stimulates them to produce new tissue. The researchers also emphasized that exercise provides other benefits, such as muscle strength and cardiovascular fitness, that cutting calories alone cannot.

For more information on osteoporosis, bone health, and diabetes, please see the article Boning Up on Bone Health.

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