Although proper nutrition alone can result in weight loss, it does not necessarily correlate with true health or fitness. That's one of the key findings of a study published in the January 2010 issue of the journal Medicine & Science in Sports & Exercise. The study, directed 36 overweight -- but not obese -- adults to participate in one of three programs over a period six months: diet alone, diet plus exercise, or a weight-maintenance program used as a control group.

 The diet-only and weight maintenance groups were told not to change their physical activity regimens during the six-month period. The study sought to determine whether a 25 percent energy deficit that produces equal change in body fatness leads to greater cardiometabolic benefits when aerobic exercise is included. Although both the diet and diet-plus-exercise groups lost weight during the course of the study -- around 10 percent of total body weight -- only those people in the study who exercised improved their internal fitness and lowered their body fat level.

"Results of the current study suggest that beyond changes in fatness, combining CR (caloric restriction) with exercise is important for increasing aerobic fitness and optimizing improvements in risk factors for diabetes and CVD (cardiovascluar disease), including improved insulin sensitivity, LDL cholesterol, and diastolic blood pressure that are beyond those of body weight/body fat reduction alone," the researchers wrote.

Participants in the exercise group performed a structured aerobic exercise -- such as walking, running or stationary cycling -- five days each week for around 50 minutes each session. needs. Participants chose their own exercise type and intensity according to what activities they enjoyed, provided that the intensity level measured between 65 and 90 percent of each participant's maximal heart rate as recommended  in the Amercian College of Sports Medicine's Guidelines for Exercise Testing and Prescription.

"Importantly, our data demonstrate that CR does not lead to reduced overall strength or functionality in humans when fed a nutritionally sound diet," the researchers wrote. "Our results strongly suggest that inclusion of regular aerobic exercise (or training) in a weight loss program yields cardiometabolic health benefits beyond those of weight loss alone. Our results further support the argument that both fitness and fatness are important for reducing cardiometabolic risks, particularly during CR and may shed some light on how fitness or fatness may contribute to overall mortality."

Men in the study used around 500 calories each exercise session and women burned around 400,  averaging approximately 12.5 percent of their daily energy, the report showed.

"Despite similar effect on fat losses, combining CR with exercise increased aerobic fitness in parallel with improved insulin sensitivity, LDL cholesterol, and diastolic BP(blood pressure)," the researchers wrote."The results lend support for inclusion of an exercise component in weight loss programs to improve metabolic fitness." "An interesting question still up for debate is whether improvements in fitness or fatness independently alter risk factors for CVD and the metabolic syndrome, particularly during caloric restriction."

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