Diet vs. Exercise: A Verdict is Reached

A recurring question in the realm of health, nutrition and weight loss is whether it is diet or exercise that is primarily responsible for progress. It now appears that the question has been resolved—and the answer is “yes”. A team of researchers has reported that a combination of diet and exercise yielded marked improvement in physical function and weight loss as compared with either approach performed on its own.

In a one-year randomized controlled trial, researchers examined 107 adults over the age of 65—all were classified as obese according to BMI measurement. Patients were randomly assigned to one of four groups: control (no behavioral changes), diet-only, exercise-only and combined diet-exercise.

Results were judged by a number of factors, including any improvements made in a modified version of the Physical Performance Test, measurements of body composition, assessments of frailty and reports on quality of life. Collectively, accumulated data demonstrated that blood pressure, waist circumference, abdominal fat, serum triglycerides and C-reactive protein were seen to improve in both the diet and the diet-exercise groups.

Researchers also found that body weight was reduced by 10% in the diet group and by 9% in the diet-exercise group; this is a possible indication that some degree of muscular growth had occurred in the group that was both dieting and exercising. There was no change in bodyweight reported in the control group, who made no changes in lifestyle—needless to say, an expected result.

Researchers summarized the more relevant findings as follows: “Diet-induced weight loss with or without exercise, but not exercise training alone, improves insulin sensitivity and multiple other cardiometabolic risk factors simultaneously in obese older adults. However, the combination of these interventions is associated with an even greater improvement in insulin sensitivity.”

Interestingly, there was no measureable decrease in the exercise-only group regarding body weight either. While this lends some support to the widely-held belief that a poor diet cannot be “out-exercised”, it is important to remember that the diet-exercise group still experienced the greatest overall benefits, indicating that physical exercise makes an excellent addition to a proper diet.