Effects of cardiac stress during a very-low-calorie diet and exercise program in obese women

To assess the safety of very-low-calorie diets (VLCDs), stress tests known to induce arrhythmias in susceptible patients were performed in 24 obese women on a VLCD (660-720 kcal/d) for 6 wk. Half of the subjects had diet only (DO) and half underwent supervised exercise (DE) four times weekly. Five control subjects ate a balanced, moderately low-calorie diet (~1400 kcal/d). Stress tests included maximal and submaximal (85%) exercise, psychological stress, and isometric handgrip tests, all with constant electrocardiogram (ECG) monitoring. Twenty-four-hour Holter monitors at weeks 0 and 6 and weekly resting ECGs were obtained. DO and DE lost similar amounts of weight. There were no changes in QT intervals or in voltage or width of the QRS complex on resting ECG and no arrhythmias on Holter monitoring. These data support the safety of VLCDs containing ≥650 kcal/d and adequate amounts of high-quality protein, vitamins, and minerals for use for periods of at least 6 wk in normal, healthy obese women.