Physiologic changes after diet combined with structured aerobic exercise or lifestyle activity

Area of Science:

• Exercise Physiology
• Metabolic Health
• Weight Management

Background:

• Lifestyle activity may aid weight management, but its impact on physiological variables compared to vigorous exercise is unclear.
• Understanding metabolic changes during weight loss with moderate versus vigorous activity is crucial for public health recommendations.

Purpose of the Study:

• To compare changes in resting metabolic energy expenditure (REE), fat mass (FM), and fat-free mass (FFM) between diet plus aerobic exercise (AER) and diet plus lifestyle activity (LIFE) groups.
• To determine if vigorous aerobic exercise offers advantages over lifestyle activity in preserving REE during caloric restriction.

Main Methods:

• 39 overweight adults were randomized into diet plus AER (vigorous, 3-4 days/week) or diet plus LIFE (moderate, most days/week) for 12 weeks.
• Both groups followed a reduced-calorie diet (1200-1800 kcal/day).
• REE, FM, and FFM were measured before and after the intervention using open-circuit spirometry and body composition analysis.

Main Results:

• Both AER and LIFE groups achieved significant weight loss (8.4% and 6.7%, respectively).
• Both groups experienced similar reductions in REE (10.9% for AER, 10.2% for LIFE) and no significant differences in changes to FM or FFM.
• Changes in REE were not correlated with changes in FFM or FM in either group.

Conclusions:

• Diet combined with lifestyle physical activity is an effective alternative to vigorous aerobic exercise for weight loss in adults.
• Lifestyle activity does not lead to greater reductions in resting metabolic energy expenditure compared to vigorous aerobic exercise when combined with a calorie-restricted diet.
• Moderate intensity lifestyle activity is a suitable option for individuals finding adherence to vigorous exercise programs challenging.