Dietary measures of physical activity

Area of Science:

• Exercise Physiology
• Nutritional Epidemiology
• Obesity Research

Background:

• Understanding the interplay between energy intake, body composition, and physical capacity is crucial for public health.
• Previous studies suggest a link between caloric intake and body weight regulation, but the role of fitness is less clear.

Purpose of the Study:

• To investigate the relationships between cardiovascular fitness (VO2 max), body fatness, and energy requirements for weight maintenance in obese males.
• To determine if caloric intake adjusted for body weight serves as a valid indicator of habitual physical activity.

Main Methods:

• A controlled feeding experiment involving 21 healthy obese males (aged 20-44 years) over three weeks.
• Measurement of actual caloric intake, body fatness, and maximal oxygen uptake (VO2 max).
• Statistical analysis of correlations between these variables, including comparisons with previous studies.

Main Results:

• Significant inverse correlation found between caloric intake per kg body weight and body fatness (r = -0.79, p = 0.001).
• Significant positive correlation found between caloric intake per kg body weight and VO2 max (r = 0.76, p = 0.001).
• Caloric intake unadjusted for body weight showed no significant relationship with body fatness or VO2 max.

Conclusions:

• Caloric intake adjusted for body weight reflects habitual physical activity in sedentary, obese males.
• The findings support the use of caloric intake per kilogram as a measure of long-term physical activity in epidemiological studies.
• An inverse relationship between caloric intake per kg and mortality may indicate a positive health effect of physical activity.