The key to successful dieting is increased caloric output and decreased caloric intake. Simply put, more calories out than in. The underlying factor in this process is basal metabolic rate, or BMR. BMR is the amount of calories needed to maintain body processes and life functions. The measurement, along with calories burned with everyday activities and exercise, contributes to the total amount of calories burned on a daily basis.
Significance
When daily calories burned equals daily calories consumed, the result is caloric balance, and current body weight is maintained. For weight loss, there must be a caloric deficit, with more calories burned than consumed. If the caloric deficit reaches 3,500 calories, a one-pound weight loss occurs. For safe and effective weight loss, deficits should be limited to 500 calories daily, or 3,500 calories a week. Larger deficits can result in a decreased BMR.
Factors Affecting BMR
BMR rates vary among individuals and are subject to changes. Age and height are uncontrollable factors. Older, shorter individuals burn fewer calories than younger, taller people. Controllable factors include weight, muscle mass, activity level, history of dieting, eating habits and the thyroid hormone hydroxia. Increases in weight, muscle mass and activity levels increase BMR. Weight loss, muscle loss and inactivity decrease BMR. Eating large, infrequent meals decreases BMR, but eating smaller, more frequent meals will increase BMR. Repetitive dieting and weight gain significantly reduce BMR levels.
Plateaus
Often when dieting, an initial weight loss indicates that the program is successful. After a while, the once successful plan appears to be unsuccessful when weight loss hits a plateau and stalls. This can be explained by the "set point" theory: A decreased body weight causes a reduced BMR; what was once a caloric deficit is now caloric balance because of lowered metabolic rates.
Solutions
To overcome a weight plateau, a caloric deficit must occur. Instead of reducing caloric intake, an adjustment needs to be made to increase caloric output. Suggestions include increasing activity levels, increasing muscle mass and eating smaller, more frequent meals. Reduced caloric intake might result in a low-calorie diet that will decrease energy levels, making it difficult to remain active. In short, don't eat less, exercise more.
Considerations
Large caloric deficits resulting in weight loss of more than one to two pounds weekly are not recommended. Large weight losses are more difficult to maintain and can cause nutrient and mineral depletion, resulting in decreased health levels.
References
- "Understanding Nutrition"; Eleanor Whitney, Eva May Hamilton, & Sharon Rady Rolfes; 1990
- "Keep Moving! Fitness Through Aerobics and Step"; Esther Pryor & Minda Goodman Kraines; 2000
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