A weight loss calculator is a tool used to estimate the number of calories a person should eat to lose weight. Most such calculators are online applications into which a dieter inputs information such as current weight, age, height, and level of activity. The calculator then uses a formula to determine such values as the Basal Metabolic Rate (BMR). BMR is the minimum number of calories a person expends each day on necessary biological functions such as respiration or the beating of the heart.
Many variations of these calculators exist. The simplest will usually show at least the BMR as an output. Others will calculate Body Mass Index (BMI), expected weight loss on a certain caloric decrease, time needed to reach a weight loss goal, and related values.
Weight loss calculators are among the most common weight loss tools. Most dieters find them a very useful starting point, but some considerations should be kept in mind. First, the values given by a weight loss calculator are approximate. In order to get a truly precise measure of BMR, it is necessary to use specialized equipment through a doctor or other health professional.
Another issue is that using a weight loss calculator often does not dispel the distorted ideas commonly held about weight loss. Most people do not distinguish between types of weight loss. In reality, it is fat loss that should be maximized and muscle loss that should be minimized. Loss of muscle is common on many diets and causes metabolism to drop.
Most weight loss calculators do not take into account the type of calories consumed, merely the quantity. Studies have indicated that calorie type plays a major role in metabolism. For example, rats given high fructose corn syrup gained more weight than rats given sugar, even though both groups of rats had the same caloric intake. Sugary, refined flour foods can raise insulin levels, which retards fat loss.
Anyone using a weight loss calculator should be aware that the amount of weight lost does not always correspond to the number of reduced calories. Eventually, the body tries to hold on to its fat stores by decreasing metabolism. This effect is especially pronounced if caloric intake is too low. Most experts believe that the minimum intake per day should be around 1,200 calories. A very large reduction in calories will retard weight loss and may have undesirable side effects, such as hair loss and irritability.