Calorie intake is at the heart of losing weight, and everyone was weaned on the idea that cutting back on 500 calories a day, amounting to 3,500 calories a week (the amount a person has to lose to supposedly lose weight) is the secret to achieving weight loss goals. The National Institutes of Health agrees that being more mindful of caloric intake is crucial in losing weight but offers a more accurate method of measuring a person's calorie requirements.

It's called the "Body Weight Planner" (BWP), a calculator developed by Kevin Hall, a mathematician with the NIH. To use the BWP, a person starts out by supplying basic information like current weight, gender, age, height and physical activity level. Users are provided with a guide to help them estimate their physical activity level, with 1.4 representing sedentary and 2.5 being very active.

Next, an individual's goal weight is requested as well as either the number of days they wish to allot to losing weight or the date by which they want to achieve their goal. The BWP will also inquire afterward about the kind of physical activity changes that one would be employing to reach their weight loss goals.

Factoring in all information provided, the BWP then calculates for the number of calories the person will need to eat to maintain their current weight, to reach their goal within the specified time period and maintain the goal weight once achieved.

The BWP, however, has a caloric limit of 1,000 calories a day, stating that nutrient recommendations cannot be met by going below that number. This prompts the user to key in either a higher goal weight or longer time period to achieve the goal, ensuring that all calorie recommendations stay within healthy ranges.

Hall explained that a major problem with cutting back on just 500 calories is that the rule assumes weight loss occurs in a linear fashion over a period of time.

"That's not the way the body responds," he said, adding that one change in the body will result in changes in its other parts.

Realistically, just about half of weight is lost when cutting back on 500 calories a day per week. This means that, instead of losing a pound by reducing caloric intake by 3,500 calories, those seeking to lose weight should aim for 7,000 calories.

It sounds like losing weight just became more challenging, but following a more realistic method means lost weight is likelier to stay lost.

Photo: Alan Cleaver | Flickr