Calculate your Weight Loss

You must be sick of reading about diets and the fact that they only work for 10% of dieters.

Even with surgery fat can come back.

The US  National Institute of Health and the American Dietetic Association have previously taken the view that weight loss is linked directly to calorie intake – the less you eat the more weight you lose.

So, taking 3,500 calories per pound as the standard rule of thumb, cutting 500 calories a day from your diet should mean that you lose a pound in weight every week.

New research however shows that this doesn’t take into account the ability of your body to adapt to the lower calorie intake by slowing down your metabolism. And of course that rule of thumb means that if you kept going indefinitely you would weigh nothing to speak of – and be dead presumably.

Dr Kevin Hall, an obesity researcher and physicist at the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases, has now come up with a mathematical model which can help people plan their weight loss more scientifically.

He says “This research helps us understand why one person may lose weight faster or slower than another, even when they eat the same diet and do the same exercise. Our computer simulations can then be used to help design personalized weight management programs to address individual needs and goals.”

To test the model, the researchers compared predicted weight changes to actual changes in people. “Mathematical modeling lets us make and test predictions about changes in weight and metabolism over time,” Hall said. “We’re developing research tools to accurately simulate physiological differences between people based on gender, age, height, and weight, as well as body fat and resting metabolic rate.”

For example, the team found that people’s bodies adapt slowly to changes in dietary intake. They also found heavier people can expect greater weight change with the same change in diet, though reaching a stable body weight will take them longer than people with less fat. Typically dieters who lose half their target loss in a year can take another two years until they achieve their target and stabilise.

So the computer simulation, available to use at http://bwsimulator.niddk.nih.gov/, can help you work out how many calories you would have to cut each day to achieve a target weight in a given time period, taking into account your levels of physical activity. And it warns you if you are risking your health in doing that and that you should check with your doctor before dieting.

Source: NIH Press release 25/8/2011

Reference: “Quantifying the effect of energy imbalance on body weight change” was published in the Lancet on Aug. 26, 2011 (http://www.thelancet.com/series/obesity)

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