For a long time dietitians have had a rule of thumb saying that a diet eater needs to cut 3.500 calories, in order to lose one pound. However recent studies indicate that you cannot calculate this through a simple formula.

The result of the new studies are that dietists are led astray over long term, and that much bigger changes are needed to gain or lose weight than the formula suggested. E.g. if you add 60 calories of sweets, a cookie, candy or something else to your regular diet each day, that would add six pounds in one year, 60 pounds over 10 years etc. You do not have to be a scientist to know that, that is not how calories work – nonetheless this was the result of the old rule of thumb formula.

New research performed in lab-settings, that compared to the usual research performed by food-diaries that are unreliable as most people are not truly honest, now show that if you take the example above, the person would probably gain 6 pounds during the first year or so, but after that the effect would level off according to pediatrician David Ludwig and nutrition scientist Martijn Katan – the same math applies to weight loss, off course in reverse.

The reason why this new approach is more reliable, is that a body that has declined in weight needs less energy – because the body does not have the same mass, it does not consume as much, therefore if the initial cut in calories done by the weight loss dieter stays at the same level, the effects would level of after a while. It is the same if you try to gain weight, a body with bigger mass after an increase in weight, needs more energy to sustain the weight, and therefore more calories must be added to keep the weight increase going.

This also makes the new formula very difficult to calculate, as more factors are added than just the calorie to pound ratio. What this means is that weight loss when dieting is actually much less than earlier predicted over long term, as the body becomes accustomed with the new calorie intake, therefore the diet should continuingly be fitted to the new weight, as the diet is under way.