I agree. Exercise has an independent effect.

My understanding is that the 5-10% guideline wasn’t established because people couldn’t maintain more, but because research was done to determine the minimal amount of weight loss necessary to improve health. That said, we now know (thanks to Dr. Robert Ross) that health markers can be improved without ANY weight loss if moderate exercise is performed.

Whether people CAN physiologically keep the weight off and whether they are willing to do the work required to do so are two different issues.

“Classically, a genetic contribution to a human
trait is quantified by comparing the trait’s
variation between identical and non-identical
twins. Using this approach, the heritability
of obesity — percentage of variation
due to genetic factors — ranges between 70%
and 80%. These values exceed those for most
other traits that are commonly accepted to
have a biological basis, including diabetes,
heart disease and cancer. Indeed, the only
trait with consistently higher heritability
than obesity is height.

Now they usually call it a settling point concept instead of a set point. And the 5-10% is reasonable, though a 40lbs loss for a morbidly obese will still leave them in that category. We are now slowly accepting the 5-10% as a good number because we know there is a huge genetic factor and is almost impossible to get people to normal BMI levels and keep them that way.

Other general info about obesity not to forget:
Physiologically, once fat cells have developed they can no longer be destroyed without outside interference. That is, changes in body fat come from losses in fat cell size, not number. Thus, an obese child steps into the adult life with a proportionally larger number of fat cells, which forcibly need to always be minimally stocked, than the average child (knowing that fat cell hyperplasia can occur more significantly at certain times, like puberty for example).

Cheers,

@ Alejandro – I totally agree that being overweight or obese is a symptom of something else. While behaviours like eating excess calories and lack of activity can make someone obese, I think the real key is to find out WHY the person overeats or is inactive. Various factors can influence these behaviours and addressing these will treat the cause. Performing surgery without addressing the cause often results in weight regain or other destructive behaviours including suicide.

@ Stephen – I agree that the biggest issue with childhood obesity is knowing when it actually exists. Even in adults doctors rarely write the diagnosis of obesity in their medical charts. If something is not documented as a problem what do you think are the odds it is being treated?

The “number to treat” data came from a guy who has studied a 15,000 person sample at his clinic so his sample is fairly representative of this population. Although stats don’t work exactly as he proposed, I would suggest that he’s possibly on the right track.

@ Anoop – I’m not really a fan of the metabolic set point argument for body weight (especially if someone is morbidly obese). If someone is 400 pounds it should be actually really easy to lose and maintain a 10% (40 pound) weight loss. And if there is a set point, when is it determined? And by what? Genetics certainly can’t account for everyone who is overweight and obese.