"Health Halo"

This is a good article:

http://www.nytimes.com/2008/12/02/science/02tier.html?8dpc

It illustrates yet another example of how people can become infected
with magical thinking: when they think that a food is 'healthy' they
lose the ability to make accurate judgments.

" 'People who eat at McDonald's know their sins,' Dr. Chandon said,
'but people at Subway think that a 1,000-calorie sandwich has only 500
calories.' His advice is not for people to avoid Subway or low-fat
snacks, but to take health halos into account. "

The more interesting finding is that adding a pack of crackers to a
meal will cause people to reduce their estimate of calories in a meal
if the crackers are labeled 'Trans Fat Free'. The presence of a
'healthy' food somehow made them think that the entire meal would be
less fattening.

Actually, that is not accurate. When I wrote 'people' I should have
written 'Americans'. Foreigners did not make the same mistake.

My mother, a nurse, has told me about a similar, but far more lethal,
mistake that her patients often make. People who have diabetes need
to avoid sugary foods, and their doctors and nurses try to teach them
how to do this. But these people often buy foods that are labeled
'Low-Fat', thinking that it will be healthier. This is exactly wrong.
Processed foods with a 'Low-Fat' label will almost always contain
extra sugar to make up for the loss of the fat. Diabetic people
should be eating foods with more fat and less sugar, but a belief that
'Low-Fat' means 'healthy' causes these patients to harm themselves.

As the article mentions, the root of the problem is food fads, social
conditioning, and lack of basic scientific knowledge. So beware of
the 'Health Halo' and remember that more food will always turn into
more fat.