NCPA - National Center for Policy Analysis


November 15, 2005

Much of what passes for obesity science has a large element of junk science in it, says author John Luik. However, at the recent North American Association for the Study of Obesity (NAASO) conference, Luik discovered several studies that provide a bit of balance in understanding just what might be driving weight gain in Americans.

One study looked at the frequent claim that school vending machines are responsible for making kids fat and should be banned. Based on 552 high school students, researchers found:

  • The most frequently purchased item from a vending machine was not soda pop, but water, purchased by 36.3 percent of the young people; this was followed by sweetened beverages other than pop, and purchased by 31 percent.
  • The frequency of purchases from vending machines did not make a difference to the student's calorie intake or to their body mass index.

Another popular obesity claim is that portion sizes offered by restaurants make people fat. Indeed, some fat activists have even called for the government to regulate portion size. Researchers tested the claim that large portions lead people to eat more food and found:

  • Participants who received large portions did not eat more food than participants who received small portions, even though their portion contained five times more food.
  • Portion size made no difference in the amount of food consumed nor did the availability of extra food influence total consumption.

Luik says neither of these studies should come as a surprise for they confirm a considerable amount of previous research about students, vending machines, soft drinks and fast food restaurants. Even though these studies did not make the front page headlines, they are worth understanding since they confound so much of contemporary wisdom about what to do about obesity.

Source: John Luik, "Some Rare Good News on the Obesity Front," Tech Central Station, November 8, 2005.

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