Weight Loss and Portion Sizes
Americans are known for excess, and food
is not excluded. Portion sizes of food are often large and include more
than one serving, which may be contributing to the increased prevalence
of obesity in the country.
Weight Loss Study & Portion Sizes
(1)
One weight loss study, in which experimenters served men increasing portions
of macaroni and cheese, found that participants ate more food when portions
were increased by as little as 27 percent. Although intake increased with
the amount of food presented, ratings of fullness after the meal were
not affected. This suggests that portion size may influence hunger and
the feeling of satisfaction after a meal, according to researchers, because
as more food was offered, it took longer for participants to reach satiation.
Weight Loss Study & Portion Sizes
(2)
Conversely, in another weight loss study researchers manipulated portion
sizes of lasagna and found that men consumed a substantially greater amount
of food only when portion size was at least doubled. These two weight
loss studies show that people responded to both small and large portion
size increases.
Weight Loss Study & Portion Sizes (3)
Previous weight loss studies have shown that when adults serve themselves,
the amount of food taken remained constant and they ate a relatively consistent
amount of food. In the study where participants were served, the amount
of food in the serving dish varied, and participants' intake of food varied.
Researchers hypothesized that portion size would be influenced by who,
experimenter or participant, determined the amount of food on a plate.
Weight Loss Study & Portion Control
& Children
Another recent study showed that when young children were served food,
they consumed about 25 percent more food than when they helped themselves.
It is not clear why the adults and children differed in their responses
to portion size when they served themselves. Researchers speculate that
children may be encouraged to "clean their plates" and therefore
ate more, or that they may have used their own hunger as a guide of how
much food to take when serving themselves. Adult participants, however,
were influenced by portion size even when they served themselves.
Weight Loss Study Conclusion
Researchers note that future weight loss studies should examine whether
specific factors, such as age, food type or packaging, influence a person's
tendency to alter food intake with portion size. Additionally, educating
people on appropriate portion sizes may be effective in the treatment
and prevention of obesity.
Source: American Journal Clinical Nutrition
December 2002
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