Tip sheet Annals of Internal Medicine, Sept. 5, 2006

1. Underestimation of Calorie Content is Related to Meal Size Not Body Size

Some think that normal weight people are better able than overweight people to estimate the calorie content of meals. But a new study found that both overweight and normal weight people correctly estimated the number of calories in smaller meals in fast-food restaurants, and both underestimated the calories in larger meals (Article, p. 326).

Since overweight people tend to eat larger meals, underestimation of calories could contribute to excess pounds.

The authors suggest that people trying to lose weight might better estimate their calorie intake by:

  • doubling their initial estimate of calories in a large meal
  • estimating calories item by item (small amounts) instead of estimating for the meal as a whole
  • considering portion-size benchmarks when estimating calorie content, e.g. a portion of meat should be about the size of a deck of cards)

2. Virgin Olive, High in Polyphenols, Reduces Heart Disease Risk Factors

Olive oil is known to be heart healthy because it contains monounsturated fatty acids. Researchers wanted to know if the polyphenols in olive oil also contribute to olive oil's heart-healthy aspects.

Virgin olive oil, which comes from the first pressing of olives, contains higher amounts of polyphenols than refined olive oil, which comes from later pressings.

In a crossover study, 200 healthy young men consumed about one tablespoon of either virgin olive oil, refined olive oil or a mixture of the two types of olive oils each day for three weeks, then switched to another type of olive oil.

The study found that virgin olive oil (high in polyphenols) increased the level of high-density lipoprotein cholesterol ("good" cholesterol) more than the other two types of olive oil. It also increased the body level of substances that prevent oxidation of low-density lipoprotein cholesterol ("bad" cholesterol). (Oxidation makes the LDL more likely to promote blood vessel clots.)

The authors say that the study "provides evidence to recommend the use of polyphenol-rich olive oil, that is, virgin olive oil, as a source of fat to achieve additional benefits against cardiovascular risk factors." (Article, p. 333.)


Last reviewed: By John M. Grohol, Psy.D. on 30 Apr 2016
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