Is a Calorie Just a Calorie?

The Washington Post had a very interesting article yesterday about weight gain and loss, “Potatoes Bad, Nuts Good for Staying Slim, Harvard Study Finds.” This article discusses a 20-year research project that followed more than 120,000 U.S. men and women in their 30s, 40s, and 50s for four-year intervals to see how changes in what they ate, drank, and did affected their weight.

Programs like Weight Watchers assume that “a calorie is a calorie” no matter where it comes from, but this study suggests that this assumption isn’t accurate.  The article has a terrific graphic that demonstrates the impact of an additional serving of a variety of foods, including meats, potatoes, vegetables, dairy, diet soda, fruit juice, etc. 

Here is a highlight of results that interested me as a dieter.  Please note that the study refers to additional and extra servings above and beyond what the researchers considered as a daily portion.  What “daily” constituted was not stated in the article; however, you can go to the USDA website for the new, 2011 food guidelines, “Choose My Plate,” and search a food to find out what is appropriate for a person of your age.

Potatoes: Every additional serving of potatoes that people added to their regular diet each day made them gain an average of 3.35 pounds over the four years.  The type of potato was important. Every order of french fries put on 3.35 pounds; a snack of potato chips added 1.69. But even each helping of boiled, baked or mashed potatoes contributed a little more than a half-pound…Although the study did not evaluate why potatoes would be particularly fattening, other research shows that starches and refined carbohydrates such as potatoes cause blood sugar and insulin to surge, which makes people feel less satisfied and eat more as a result.

Refined Grains: Every extra serving of refined grains, such as white bread, added 0.39 pounds over four years — almost as much as indulging in some sweets or desserts.

Milk: The difference between the weight gain/loss of people who drank an additional serving of low-fat milk versus those who drank whole-fat milk was negligible over the four-year period.

Fruits and Vegetables: Every added serving prevented between a quarter- and a half-pound gain over four years.

Nuts: Every extra serving prevented more than a half-pound of weight gain over four years.

Yogurt: Every additional serving kept off nearly a pound over four years.  Researchers speculate that this may be because of subtle shifts of microbes in the digestive tract, or perhaps because people who eat more yogurt also tend to do other healthy things. 

Many thanks to friend and reader, Sharon, for bringing my attention to this article.


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