Researchers at the Harvard School of Public Health have come up with some interesting data. They analyzed surveys filled out by some 120,000 nurses, physicians, veterinarians and dentists over a period of about twenty years. Starting in the 1980s these subjects answered questionnaires about their diet and weight, including specifics about the number of servings of various foods they consumed per day. Some fascinating revelations have emerged from the massive amount of data collected. First of all, there was an average weight gain of about seventeen pounds over twenty years. Remember, these were educated subjects who presumably knew something about nutrition, yet pounds snuck on roughly at a rate of a pound a year.
Different foods and beverages had different effects. Certain ones had a greater impact on weight gain than others. Over the years some people increased their intake of some foods and decreased the intake of others. Statistical analysis was able to tease out their effects on weight. French fries emerged as the number one villain. One serving a day will result in a weight gain of about a pound and a half a year. Any other type of potato leads to only one sixth as much weight gain. It may seem that this is obvious because the fries contain more fat. However, the data also show that an extra serving of nuts a day actually results in the loss of about a fifth of a pound over a year, despite the nuts being rich in fat. So weight control is more complex than just counting calories. The nuts probably have a greater satiety value and keep people from feeling hungry for a longer time than the fries. As one would guess, eating more fruits and vegetables was associated with weight loss, as were whole grains.
Also, as expected, sugar-sweetened beverages, refined grains, trans fats and potato chips were associated with weight gain. It was also no great surprise that red meat and processed meats put on the pounds. But there was a surprise with dairy products. Whether whole fat or low fat they didn’t have much of an effect. The biggest shock was yogurt. People who ate a serving a day were likely to see a weight loss of a third of a pound over a year. What all of this means is that the usual advice of eating everything in moderation is not the best advice. There are foods to stay away from and foods to try to include in the diet. If you want to control weight, stay away from fries, chips, soft drinks and refined cereals. Minimize red meat and eat plenty of fruits, vegetables and nuts. And of course, do exercise. In the Harvard study the most sedentary put on the most weight. Sleep was also a factor. People who slept less than six or more than eight hours put on the most weight. The more TV people watched the more they gained. Remember that small changes can make a big difference.
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