it's whats for dinner While fad diet books slam carbohydrates in praise of protein, there is little scientific evidence to support these claims. The proof of any theory lies in the weight of the scientific evidence. When it comes to claims that pasta is fattening or that the right mix of protein and fat alters metabolism in favor of weight loss, the evidence is sorely lacking.

Repeatedly, studies show that more Americans are overweight today, not because of carbohydrates per se, but because they eat too many calories, often from processed foods high in refined grains, fat, and/or sugar. And, of course, they exercise too little. (Keep in mind that a century ago the definition of a sedentary lifestyle was one where a person was intensely active for less than three hours every day! Now we praise ourselves if we exercise for 30 minutes three times a week.)

When people lose weight on high-protein or low-carbohydrate fad diets, it’s because they’ve limited their food intake, which means they cut calories. Most fad diets supply about 1,200 calories or less a day; you’d lose weight on any diet when you eat so few calories. Actually, there is nothing new about these high-protein diets. They cycle around about every 20 years, and leave people no lighter in the long-run, but at higher risk for developing kidney stones and osteoporosis.

In contrast, there are 1,000s of scientific studies spanning decades of research showing that diets rich in real foods – from fruits and vegetables to whole grains, nuts, and legumes –  lower your risk for chronic diseases, are the best way to attain and maintain a desirable weight, maximize athletic performance, and help you live longer and healthier. Unless future studies uncover some hidden dark side to quality carbohydrates (something close to a miracle), these foods will remain some of the best foods in the diet, as long as they are minimally-processed and accompanied by real foods and low-saturated fat choices.

That said, protein does fill us up and keep us feeling satisfied, so including some protein at meals is a good idea. Just don’t go overboard, since every national nutrition survey dating back to the 1960s has repeatedly found that Americans consume too much protein, but not enough of everything else, from vitamin A to zinc.

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