This 12-month trial followed over 300 overweight and obese premenopausal women, randomly assigning them to either an Atkins (very low carbohydrate), Zone (low carbohydrate), LEARN (high carbohydrate), or Ornish (very high in carbohydrate) diet. One study, published in JAMA in 2007, compared four weight-loss diets ranging from low to high carbohydrate intake. Researchers have begun comparing these “macronutrient management”-style diets to one another in order to determine which is most effective, but thus far evidence is largely inconclusive. With the proliferation of macronutrient-based diets over the past several decades, from low-fat to low-carbohydrate, discussion of the three main macronutrients – carbohydrates, proteins, and fats – has become standard when talking about optimal diets. View the HSPH news release, “Changes in specific dietary factors may have big impact on long-term weight gain: Weight-loss Strategy to Only ‘Eat Less, Exercise More” May be Overly Simplistic’” Managing macronutrients: Does it matter? Researchers did not discount the importance of calories, instead suggesting that choosing high-quality foods (and decreasing consumption of lower-quality foods) is an important factor in helping individuals consume fewer calories.Foods shown to be associated with weight loss were vegetables, whole grains, fruits, nuts, and yogurt.The researchers concluded that consumption of processed foods higher in starches, refined grains, fats, and sugars can increase weight gain. In a study of over 120,000 healthy women and men spanning 20 years, researchers determined that weight change was most strongly associated with the intake of potato chips, potatoes, sugar-sweetened beverages, and both processed and unprocessed red meats.Researchers in the Department of Nutrition at Harvard School of Public Health show us that quality is in fact very important in determining what we should eat to achieve and maintain a healthy weight, and that the notion of “a calorie is a calorie” does not tell the whole story. This type of research examining specific foods and drinks allows us to understand whether “a calorie is a calorie,” or if eating more higher-quality foods and fewer lower-quality foods can lead to weight loss and maintenance. One study analyzed whether certain foods were more or less likely to promote weight gain. There isn’t one “perfect” diet for everyone, owing to individual differences in genes and lifestyle. Lower-quality foods include highly processed snack foods, sugar-sweetened beverages, refined (white) grains, refined sugar, fried foods, foods high in saturated and trans fats, and high-glycemic foods such as potatoes.
High-quality foods include unrefined, minimally processed foods such as vegetables and fruits, whole grains, healthy fats and healthy sources of protein – the foods recommended in the Healthy Eating Plate.Rather than choosing foods based only on caloric value, think instead about choosing high-quality, healthy foods, and minimizing low-quality foods. Rather than focusing on calories alone, however, emerging research shows that quality is also key in determining what we should eat and what we should avoid in order to achieve and maintain a healthy weight. “A calorie is a calorie” is an oft-repeated dietary slogan, and not overeating is indeed an important health measure. Focus on eating high-quality foods in appropriately sized portions.The strongest evidence to date shows that calories matter, but focusing on food quality is an equally important part of preventing weight gain and promoting weight loss. Dietary guidelines have changed over the years as research becomes more accurate in determining what we should eat to attain optimal health and weight.