Its time to differentiate between good and bad diets rather than simply good or bad foods. 
In the 1970's and 80's nutrition experts began advising Americans to cut their consumption of saturated fat and cholesterol to reduce their risk of heart disease. By 1990, official dietary advice was to keep total fat to no more than 30 percent of calories. Subsequently, the American public was subjected to a barrage of nutrition advice designed to help lower the national propensity towards obesity and associated ailments. One message that came across loud and clear was that "fat is bad."
The public heard this message, and so did the food industry. And the food industry provided a wide array of no fat, low-fat, reduced-fat, light and 'lite' products to allow Americans to eat their cake but eat no fat. In some ways, the message worked.
According to government figures, Americans reduced the percentage of calories from fat that they ate from around 37 percent in 1960, to around 34 percent by 1984. But, the total fat consumption per person increased, as did the average calorie intake. According to Department of Agriculture data, in 1977-78, the average daily calorie intake was 1,850 calories; by 1994-96, this figure had increased to about 2,000 calories.
The result of such an increase? Well, in 1977-78, 18 percent of women over 20 years old were overweight, as were 22 percent of men. In 1994-96, these percentages had increased to 32 percent for both men and women. Thus, the emphasis on dietary fat reduction did not stem the rising tide of obesity, and the percentage of overweight and obese Americans continues to increase.
Was the message wrong? Is it okay to eat a high fat diet? Perhaps, we are now being told, the real culprit is sugar not just any sugar, but added sugar. The implication is that if we shun foods with added sugars, we will somehow be able to make a dent in the increasing proportion of obese Americans. But this is not necessarily true, and is not really the message we want to send.
This seesawing between nutrients as culprits highlights a significant problem with addressing nutritional issues in the United States. We tend to oversimplify in order to (we hope) get our message across. Americans want a magic bullet to good health and simplifying nutritional issues to "bad-good" suggests that there is one. But the real message seems to be getting lost, and reliance on a "bad-good" dichotomy helped get us into the low-fat dead end.
What nutrition professionals want people to understand is how to choose a diet that is appropriate in terms of calorie content, as well as in content of essential nutrients. That's why the government (the Department of Agriculture and the Department of Health and Human Services) devised the Food Guide Pyramid and the Dietary Guidelines for Americans. These educational instruments provide a roadmap that allows Americans to see which foods should make up the bulk of their diets, and in what proportions.
Further, not only do they suggest which foods to eat, and in which proportions, they also indicate appropriate portion sizes a concept that is foreign to many of us, but is crucial to understand if one is to control body weight.
It would be more productive to focus on positive messages to teach consumers about appropriate food choices, rather than emphasizing negative ones although the latter make better headlines. By telling people that fat is "bad," and that the way to lose weight is to eat low-fat foods, we diverted attention from the real issue: too many calories in and too few out in physical activity. Should we repeat this error by telling consumers that it's really the added sugar that's "bad"?
Labeling foods or ingredients as '"good" or "bad" is simply an unhealthy red herring it is quite possible to avoid added sugars and still have a poor diet!