Fat: the old public health enemy #1
For years we have been told that fat is the problem and sugar is good for us, or so it seems. Now we are hearing that fat is not the enemy after all. It’s the carbs! Why were we so deliberately deceived? First, I do not blame nutritionists or dietitians for making fat the bad guy. Second, I do not believe that carbs are as bad as they are currently being made out to be or that fat was as bad as its previous reputation. Finally, it seems that all the overreaction to too much fat in our diet, spread by self-appointed food pundits, is now being repeated with respect to carbs. Don’t be surprised if sometime down the road we hear that carbs are not so bad for us and that we have a new public health enemy #1.
Why did we hear that fat was so bad for us in the first place? In my courses on human nutrition, I learned that the main problem with fat in food is that it has twice the amount of calories per ounce as carbs and proteins. In practical terms it means that a diet high in fat is twice as likely to make us fat as a diet low in fat. Too much fat is also associated with elevated blood cholesterol which has been implicated in heart disease. Some studies suggested that foods high in cholesterol like shrimp and eggs can also contribute to high levels of blood cholesterol. A key study conducted at Harvard and published in 1999 in the Journal of the American Medical Association1 found that foods high in cholesterol are not as great a factor in blood cholesterol as previously believed. That conclusion has been confirmed by numerous other ones leading to lifting strict restrictions on eggs and other foods high in cholesterol. The most recent US Dietary Guidelines say that we can eat more eggs in our diets than recommended in the past but caution us not to overdo it. The main message in the guidelines, however, is to make sure that we are not consuming too many calories. Many food pundits who blamed fat for so many years have now shifted their fire to carbs, particularly sugar.
Carbs: the new public health enemy #1
Isn’t it clear that the main reason American get fat is that they eat carbs? It is clear that Americans eat too much sugar. The problem with sugar is that the only nutritional benefit of added sugar is that it provides energy in the form of calories. Calories in and of themselves are not bad, as we all need calories to live and do what needs to be done in our lives. Again, it is too many calories that is leading to the fattening of America. The biggest problem with processed, restaurant and homemade foods that are high in sugar and fat is that they contain too many calories relative to the amount of vitamins and minerals they provide. A review article published this year in Progress in Cardiovascular Diseases2 indicates that replacing saturated fats in processed foods with added sugars increases the risk of heart disease. It does not condemn carbs as a class of nutrients in foods and cautions us not to overgeneralize on the effects of sugars and saturated fats.
Some processed products like whole chocolate milk, for example, contain both high levels of vitamins and minerals as well as too much sugar and fat. A parent of a child who will not drink white milk even under threat banishment to their room or other form of punishment must decide if the beneficial nutrients in chocolate milk compensate for the excess calories. Sugar also contributes to levels of blood glucose which are necessary for proper brain function. Glucose can be obtained from complex carbs such as starches. Nutritionists and dietitians recommend that we try to get these complex carbs from vegetables and whole grains. For the first time the US Dietary Guidelines propose a restriction on the number of calories from sugar but not from carbs as such. Food pundits are not as nuanced in their recommendations.
Why then do we need to have a bad guy? It appears that it is difficult to tell Americans what to do without separating the world into good guys and bad guys. I grew up watching Westerns such as Roy Rogers and The Lone Ranger where the good guys wore white hats and the bad guys wore black ones. Even better, the good guys always won in the end. When I grew up and went to college, I was taught in my liberal-arts classes that the world is not that easy to describe and that we live in a world of shades of gray. Nutritionists and dietitians provide guidelines that steer us away from dividing foods into good ones and bad ones. They emphasize that a healthy diet is a balanced diet providing sufficient vitamins and minerals without too many calories, and they proclaim that a calorie is a calorie. Food pundits who preach to us in terms of foods that we should eat and those we should avoid are much more definitive in their approach suggesting that some calories more equal than others. I am not afraid to eat processed food within the guidelines provided by nutritionists and dietitians. Are you?
Next week: The Food Lab and the science of cooking
Postscript: Today I pick up my first Veggie Box in town containing fresh, locally grown, organic vegetables. I have subscribed to this service for the next five months. I will be reporting on my experiences in future posts. Stay tuned.
1 Hu, F.B., M.J. Stampfer, E.B. Rimm, J.E. Manson, A. Ascherio, G.A. Colditz, B.A. Rosner, D. Spiegelman, F.E. Speizer, F.R. Sacks, C.H. Hennekens, and W.C. Willett, 1999, A prospective study of egg consumption and risk of cardiovascular disease in men and women, Journal of the American Medical Association 281:1387-1394
2 DiNicolantonio J.J., S.C. Lucan and J.H. O’Keefe, 2016, The evidence for saturated fat and for sugar related to coronary heart disease, Progress in Cardiovascular Diseases. 58(5):464-472 DOI: 10.1016/j.pcad.2015.11.006.