New diet study to raise eyebrows
There's a lot of bad information out there comparing diets, so I'm always eager to share any credible research I come across. I recently read a well-designed, two-year study coming out of Israel comparing three types of diets – and I think it's going to raise some eyebrows.
The study impressed me because of its thoroughness, the researchers monitoring weight, exercise, blood pressure and cholesterol levels. They also went so far as to give the participants regular sessions with dieticians to keep the participants on task — which is a country mile better than most examples of diet research. (What are you measuring when you're compiling stats from someone who has given up on a diet, or is in a binge pattern?) The Israeli researchers studied moderately obese people (as measured by body mass index), ages 40 to 65, including some who had type 2 diabetes or coronary heart disease. The focus of the study was a workplace, a medical center where a cafeteria lunch is the main meal (that's the custom in Israel). What people ate was well labeled nutritionally and individuals' diets were monitored by thorough electronic questionnaires. Each food item bore a label showing the number of calories and the number of grams of carbohydrates, fat, and saturated fat, according to an analysis from a nutritional database.
The subjects were separated into three groups on three diets: low fat, restricted calorie; Mediterranean, restricted calorie; and low-carb, restricted calorie. The Mediterranean diet prescribed a moderate amount of fat, the largest amount of fiber and a high proportion of monounsaturated to saturated fat — and the results showed cardiovascular benefits. The low-carb group consumed the largest amounts of fat, protein, and cholesterol. The low-fat, restricted-calorie diet was based on American Heart Association guidelines.
Two hundred seventy-two participants made it through two years of the study. The researchers were thorough. All groups had improvements in blood pressure and waist circumference, and all groups lost weight. The reductions were greater in the low-carb and Mediterranean-diet groups (an average of 4.7 kilograms and 4.4 kilograms, respectively, compared with 2.9 kg for the low-fat group).
The low-carb and Mediterranean groups also showed beneficial metabolic effects, which docs can get behind because it holds out hope for dietary strategies tailored to individuals and their individual metabolic needs. Impetus is given to these studies by a worldwide increase in obesity. The response in some places has been a rush to low-fat diets such as those promoted by the American Heart Association, but this study adds to the literature demonstrating limitations to that type of diet. The track record is spotty on people keeping the weight off after a period of restricting fat in the diet. The body needs fat -- too little can actually cause fatigue, emotional imbalance, and illness.
But you do need to eat the right kind. What's best are foods with natural fats from plants, fish, and other animals that haven't been injected with hormones and antibiotics. Avoid the man-made trans fats found in packaged baked goods and margarines—that's anything that says "hydrogenated" or "partially hydrogenated" on the label.
Low-fat diets generally do not work over the long-term because they don't supply your body with what it needs to run itself –and they make most people miserable. Yet they continue to be recommended, either by doctors who have little or no nutritional training or by dieticians who are locked into an outdated orthodoxy based on archaic, old science better left behind.
