Q: I’m confused by the changing headlines: are low-fat diets the best way to lose weight?
A: Low-fat diets are one way to lose weight, however, cutting fat only works if it means you are eating fewer total calories. Fat is our most concentrated source of calories, so if you cut back on the amount of fat you eat – by adding less fat to food in cooking or at the table and choose leaner versions of some high-fat foods – you can cut calories and lose weight. Some processed foods advertised as reduced fat may cut fat but add extra sugar, and total calories remain the same. Or if you assume that you can eat a larger portion if the food is low fat, you can end up more than making up for calories saved in a lower-fat choice.
Studies that compare groups of people often do link lower fat diets with less likelihood of being overweight. However, analysis of studies that test effectiveness of diets low or high in fat show no difference in weight loss based on fat content alone. And in one study of nearly 90,000 European adults, neither the proportion of a diet’s calories coming from fat nor the type of fat made any significant difference in weight gain over four to ten years. Research does show that overall eating patterns high in fruits, vegetables and other plant foods are an excellent tool to lose and maintain weight. So make those foods the largest part of what you eat and choose small to moderate portions of foods high in healthful fats such as nuts or fish. It’s how all your food choices and portions come together that limits calories and helps you reach and maintain a healthy weight.