If you are confused or frustrated by the conflicting claims about whether a low-fat or low-carbohydrate diet is the best, you are forgiven. First we were told that eating a low-fat diet was the best way to lose weight and improve heart health. Then, research suggested that low-carbohydrate diets were better. And back and forth it has gone for years.
During this time, the prevailing recommendations have suggested that a diet low in fat and high in carbohydrates was best. But more and more research has supported the notion that cutting carbohydrates, not fat, would lead to greater weight loss. Although this has been supported by some research, critics pointed out that eating more fat would raise blood cholesterol and other risks for heart disease.
According to a recent study, though, low-carbohydrate diets seem to have benefits for promoting weight loss and improving some indicators of heart health over low-fat diets. But you should hold off on shunning fruits and vegetables in favor of cheeseburgers! Here is a practical interpretation of the research and some common sense recommendations, taken from my Health & Fitness column in the Aiken Standard this week.
The study, published last week in the Annals of Internal Medicine, reported on 150 men and women who either restricted the amount of carbohydrates or fat they ate. After one year, the group that ate a low carbohydrate diet lost over 7 pounds more than the subjects on the low-fat diet. Additionally, the low-carbohydrate diet promoted greater improvements in blood lipids than the low-fat diet.
This is important for two reasons. First, this wasn’t a weight loss study; the researchers were simply following the subjects to see what would happen as they followed either diet. The fact that the low-carbohydrate group lost more weight suggests that it is relatively easier to cut calories following this type of diet.
This is consistent with other research showing that eating more carbohydrates, especially refined carbohydrates and sugar, can actually make people feel hungrier and eat more. Indeed, other studies have shown low-carbohydrate diets to be more effective for weight loss than low-fat diets (although a more recent study suggests there isn’t such a difference).
Second, the greater decrease in triglycerides and “bad” LDL cholesterol and increase in “good” HDL cholesterol in the low-carbohydrate group were different from what might be expected. Conventional wisdom holds that a low-fat diet should have a greater effect on blood lipids. Since weight loss can have a big effect on blood lipids, the improvement in the low-carbohydrate group may be due to losing more weight, not a direct effect of the diet.
It is important to note that the low-fat diet also led to weight loss in this and numerous other studies. The critical component of any weight loss diet is that it is relatively low in calories, regardless of what nutrients supply those calories. Really, almost any diet will lead to weight loss as long as it contains less energy than what is expended, but a low-carbohydrate diet may be more effective for weight loss than the traditional low-fat diet.
The bottom line is that the best diet is one that emphasizes eating wholesome foods, not on cutting carbohydrates or fat. That said, limiting carbohydrates in the form of refined grains and added sugar is an excellent way to reduce calorie intake and improve the overall nutritional value of what you eat. And shifting toward more monounsaturated fats (think olive oil and nuts) rather than worrying about the total amount of fat you eat is also a good idea.