Fat still matters

Last week I wrote about some recent research suggesting that low-carbohydrate diets may be better for weight loss that low-fat diets. For many, this study reinforced the notion that traditional recommendations are wrong and that the key to good health is to eliminate carbohydrates from your diet. This couldn’t be further from the truth.

The recent study did show that people lost more weight and experienced beneficial changes in blood lipids when they followed a low-carbohydrate diet compared to those who ate a low-fat diet. However, this does not mean that low-fat diets aren’t effective for weight loss or that they are “unhealthy.”

In fact, low-fat diets have long been used effectively to promote weight loss, reduce heart disease risk, and lead to healthier eating in general. This is supported by the results of hundreds of research studies as well as the practical experience of health professionals and real people. Here are two reasons why fat still matters when it comes to health.

First, reduced-fat diets have been shown to improve blood cholesterol and lower the risk for heart disease. Eating a diet low in fat, especially saturated and trans fat, has been the foundation of nutrition recommendations for decades. The fact is that these diets are effective for weight loss, reducing cholesterol, and otherwise improving heart health.

One famous study demonstrated that following a low-fat diet contributed to a reduction in the severity of atherosclerosis, the narrowing of arteries that leads to many heart attacks. Literally hundreds of other studies have shown similar beneficial results.

This isn’t some magical effect of eating less fat, though. The health benefits are likely due to eating more vegetables, fruits, and whole grains as much as they are to reducing fat intake. The point is that adopting a low-fat diet can lead to better nutrition overall.

Second, reducing fat intake is a good way to reduce calories. This is true because fat contains nine calories per gram, more than twice that of carbohydrates and protein, so cutting fat is an effective way to cut calories. Limiting fat intake also reduces calories indirectly because many high fat foods are also high in sugar and calories (think of most desserts).

It is important to mention that simply reducing fat intake won’t always lead to weight loss; total calories must be lower, too. This is a mistake many make when they reduce fat intake, but increase the amount of calories from other sources, typically carbohydrates. Many low-fat foods are actually relatively high in calories due to added sugar or people tend to eat more of them (the SnackWell Effect).

The effectiveness of low-fat diets for weight loss has been demonstrated in research studies (like this one) and countless weight loss programs. In one notable study, a diet low in fat even led to weight loss in people who weren’t trying to lose weight. And don’t forget that in the recent study about low-carbohydrate diets, the subjects that followed the low-fat diet also lost weight.

For some people, cutting carbohydrates as a way to lose weight is reasonable; for others, reducing fat intake makes sense. For most people, though, doing both to some extent is the best option, but going to extremes is unnecessary.

Eating less added sugar and avoiding foods with added fats (such as French fries) are good recommendations for almost everyone. That said, there is little evidence for the benefit of limiting carbohydrates in the form of whole grains, legumes, vegetables, and fruits or the fat in meat and dairy.

The bottom line is that the quality of food we eat is more important than the specific amounts of the nutrients it contains. Eating low-carbohydrate or low-fat diets can help steer you toward making healthier choices, but so can avoiding processed foods in favor of wholesome, nutrient-dense “real” food.

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