Low-Fat Diets are Ineffective Long Term

I find it interesting and really sad how certain dietary myths become so well accepted by the population that they remain a dietary “fact” no matter how much the science says otherwise. Such is the case with dietary fat. Walk around your grocery store and you’ll still see low- and reduced-fat everything (milk, yogurt, mayonnaise, etc.) as if it were the most poisonous ingredient in the store.

I’ve discussed many times how I’m not a big fan of restrictive diets that emphasize the elimination of major macronutrients like carbohydrates or fats.

Low-fat diets, in particular, are proving to be one of the most ineffective ways of eating, especially with regard to their effects on weight loss and disease prevention. In fact, the results now indicate that as fat was removed from the diet over the past 50 years, obesity actually increased proportionately.

Low fat diets minimize the consumption of fats—a major macronutrient—to below 35% of your daily calories. Some plans allow only 15% of your calories to come from fat sources. Most low-fat diets emphasize lots of lean proteins (such as turkey, and chicken breast), and low-fat or fat-free dairy. Full-fat dairy, egg yolks, and fatty cuts of meat (including most red meat) are avoided.

A lot of early science (in the 1950s and 1960s) pointed to heart benefits as a result of decreased fat (particularly saturated fat) intake. And this is how the myth arose. But this hypothesis was further tested and the more science learned about fat in recent years, the more it has become clear that fat was vilified based on a number of assumptions that just weren’t true. And in fact, it has now been demonstrated that as modern humans eat lower fat diets, we actually eat more, and specifically we eat more carbohydrates. This, in turn, causes obesity. We now know that fats that come from the right natural sources aren’t bad for you and have an important place in your diet.

As for weight loss, you can shed pounds in the short term by cutting out dietary fat, but as indicated earlier, research shows that long-term success is a different story.

In a meta-analysis published in 2002 that looked into low-fat diets and weight loss, researchers wrote, “in trials lasting one year or longer, fat consumption within the range of 18-40% of energy has consistently had little, if any, effect on body fatness… Diets high in fat do not account for the high prevalence of excess body fat in Western countries; reductions in the percentage of energy from fat will have no important benefits and could further exacerbate this problem. The emphasis on total fat reduction has been a serious distraction in efforts to control obesity and improve health in general.”¹

Those are strong words for sure…but more and more research is supporting this idea.

In fact, a much more recent huge meta-analysis published in December 2015 has provided even more validation that low fat is not the way to go if you want long-term weight loss success. In it, researchers aimed to determine whether low-fat diets contribute to greater weight loss than participants’ usual diets, low-carb diets, or other higher-fat plans.

They examined the results of 53 studies (for a total of 68,128 individuals). They found that low-carbohydrate diets led to significantly greater weight loss than low-fat plans. Additionally, low-fat plans “did not lead to differences in weight change compared with other higher-fat weight loss interventions.”

The researchers concluded, “[W]hen compared with dietary interventions of similar intensity, evidence…does not support low-fat diets over other dietary interventions for long-term weight loss.”

Choose a Lifestyle, Not a Diet

While low-fat diets have decreased in popularity as of late, many doctors and medical associations still recommend them, mainly for heart health. But I think we can safely say at this point that if your goal is to lose weight and keep it off, low fat is not the best way to go.

The only fat you really need to eliminate is trans fat, a manmade disaster that can lead to a multitude of health problems. Additionally, much of the research (including studies from my own lab) reveal that you should also limit your intake of pro-inflammatory omega-6 fatty acids, which primarily come from cooking oils such as soybean, corn, and vegetable oils. Otherwise, dietary fats, including some saturated fat—and especially heart-friendly omega-3s—can and should be a healthy part of your diet.

As I always emphasize, the key to weight loss success is a sustainable diet that includes plenty of life-enhancing macro- and micronutrients—and that includes fats and complex carbohydrates. Doing so allows you to control your calories and lose one to two pounds a week—a rate that is realistic and sustainable.

I strongly believe that when you choose to make positive changes to your diet—as perhaps you have resolved to do in 2016—you should pick an eating plan that you can adopt permanently. Diets that are easy to follow and not the least bit restrictive include the Mediterranean diet and the Gene Smart diet. Not only do they tend to appeal to the masses, they benefit nearly everyone’s health and waistlines.