Imagine for a second that you have steadfastly ignored all of the conflicting messages in the news, commercials, and the internet about weight loss diets over the last 10 years. Instead, you studiously read only clinical research in scholarly journal articles. You would be extremely enlightened and well educated about the “best” diet for weight loss, right? Wrong. It turns out that for every study that supports a certain approach for weight loss there is another that supports the opposite. This conflict has caused scientists and clinicians to debate about “best” diet; each citing as evidence a long list of studies that his or hers as the “holy grail” of diets.

Researchers at Harvard School of Public Health and Pennington Research Lab at Louisiana State University teamed up to set the record straight. The team recruited 800 overweight volunteers. They randomly assigned each volunteer one of four diets: low-fat/high protein, low-fat/moderate-protein, high-fat/average protein or high fat/high-protein. If a diet was high in protein, it was lower in carbohydrates and if the diet was lower in protein it was higher in carbohydrates. In order to cause weight loss, each diet was designed to have the participant eat 750 less calories per day than they needed to maintain their current weight  Each subject was asked to strictly adhere to the diet for 2 years.

Which diet did they find worked the best? Whichever diet resulted in the person eating less calories for the longest period of time. In contrast to what the fad diet marketers will tell you, the person’s satisfaction with the diet and their hunger levels was the same regardless of the type of diet. The authors concluded that: “… diets that are successful in causing weight loss can emphasize a range of fat, protein, and carbohydrate composition”. In other words, diet success is not a dependent on the content of the diet but on the calories consumed.

How did this study show no difference between diets while other studies have shown a strong preference for one or the other?  Unlike most other weight loss studies, this study made a concerted effort to include volunteers from all different walks of life (older, younger, men, women, rich, poor etc.). Importantly, the study also recruited a fairly large number of people. This large number of subjects, known as sample size, gives the researchers the ability to better trust their results. Also, the volunteers in this study were followed for 2 years while most others follow volunteers for 1 year or less. As you may know first hand, diets become increasingly hard to stick to after 6 months. By following people for 2 years, the researchers were able to get a handle on the long-term effect of each diet. Essentially, this study was designed to avoid  the flaws and pitfalls in most other weight loss studies that resulted in so many conflicting results.

Although the results from this study are important by showing that reduced calories are the most important factor of weight loss success, it is not the first to find this to be the case. A landmark study done by researchers at Tufts University essentially found the same thing. They compared 4 of the most popular weight loss diets in the United States: Atkins, The Zone, Weight Watchers, and Ornish. Like this study, each volunteer was randomly assigned one of the four diets. After 1 year, the researchers found that the most important factor for success was not high carb or low fat, but how well the individual stuck to each diet.

The practical message from this research is that the “best” diet out there is whichever helps you eat less. The next time that you are evaluating a new diet, the question shouldn’t be: “What it is?” but instead: “How Much”?.

Links to Full Text Articles:

NEJM Article

Popular Diet Article

About the Author:

Brian Dean MS, RD is a registered dietitian and researcher. After years of research, Brian has set his sights on helping those with lower back pain.  He serves on the Medical Nutrition Committee for The American Society for Nutrition and is a professional member of numerous research organizations including the International Association for The Study of Pain, American Chronic Pain Society, and The American Dietetic Association. He recently created a research-based lower back pain treatment program called The Back Pain Diet which is available from his website Stop Lower Back Pain

A nose that weighs about 4 or 5 pounds, that is.

A recent Stanford University study compared the benefits of four different weight loss programs: Atkins, Zone, Ornish and Learn diets. What they found was that after 12 months the average weight loss with the Atkins diet in overweight and obese but otherwise healthy women was about 10 lbs. which was more than with any of the other diets. The next best diet was the Learn diet with an average weight loss of about 5.5 lbs. The Ornish and Zone diets produced about a 3 or 4 pound weight loss after one year.

Of particular interest was that the amounts of fats in the blood (triglycerides in this case) were lower in the Atkins group by the end of the study than in the other diet groups. Since the Atkins diet is a high fat diet and very low carbohydrate, while the others are low in fat and relatively higher in carbohydrate, the finding of better triglyceride levels with Atkins was unexpected.

I applaud the hard work and effort made by these researchers to uncover these findings. Unfortunately I don’t think they have provided us with enough information to make an informed decision about whether the Atkins diet is truly the best of these four dietary approaches to weight loss. It has been my experience that many who start the Atkins diet fail to adhere to it for very long. Many people tell me they find that the high fat of content of Atkins makes them want to vomit. Making matters worse the development of ketones in the body that are thought to be crucial for success of the Atkins diet also induce nausea. Perhaps it is the effect of a high fat diet to make you sick to your stomach that causes some of the weight loss. In the Stanford University experiment each participant was carefully selected and nurtured through the study. Even with this level of care, of all the subjects starting a diet about 1 in 5 couldn’t finish a year. Without the intense personal support from study coordinators that goes with this type of clinical research I predict many fewer people would last a year on the Atkins. In the real world my concern is more for those who couldn’t finish the diet than for those who did. What if a person consumes all those fat calories and can’t lose weight? What happens to their blood fat levels, blood pressure, body mass etc?

A researcher reading these comments may go “Piss-posh…who ever studies the drop-outs from a study? These people simply disappear.” I assume the drop-outs themselves and their doctors are concerned about the drop-outs. If someone is placed on a diet by their doctor and doesn’t succeed on it, the patient and the doctor still have to deal with the aftermath. It would not surprise me at all if a lot of bad things happen in the body of those non-losers on Atkins.

So I say, let’s attend to the drop-outs and non-losers as well as those who succeed with their diet. Let’s study high fat diets in a real world environment without a million dollar budget for support staff and other luxuries. I need to tell my patient what happens if they are unsuccessful on Atkins as well as if they succeed. Will their triglyceride, blood pressure, and sense of well-being deteriorate? If that is the risk they must take for losing 5 pounds more then with the Ornish, Zone, or Learn diet I would think twice about suggesting the Atkins diet. When the “non-loser study” is available I’ll feel much better informed about which diet to recommend then I do now.

Only you and your own doctor can decide what is the best treatment for you. The comments made here by the staff at metabolism.com are purely for educational purposes and are not meant to guide you in the treatment of any condition or illness.

Gary Pepper, M.D. FACP
Editor-in- Chief, Metabolism.com