Obesity weight-loss assumptions in perspective

In a study published on Jan. 31 in the New England Journal of Medicine, researchers investigate the myths, facts and assumptions associated with losing weight in obese patients (N Engl J Med. 2013;368:446-454). This study has deservedly received a substantial amount of attention, both in the medical news and the layman’s press, such as The New York Times.

The authors brought up really good points, but — and this is the keyword: but — are their conclusions obfuscated or confusing?

Let’s address some of the specific points in the study and the perspective from which they are made. Following are some of the assumptions that they examine.

Adding fruits and vegetables to the diet results in weight loss

The authors highlight that this statement is inconclusive. That while fruits and vegetables may be good for your health, they don’t help with weight loss.

But you have to analyze this statement more closely. They are not saying that fruits and vegetables don’t help with weight loss. They say that adding them is not helpful. I agree that if you add these items to a diet of cheeseburgers and fries, you are certainly not going to lose weight.

However, if you shift your diet to one that involves a vegetable-rich, plant-based approach, this has a much different effect than just adding fruits and vegetables without making any other changes. There are a number of studies showing significant long-term weight loss with this type of diet. For instance, in a small, retrospective study, patients on a plant-based, nutrient-dense diet involving a significant amount of fruits and vegetables, lost an average of 33 pounds in the first year and 59 pounds in the second year (Altern Ther Health Med. 2008;14:48-53). Granted, this is not the best-designed study, but it suggests that vegetable-rich diets are effective for significant and sustained weight loss.

Slow, gradual weight loss is best for long-term success

The authors debunk this as a myth. However, what do they mean by this statement? Using a meta-analysis, the results show that ultra-low calorie diets are more effective for losing weight than a slow, gradual approach (Int J Behav Med. 2010;17:161-167). This all seems to make sense.

But, the authors compare weight loss of 16 percent to 10 percent over six months. While this may be statistically significant, it is not necessarily clinically rapid versus slow weight loss. For instance, a 200-pound obese patient who loses 16 percent of her weight has lost only 12 pounds more than someone who loses 10 percent of her weight in six months. This is roughly two extra pounds a month.

A diet primarily focused on severe calorie restriction, rather than nutrient density, may work for the short term, but it may throw the homeostasis of the body’s hunger-inducing hormones, such as ghrelin and leptin, into disarray. This creates an environment that may actually cause weight to be regained in the long term (N Engl J Med. 2011; 365:1597-1604).

Another thing to consider is that a low-calorie diet may not necessarily increase life span, as we once thought. This was demonstrated in a study using rhesus monkeys (Nature online Aug. 29). In my Sept. 13, 2012 article, entitled “Calorie restriction disappoints in longevity and quality of life,” I addressed that fact that there may be better ways to lose weight than calorie restriction. One option is the DASH diet, which reduces the risk of heart disease and other chronic diseases (Arch Intern Med. 2008;168:713-720).

Bariatric surgery is valuable for some patients for long-term weight loss

The authors conclude that this may be true, and they support their statement with a prospective trial (N Engl J Med. 2004;351:2683-2693). I agree that it may be appropriate for some patients.

But, what is not mentioned is that at least 50 percent of patients who have bariatric surgery tend to regain weight within 24 months, so that the original BMI change is no longer significant (Obes Surg. 2008 Jun;18(6):648-651). There are also significant side effects for some patients who undergo bariatric surgery, such as the dumping syndrome, which can occur especially with high levels of simple carbohydrates in as many as 50 percent of patients, and the inability to properly absorb nutrients, such as B12, calcium, iron and folate (Surgery. 1960;48:185-194; Obes Surg. 2005;15(2):145-154).

Weight-loss pills and prepackaged meals may be effective tools

According to the author, weight-loss pills and packaged meals may be the best options for weight loss.

But, the history of weight-loss pills is tarnished. So many of them have been pulled off the market after being approved, because of untoward side effects. Also, once patients discontinue the drugs, they appear to regain the lost weight.

I don’t disagree that diets providing packaged meals are effective ways to lose weight.

But, just like with drug therapy, once patients discontinue the meals, they tend to regain weight. Just like the old saying, it is better to teach a man to fish than to provide the fish for him.

Is this study potentially biased?

There may be some bias involved as well, since the authors are not without conflicts of interest. Most of them are associated with pharmaceutical companies as paid speakers, or they consult as well as associate with food manufacturers and prepackaged meal providers. It is true that disclosing this information is important, but take note when reading any study of the authors’ affiliations — they tend to color their perspectives.

Benefit of small energy changes

Small, sustained changes in energy-intake or expenditure will produce large, long-term weight changes.

The authors conclude that this is a myth. I emphatically disagree. In fact, last week I wrote about the positive effects of exercise on weight loss. Those that lost the most weight and sustained that loss not only did moderate activities, about 30 minutes a day, four to five times per week, but also were less sedentary the rest of day, as demonstrated by a pedometer (Am J Prev Med. 2012;43(6):629-635).

The authors do bring to light some very pertinent points. They address some other assumptions that really are not based on any scientific evidence. I would encourage people to read the article in its entirety.

But know that not all of the points have been flushed out completely, and keep in mind that the authors have their distinct perspectives and quite a few conflicts of interest.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.