Perspective
Christopher Gardner, Ph.D.
Credit: Steve Fisch
Christopher Gardner, Ph.D., is assistant professor of medicine (research) in the Department of Medicine, Stanford University. Dr. Gardner received his Ph.D. in nutrition science from the University of California at Berkeley and did his postdoctoral work at Stanford University. In early 2007, he published studies on four popular diets for weight loss and on garlic's effects on LDL cholesterol. (See summaries.)
How did you become interested in your particular area of research?
After receiving my Ph.D. in nutrition, I took a postdoctoral fellowship at the Stanford Prevention Research Center, which focuses on research to prevent chronic diseases through healthy lifestyle approaches. There, I received an opportunity from William L. Haskell, Ph.D., to direct a clinical trial investigating the effects of soy protein with or without soy isoflavones on serum cholesterol levels in postmenopausal women. With Dr. Haskell's mentoring and NCCAM funds, I conducted and published this small trial. Since then, my primary interest has been in trying to address controversial nutrition topics and health claims by designing appropriate clinical trials.
You've commented in a couple of interviews that some of the reporting on the four-diets study was, perhaps, not as balanced as you would have liked. Could you give us your view of the most important messages?
The gist of some of the more sensationalistic headlines and stories was that "the Atkins diet trounced all the other diets" or "eating all the bacon, eggs, and whipped cream you want is the best way to lose weight." This is not accurate.
What we found, in fact, was that the group assigned to the Atkins diet did modestly better overall at the end of 12 months than the groups assigned to the Zone diet, the Ornish diet, or the LEARN diet. All four groups lost weight, on average, and all four experienced improvements in related metabolic risk factors (e.g., cholesterol, blood pressure, insulin). There were statistically significant differences among the diet groups at the end of 12 months, and in each case the differences favored the Atkins group over one or more of the other groups. However, the differences tended to be modest.
We were also studying how well real people followed these diets as prescribed, on their own, over an extended period of time. The answer was, not very well.
But the most important message, we believe, is that the findings reinforce the need to cut back on or eliminate refined carbohydrates from our diets when trying to lose weight and keep it off. The most common sources of refined carbohydrates are sweetened caloric drinks, white bread, cookies, candy, and products with high-fructose corn syrup added. Many people think of Atkins as "all the steak and butter you can eat," but its primary focus is cutting out refined carbohydrates and choosing nutrient-dense vegetables as your primary source of carbohydrates.
What are the most important things a person should consider about a dietary approach to losing weight or keeping it off?
For both purposes, the most important thing to do is choose a diet you can follow for the rest of your life, not just for a month or two. If you find a way to lose weight right now, right away, but you cannot maintain the same type of diet long-term, then when you stop the diet and return to old eating patterns, the weight is likely to return. Extreme very low-fat, very low-carbohydrate, or very high-protein diets are all difficult for most people to maintain long-term. Also, such approaches may not be best for long-term health--for example, if you develop deficiencies in vitamins and minerals; if taking in more protein than you need over a long period leads to impaired kidney function and a deficiency in calcium; or if an approach that is low in fiber and high in saturated fat raises several risks related to heart disease and cancer.
What are some areas that you find compelling for future research?
We still do not fully understand how to best create the feeling of fullness from a meal that gives us the cue to stop eating (satiation). Nor do we understand enough about the best strategies for maintaining that feeling of fullness for the longest time and delaying the sense of hunger from returning (satiety). The key to all this likely involves some combination of portion sizes; energy density; manipulations of carbohydrate, fat, and protein; and hormones like leptin and ghrelin that the body produces. We also need to develop better tools for assessing outcomes in these studies.
