Dietitians "Weigh the Evidence"

Both the scientific literature and popular press contain an astonishing amount of information about diet, nutrition, and weight loss. Joanne Hamilton, a registered dietitian (RD), says that her job is to "translate the science of nutrition and food into usable information for everyday people." Hamilton has been in clinical practice since 1988, and has extensive experience in helping clients achieve and maintain healthy weight. Diabetes is one of her areas of expertise, and she is the former chair of the diabetes educators section of the Canadian Diabetes Association. In addition to operating her own clinical practice, Hamilton works as a faculty developer at the University of Manitoba in Winnipeg, and teaches physicians how to give patients the tools and knowledge they need for successful weight management.

Hamilton is the author of "Weighing the Evidence on Weight Loss Approaches in Adults," an article published by the Canadian Diabetes Association in February 2008. The article provides an overview of the current scientific literature on weight loss and points out what works, what doesn't, and what remains unclear, and also makes recommendations about how RDs can best help their clients achieve their goals. Although the article is only three pages long, it cites 65 scientific papers and other references.

Be Rational and Persistent

The vast majority of people who lose weight through dieting regain it within a few years, and people often experience seven or eight failures before they achieve sustained weight loss. Hamilton stresses that people trying to achieve a healthy body weight should not give up due to setbacks; instead, these occurrences should be viewed problems to be solved, not insurmountable obstacles. People should adjust diets and exercise programs to their individual bodies, lifestyles, and needs, rather than continually moving from one diet to the next, because, "…to achieve and maintain a healthy body weight, people need to be rational and persistent." She emphasizes that there are no miracle diets: "Protein is not magic and carbs aren't evil. Research has consistently shown that the total number of calories is the most important factor in weight loss."

A diabetes patient is often cared for by a team of healthcare professionals, including a physician, an RD, an RN, and a counselor, all of whom play a role in helping the patient maintain a healthy diet and lifestyle. Hamilton says that people who do not have a chronic condition can gain similar benefits by assembling their own team of professionals. In Hamilton's 20 years of experience, people's eating habits haven't changed much. In general, we consume more calories and more meat than we need, do not consume enough dairy, and do not get enough daily servings of fruits and vegetables. (For recommendations for your age and sex, see Canada's Food Guide, the US Department of Agriculture's MyPyramid.gov, or the American Dietetic Association's Food & Nutrition Information page.)

Recommendations from "Weighing the Evidence on Weight Loss Approaches in Adults"

• To achieve and maintain long-term weight loss, people need to engage in more physical activities, eat a low-calorie, lower-fat diet, and maintain healthy behaviors. Controlling the total amount of calories consumed, rather than the proportion of carbohydrates or proteins, is the most important factor in a weight loss diet.

• Low-carb diets have been popular in recent years, but there is little scientific evidence to show that they promote effective long-term weight loss. Some studies report that diets emphasizing higher protein and lower carbohydrates promoted greater initial weight loss compared to other diets, but showed no significant difference after one year. In contrast, research from The National Weight Control Registry (NWCR) found that people who lost weight and maintained the loss were more likely to have followed a lower fat diet than a lower carbohydrate one.

• Eating habits that contributed to sustained weight loss include having breakfast and maintaining a consistent eating pattern across weekdays and weekends.

• Strategies and tools to promote satiety are required during weight loss. Ingesting non-caloric fluids, high-fiber foods, and foods with lower energy density can help promote satiety without exceeding the recommended number of calories.

• Self-monitoring is a crucial part of successful behavior change, and may include food and exercise diaries, weighing yourself daily, measuring changes in the percentage of body fat, and/or exercising with monitoring devices like pedometers and heart rate monitors.

• Personality traits that increase the likelihood of achieving a healthy body weight include strong motivation, an internal locus of control, and self-efficacy.

• Unhealthy eating habits are often motivated by emotional and psychological needs, and some people will benefit from stress management, psychotherapy, or other types of individualized counseling.

• Social and environmental support systems are important in establishing and maintaining a healthy lifestyle. Examples of social support include friends and family, peer support groups, online blogs and discussion groups, and internet diet and exercise tracking sites. When using internet resources, make sure that the information comes from a reliable and reputable source.

Hamilton's final message is that people should be highly critical when reading about diet and nutrition. One study does not automatically make something true. Just as it's important to obtain a second opinion for a disease diagnosis, it's important to find a second or third corroborating study before accepting new research findings as sound advice.

Dietitians "Weigh the Evidence"

Be Rational and Persistent

Recommendations from "Weighing the Evidence on Weight Loss Approaches in Adults"

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Sheng Wang

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