When the US Congress starts holding hearings to regulate an industry, you know that something is wrong. It’s little wonder that the diet industry came under review over the past few years. Despite the rapidly increasing incidence of obesity in the United States, dieting and diet related products exceeds $4 billion dollars in gross sales annually. Obviously something was wrong. Millions of people were spending billions of dollars and the problem was getting worse.

In recognition of potential problems in the diet industry, and the great potential to create scams, several guidelines were set by the federal government to establish standards for weight control programs. One of the recommended standards was the publication of the success rates for any program or treatment. Given that one of the most quoted research articles on the subject found only a 5% long-term success rate, it is little wonder that programs did not rush to publish their success rates. In fact, to this date, I have not seen any published figures from any of the major diet centers including Weight Watchers or Jenny Craig on success rates.

There may be many reasons, only one of which may be to fool the public and make more money. Success rate is a difficult problem to measure in weight control. At first glance, you would think it straight-forward and simple; report how much weight has been lost during the program and how much has been kept off one or more years later. Not as easy as it seems. For one, how do you report the drop-outs? One program I know reports 100% success rate because they throw people out of the program if they fail to lose weight. They only keep the successes and don’t even consider the damage done to those who have been terminated. Another is finding the people years after treatment and confirming their weights. If you do it by phone, there is no way to confirm or deny the outcome. If you ask people to come in, the number that are willing can be quite small.

In addition to logistics, the bigger problem is the criteria to measure success. If it is simply weight loss maintained, what do you do with the person who is already too thin and should be gaining rather than losing? Is it successful if the person is eating healthy and in moderation, exercising at least 3 times per week but has not lost any weight and whose weight may be the same one year later? What do you do with the natural pattern of weight gain over the lifespan? If you gain only 5 pounds when the average is 8 pounds, have you failed to maintain your weight loss during that time?

It is not simple nor is it easy. With the burn rate approach, success cannot simply be measured by pounds lost and maintained. Success rate has to account for people whose burn rate is already low, should not lose any more weight, and may even gain weight as they naturally age. It has to account for the person who can lose a small amount of weight and keep it off as well as the person who has the capacity to lose a large amount of weight. Most importantly, it has to account for the changes in the person’s psychology of weight control – the reduction in tension, guilt and shame that should accompany any successful approach.

The only measure of success rate that can include all those categories is the changes in a person’s health behaviors. In order to succeed, the person needs to have their daily calorie intake be within the normal or recommended range. The measure of health is whether their intake is consistent with their burn rate and within the normal range Another measure is the consistency of their exercise program. How many weeks per month does the person burn greater than 800 calories per week in exercise? The last measure needs to address the psychological issues of guilt and shame. Does the person continue to blame himself or herself for the problem, or do they understand it from a burn rate perspective? Are they too hard on themselves? Is there enough flexibility in their food intake, or are they overcontrolling?

These measures are difficult to define, let alone capture. Many patients come to see me, undergo the burn rate evaluation, and I never see them again. I can only hope that they are successful and can’t prove it. Other patients see me for weeks and months and I can track their health behaviors. These patients are in treatment and their weight fluctuations can result from treatment or be caused by treatment. Evaluating outcome would have to wait until treatment stopped. To make matters even more confusing, I see some patients life-long with periodic check-ups to maintain their weight. Are these patients still in treatment and how should they be included?

Measuring success is not as simple as measuring weight loss and gain. The only reasonable measure is health behaviors for all patients in treatment, including drop-outs, that include psychological measures: food intake relative to burn rate, exercise patterns., and changes in guilt, and shame. So next time you ask a health professional “What is your success rate?”, be prepared for a long winded response.