As health care costs rise and great attention is being paid to the health care system in many countries (perhaps especially the US), the debate is heating up over how to improve public health. Many health problems are greatly increased by the lifestyle choices individuals make – smoking, weight control, and exercise to name a few. The problem is that it is notoriously difficult to change behavior.
There are different ways to approach the challenge of improving lifestyle choices to reduce chronic illness. We can take actions aimed at the individual or aimed at society. These actions can be gentle or passive (the so-called “nudge theory”), or they can be more draconian, such as banning certain activity. We can, of course, do all of these things simultaneously, and may need to in order to have a significant impact.

Affecting Individual Behavior

A common criticism of mainstream physicians is that they do not have much impact on the lifestyle of their patients. This is largely true – although there is no convincing evidence that any practitioners have a significant impact on lifestyle. This is mainly the result of the fact that it is extremely difficult to get people to change their behavior.

The default tactic has been to give people information on the assumption that they will then be able to make a rational choice about their health. Psychologists have long known that we are much more likely to simply rationalize our behavior than take the more difficult path of changing it. This is true even of the “scared straight” approach – trying to frighten people with scary images or stories about lung cancer or diabetes.

It is true that physicians can affect patient behavior. For example, even brief physician counseling to quit smoking (less than 5 minutes) increases smoking cessation by 1.6 times. This sounds impressive, but this only increases the rate to 2-10%. Even if we use the higher number in that range, a 10% decrease in unhealthy behavior is very modest (worthwhile, but still modest). It seems that in general you can get about 5% of people to change their behavior with counseling alone.  Meanwhile, using medications to aid smoking cessation (nicotine patches and bupropion) can result in up to a 35% decrease in smoking.

The technology of changing individual behavior is advancing, however. The strategy of giving information and assuming rational behavior, while still useful, is highly limited and not sufficient. Psychologists recognize that the way to alter behavior is through psychosocial interventions – exploiting human psychology and peer pressure. One such technique is called motivational interviewing. Essentially, the patient is asked leading questions that get them to state their own health goals and concerns. Apparently we are better at persuading ourselves than being persuaded by others.

Sounds good, and generally the research shows that this approach is an improvement – but the effect size is still depressingly small. A systematic review of motivational interviewing for smoking cessation, for example, revealed only a 1.27 relative increase in cessation. So spending 5 minutes with a patient once improves smoking cessation by 1.6 times, and spending multiple 20 minutes sessions of motivational interviewing increases success a further 1.27 times. This is worthwhile in terms of public health outcomes, but it does look like such methods yield diminishing returns.

Motivational interviewing may be more effective for behaviors not related to addiction, such as weight loss and exercise. But still there is huge room for improvement.

Public Health Measures

It is increasingly looking like the way to have a huge impact on public health is at the societal, not individual, level. The goal is to make healthful lifestyle choices easier. Using heavy-handed legislation, however, is not popular (at least not in the US). Such strategies evoke images of a Big Brother nanny state trying to take away our freedoms. There are legitimate concerns about draconian state measures, especially if they are not rigorously science-based, but the looming health care crisis is making public health measures seem more attractive.

One approach is simply to ban unhealthy behavior. Outright bans of products, such as alcohol, have a disastrous history. Another alternative is to restrict the use of such products in certain locations and situations. The best example of this strategy is banning smoking in public locations. A systematic review of 10 studies indicates that such bans reduce the incidence of myocardial infarction in the population by an average of 17%. Banning smoking in public seems to be a clear public health win.

But banning unhealthy behavior gets more tricky when not dealing with addictive substances. Bans of fatty or high-calorie food, for example, are likely to meet much more resistance than restrictions on public smoking. New York City’s ban on trans fat, for example, has been highly controversial. Other states are considering laws to ban toys in kid’s meals, limit advertising, and limiting marketing behavior such as inviting fast food patrons to “go large.”

Resistance to heavy handed strategies has led to the proposal of the nudge theory – using more subtle legislation to influence behavior. Nudge strategies include printing the calories next to menu items. This is a situation in which information is likely to have a significant impact on behavior – because it addresses what may be a significant contributor to the increase in obesity. It is easy to consume far more calories than we think, especially when restaurants prepare menu items that are calorie dense in order to make them tasty and appealing. Having calorie information right in front of you when making menu choices does reduce caloric intake (in this study by 250 calories), although again, not as much as we might hope.

Another nudge approach is to make healthful choices the default choice. This still leaves consumers the freedom to choose what they want, but many more people will go with the healthier choice if it is the default.

Yet another approach is to regulate manufacturers. At present voluntary guidelines are being suggested, and the debate is ongoing about using legislation to require food manufacturers, for example, to produce healthier and lower calorie products. The public has been passively eating more calories simply because the products they buy contain more calories. They have also been lulled by false security – low fat products tend to make up their calories in carbohydrates, while low-carb products make up their calories with increased fat. Either way people eat more because they feel they are eating healthier products.


It is clear that we need to take a long science-based look at public health and ways to improve lifestyle choices. We need to reverse the obesity epidemic and further reduce smoking. Doing so is not easy – there is no silver bullet to changing human behavior. It is likely that we will need to use a combination of strategies while researching new and better ways to influence behavior.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the president and co-founder of the New England Skeptical Society, the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also contributes every Sunday to The Rogues Gallery, the official blog of the SGU.