Diet is an important component of health promotion, but in comparison to other health behaviors it is relatively resistant to change. In my primary research area of medication adherence, the overall estimate is that half of all patients stop taking any given long-term medication within the first year. Similarly, half to three-quarters of people who start a new exercise regimen will drop it within the first 3 months. Treatment adherence in opioid use disorder (outside of clinical trials) is in the range of 10%-30%. But diet adherence is worse than all of these, with just 10% of patients maintaining a new diet for the first year. Only tobacco use, which is highly driven by physiological addiction, is a harder health behavior to change, and not by much. Why, then, is diet change such a heavy lift for many people?
If you have gained weight during the holiday season, you already know part of the answer to this question: Eating is a uniquely social behavior, and people are strongly influenced by social motivations. Food has strong emotional connotations -- your father carving the Thanksgiving turkey, your grandmother's Christmas fudge. It also has cultural meanings, with a meal serving as a shared experience that builds community with other people. I used to particularly look forward to the cup of hot spiced cider that our church had on hand after the late service on Christmas Eve. Many foods denote membership in a particular ethnic or cultural group: For Scandinavian Lutherans an example is lutefisk served at Christmas, or for German Lutherans fasnacht kuchle at the start of Lent. Many culturally beloved foods are not the most healthy examples of meals!
Besides social pressures, our diets are affected by food availability. Many people live in so-called "food deserts" with access to unhealthy food but limited access to fresh foods or ingredients for preparing their own meals. Ease of access clearly affects people's ability to eat a healthy diet. Cooking one's own food at home is almost always healthier than eating prepared foods, but it also requires time, adequate food storage and kitchen facilities, and expertise acquired through practice and instruction. All of those things are correlated with socioeconomic status, and therefore it's easier to eat a healthy diet if you also have other resources -- one aspect of the commonly observed association between health and wealth.
Diet is also a difficult behavior to change because it's relatively complex. Medication adherence, with a 50% success rate, is actually on the high end of modifiable health behaviors because it is so simple: For the most part, it just involves taking a pill on a certain schedule. (Sometimes there are complications like food/no food requirements, time-of-day rules, or different dosing forms -- all of those things tend to make adherence rates worse). Exercise involves starting a new behavior, which can vary in frequency and intensity, but it's still fundamentally about adding something new to your daily routine. Changing drug or alcohol use involves stopping something you are currently doing, which is generally harder than adding a new behavior and has correspondingly worse adherence rates. But diet change is the most complicated of all, because it involves changing a behavior that you already have. After all, you need to eat something! The modifications you make to your diet may be subtle or large, but the alternative of your previous diet is always there, and you might even intersperse old habits with new ones.
Finally, diet change requires a much higher level of knowledge or health literacy than many other forms of health behavior change. Foods have to be understood in terms of their nutrient content, not just their outward form. Furthermore, the same food (e.g., "cheese") can have very different nutrient contents even though it is known by the same name. Think of a milky Camembert, a sharp cheddar, a block of Manchego made from goat's milk, and a squirt can of cheez whiz. They are all nominally "cheese," but there are extreme differences between them and they can have vastly different effects on your health. Besides its content, food can vary in portion size, and making accurate judgments of amount requires considerable expertise. Prescribed diets usually specify a number of grams of a particular food, which may differ from the "portion size" on the package label, both of which may also differ from the actual amount that a typical eater consumes in one sitting. Have you tried counting out 8 tortilla chips to determine how many grams or calories of food you are eating? It gets old quickly.
To address these nuances, the U.S. Department of Agriculture in 2011 revised its old-school Food Pyramid to a new format called "MyPlate" that represents food groups based on the portion of a typical plate size that each food group should occupy. It's visually easier to follow, but the process is complicated by the fact that people don't eat just one meal per day, they can pile food higher or less high, they don't all use the same size plates, and they might not consume foods that separate easily into distinct groups (e.g., vegetables and chicken over pasta, with marinara sauce and parmesan cheese). Exact calorie recommendations depend on age, height, and gender, which argues for a personalized "MyPlate" eating plan but makes it harder to give generic public health recommendations about eating. And for some reason the MyPlate approach just hasn't seemed to catch on in the public consciousness -- people still talk about the Food Pyramid nearly two decades after it was officially retired. (There was an intermediate step, called MyPyramid, from 2005-2011. Hardly anyone remembers it now). The classic USDA food pyramid from 1992 was based on a Swedish version (originally from 1972) that had been used in schools for years before the Federal government officially adopted it. Despite controversy about specific proportions of different food groups, and the promulgation of specialized pyramids for various groups (children, adults with chronic diseases or food allergies, etc.), the classic food pyramid has the advantages of universality and ease of use, which may account for its continuing popularity.
The difficulty of even communicating diet recommendations clearly to everyone just underscores the overall point: Diet change is hard because diet choices are complex. Diet is therefore a health behavior that many people will need extra help to change.
Comments
Post a Comment