November 6, 2020

HOST: Many Americans go on special diets for different reasons. Weight loss simply for appearance sake is obviously a major reason why some people go on special diets. But there are several other, health-related reasons why almost 1 in 5 American adults go on these special diets.  In order to help people achieve and maintain a healthy body weight, support nutrient adequacy, and reduce the risk of chronic disease, the 2015–2020 Dietary Guidelines for Americans recommend following a healthy eating pattern across a person’s lifespan.

Joining us today is Bryan Stierman, an epidemic intelligence officer with the CDC’s National Center for Health Statistics. Dr. Stierman works with the NCHS National Health and Nutrition Examination Survey, or NHANES, and he is the lead author on a new study on Special Diets among American adults.

Dr. Stierman could you tell us a little bit about the background on this study why you undertook this research on special diets?

BRYAN STIERMAN: Sure absolutely. So it’s useful to understand what exactly were studying, so I’ll start off just kind of by generally discussing what an eating pattern is. So an eating pattern is the combination of foods and beverages that a person consumes over time. So with this in mind we were interested in looking at special diets which are actually specific eating patterns that somebody uses for weight loss or other health related reasons. For example, other health related reasons could well include medical conditions such as diabetes or kidney disease. A little bit of background on NHANES or the National Health and Nutrition Examination Survey could also be useful. So NHANES is a nationwide survey created to assess the health and nutrition of adults and children in the United States and the survey combines interviews with physical exams and laboratory testing. So the basis of our report, our questions that the NHANES survey asked about special diet use that were specifically asked during a dietary interview .

HOST: And so how many people participated in the study?

BRYAN STIERMAN: So the bulk of our report focuses on the years 2015 to 2018, which is the latest data that’s available from the NHANES survey and was released this past June. And in this four year period nearly 10,000 adults over the age of 20 participated in NHANES and answered these questions related to special diets. So we looked at participants from these four years as well as from earlier years in order to be able to see how things changed over time.

HOST: And how many adults are on a special diet?

BRYAN STIERMAN: So 17.1% of adults over the age of 20 which is a little below 1 in every 5 adults in the United States reported that they are currently on the special diet. And when we ask this question we are actually looking specifically for people who are on a diet on the day that we they were interviewed, so these estimates are lower than what you might expect if you had instead asked people if they had been on a diet within the past month or past year.

HOST: I see. How does this percentage compare to past years? Do we have any data on that?

BRYAN STIERMAN: So as part of this report we also looked at special diets not just in 2015 to 2018 but over the entirety of the last 12 years, so the first couple of years we looked at were 2007 and 2008 and about 14% of adults were in the special diet at that time and that increased to 17% by 2017 to 2018. And while this increase of 3% of adults might sound relatively small it in fact actually represents millions of adults in the United States.

HOST: OK then, does the study get into why people go on these special diets?

BRYAN STIERMAN: To some extent yes we actually we did find out kind of why people were going on these. So the way that we get at that is that we ask NHANES participants what specific kinds of special diets that they were on so the kind of diet that they report using gives us a clue as to why they might have been on the diet. So to give you an example the most common kind of special diet that was reported in survey was a weight loss or low calorie diet. That was reported by about 9% of adults and obviously you would expect that people report this type of guy at her on this type of diet to try to lose weight. Another kind of special diet is a diabetic diet and this would be used by people with diabetes to help control their diabetes. Couple of others – so gluten free diets are generally used by people who have celiac disease though not exclusively. And then sometimes people would undertake a low salt diet in order to help control hypertension. So again the types of special diets set that people are answering are kind of giving us some clue as to why they might have been only in first place.

HOST: In your findings what kind of differences did you find among men and women and among different race ethnic groups?

BRYAN STIERMAN: Yeah so we did find differences in these categories. So we found that women were more likely to be on a special diet than men and this was by a significant margin. So about 19% of women compared to about 15% of men recorded special diet use. And with regards to race and ethnicity we found that non-Hispanic white adults were more likely to be on a special diet than non- Hispanic black and non-Hispanic Asian adults and Hispanic adults were somewhere in the middle but didn’t really differ significantly from the other race and ethnicity groups.

HOST: OK and what about data on children and adolescents? Do you have anything on special diets on those groups?

BRYAN STIERMAN: So we didn’t specifically study children and adolescents for this report but that data is available. So the dietary questionnaire or dietary interview that’s done within NHANES is done on all ages so certainly children and adolescents could be also looked at with regards to this in the future.

HOST:  Is there any other relevant point you might want to add that I’ve missed?

BRYAN STIERMAN: I think there are a couple things that I might want to mention. One is that we also looked at how dietary special diet use relates to obesity and what we found is that special diet use is actually highest among people with obesity at about 23% and those are overweight, about 17% of people were on a special diet. And then among those who were normal weight or underweight the lowest use of special diets, they had the lowest use of special diets, which is about 8%. And I think it’s interesting to note that the special diets have increased over time as I mentioned but also that obesity and obesity related diseases have increased over time so the use of special diets may be related to this, these changes in obesity and obesity related health conditions. But we didn’t study this specifically so it’s possible that there may be other explanations as well. And just kind of like a final recap – the main kind of big picture to get out of this is that many adults in the US are on a special diet and that this has increased over time and that future studies could actually use the wealth of NHANES data to look more closely at associations of special diet use with medical conditions and nutritional data.

HOST: Great. Well thanks very much for joining us Dr. Stierman.

BRYAN STIERMAN: Yeah thanks for having me.

HOST: Thanks again to Dr. Stierman for joining us today. The study is featured in a new Data Brief entitled “Special Diets Among Adults: United States, 2015-2018,” and was released on November 3. The Data Brief can be accessed at www.cdc.gov/nchs.

On November 4 of this week, NCHS released another study which focuses on chronic pain among adults in the United States, using data from the 2019 National Health Interview Survey. The study showed that 1 in 5 adults in the U.S. have experienced chronic pain over the past three months. Over 7% of adults had what is called “high impact chronic pain” – that is, pain that frequently limits life or work activities. Not surprisingly, the percentage of people who experience chronic pain and high impact chronic pain rises with age, as nearly one-third of people age 65 and over have experienced chronic pain in past three months, according to the study.

The new Data Brief, entitled “Chronic Pain and High-Impact Chronic Pain Among U.S. Adults, 2019,” show that women were slightly more likely than men to experience any type of chronic pain in the past three months, and that non-Hispanic white adults were more likely than other race/ethnic groups to experience chronic pain. Non-Hispanic Asian adults were significantly less likely than other race/ethnic groups to experience chronic pain in the past three months.

The study also showed that people living in rural areas were more likely than those in urban areas to experience any type of chronic pain. Over 1 in 10 people living in non-metropolitan areas experienced high impact chronic pain in the past three months, compared to 6% of people living in large central metropolitan areas.

The new Data Brief is available on the NCHS web site at www.cdc.gov/nchs.