This study has documented important increases in snacking behavior across all child age groups during the last three decades. Children in the U.S., especially the young, are consuming almost 3 snacks per day, and snacking accounted for up to 27% of the daily caloric intake in 2006. Our results showed major rises in snacking prevalence and caloric intake from 1989–91 to 1994–98 and again from 1994–98 to 2003–06. Important shifts towards more salty snacks and candies have been reported, although sweetened beverages and desserts remained the major snacking sources.
Previous studies in children and young adults found that the contribution of snacking to the total energy intake accounted for up to 25% and 23% respectively in 1996 (19
). These studies also reported an increased trend in the total calories coming from snacks, and the total number of snacking occasions. Our results are consistent with trends from previous research, except for the important jump in snacking behavior in this decade.
Some important key issues related to the energy intake showed interesting trends over the years studied. First, the energy density of snacks were constant over the years studied. Other findings in young adults reported an increasing trend until 1996(20
). Additional components of the increased energy intake from snacking are the grams and calories consumed per snack event (21
). We reported increased portion sizes of snacks in terms of grams; however, because of the increased intake of caloric beverages, there was a small decrease in calories per snack in the 1994–98 to 2003–06 periods, consistent with earlier studies (22
). However, without further research, it is unclear if this most recent period represents a shift toward lower portion sizes, or just the combination of more smaller snacks and more caloric beverages overall. Furthermore, there is minimal evidence on the health effects of these snacking changes (23
This study found a meaningful increase in intake of energy dense salty snacks and candies as sources of snacking energy. Also, children are consuming more beverages, such as fruit drinks, sport drinks and fruit juice, while decreasing fruit as a snacking source. Desserts remained as the major snacking source (cookies, cakes, etc.), consistent with previous works (20
). However, the smaller less representative Bogalusa Heart Study found in children aged 10 years old decreasing grams consumed from fruit juices and fruit, desserts and candies from 1973 to 1994 (25
These results may differ because snack and meal definitions have not been clearly established. In our study, we defined snacks as eating occasions outside meals. Foods defined as snacks, but consumed with a meal were recoded as meals. We also combined all the snacks consumed within 15 minutes as one snacking event. A small proportion of foods with missing designations of eating occasions were assigned first to meals, and the remaining were considered as snacks (there was a small effect of a shift in prevalence of less than a tenth of a decimal place). This conservative definition allowed us to define three principal meals and then study snacking outside of meals for all the years surveyed. Different authors have defined snacks according to the name identified by the respondent, time of day, type of food, or even snacking foods have been counted as single eating occasions within a unique time interval (26
). Although there is no current consensus about snacks and meal definitions, our approach may be more linked to the way we understand the metabolic consequences of foods eaten together at one short period occasion.
Days of intake surveyed may also be influencing disparities between studies. To be consistent, we used two days of intake to create comparable measurements over time. This allowed us to have a closer approximation of usual intake. Further, we found that the third day of snacking data for the two earlier studies were different, and probably represent underestimates of snacking. The Nationwide Food Consumption Survey 77–78 and the Continuing Survey of Food Intake by Individuals 89 reported that only 4% of subjects had snacks on day 3 and this last day is suspected to be greatly underreported (19
Other limitations inherent to this study are related to the use of different surveys. Changes from the 80’s to the 90’s have been important, although subsequent changes in the number of passes and probes have been much smaller. As with all USDA surveys, the National Health and Nutrition Examination Surveys 2003–2006 methodology is the same as the Continuing Survey of Food Intake by Individuals developed by USDA since the surveys were merged with USDA in the lead on the diet component (14
). This was the reason for adding the second day of dietary record for the National Health and Nutrition Examination Surveys beginning in 2003. Unfortunately no bridging study between the 1980’s and 1990’s nor between the 1990 and 2003–6 surveys methods exists as was undertaken earlier by USDA(29
). The UNC-CH food grouping system developed by this UNC team was used to link different foods coded and collected in the first survey with the foods consumed in the last periods, ensuring consistently high-quality estimates of nutrient values over time (16
In conclusion, our findings suggest that children of all ages from 2 to 18 are experiencing important increases in snacking behaviors and are moving toward a consumption pattern of 3 meals plus 3 snacks per day. This issue questions whether the physiological basis for eating is being dysfunctional as our children are moving toward constant eating.