Preventing weight gain in the population will require changing both diet and physical activity patterns. We have argued that this can best be done through small lifestyle changes that are more feasible to achieve and sustain than larger lifestyle changes [10
]. We have demonstrated that a small changes message to increase physical activity by 2000 steps/day results in significant increases in daily walking [16
This is the first demonstration that recommendations to reduce energy intake by about 100 calories per day along with tips and ideas for doing this results in significant reductions in total daily energy intake. Further, energy intake was reduced more at the meals where the tips were used than at meals where the tips were not used. When combined with the message to increase daily steps, this strategy should be effective in preventing weight gain. The daily increase of about 1454 steps equals approximately an additional caloric energy expenditure of about 70 calories per day. The mean daily intake during the intervention week was reduced by about 300 calories per day, suggesting that the small changes recommendations were feasible, easy to understand and to implement.
The participants were encouraged to reduce their caloric intake by about 100kcal/day; interestingly, it appears that the daily intake was reduced by an additional 200 calories. It is possible that the small changes message is more helpful and feasible than rigorous diet restrictions and therefore encourages participants to apply more than just one small-changes tip into their daily lifestyle which results in an even larger reduction of caloric intake than suggested.
During the intervention week, reductions were seen in each macronutrient and in sugar and sodium. Interestingly, less sugared soda was consumed during the intervention week, and this was one of the most popular options for reducing energy intake. Another popular message was just leaving 3–4 bites of food on the plate, perhaps because this option does not require the individual to completely give up favorite foods. It was interesting that although subjects reported often selecting the option of choosing fruits and vegetables over higher caloric snacks, the results indicate no differences in fruit and vegetable consumption between the two weeks. It is not clear if the participants failed to actually increase fruit and vegetable intake or whether the changes were too small to detect with our methods.
From the diet diaries, we can conclude that during the intervention week, participants were eating a diet similar to their usual diet with the exception that meal sizes were smaller. This, in turn, resulted in less total energy intake over the day. Meal frequency did not change in the intervention week, indicating that skipping meals was not used to reduce energy intake.
This study is to our knowledge, the first study that has attempted to measure small changes in total energy intake using diet diaries. Diet diaries have been widely used to investigate the nature of influences on food intake in free-living humans [26
] and research suggests that three to seven days of recording is sufficient to obtain accurate information of the individuals’ overall daily intakes [29
]. In the diet-diary method by de Castro [21
], participants were asked to record in a pocket-sized diary their eating behavior, and the environmental context in which they eat and drink for seven consecutive days. There seems to be a good agreement between diary records and the actual amounts eaten [31
] and comparisons of self-reports of intake and the actual food ingestion revealed agreements of about 87% between the diary records and the actual amounts eaten [33
]. Using observers to write down the participants’ food intake and comparing it to the participants’ record showed truthful and valid records [34
]. While underreporting of food intake does occur with the diet diary method, especially in overweight participants [35
], it is expected to be consistent within groups and thus, analysis within groups comparing baseline with intervention weekly dietary intake seems appropriate [42
]. In addition, in the present study, participants who reported intake that fulfilled an operational definition of suspected underreporting were eliminated from the analysis.
One limitation of this study is the convenience sample of both university and non-university employees which included mainly women and therefore cannot be generalized. As in most health and diet related studies, mostly middle-aged women were interested in participating compared to younger women and men. In addition, it was not possible to determine whether the participants altered their food intake due to the small changes program or due to other potential factors such as a close food monitoring or more extreme habit changes. A possible placebo effect might have taken place if the program only worked because the participants believed it would work for them. However, the eating behavior of the participants changed as hypothesized and it appears that this type of intervention could be a successful tool to reduce energy intake. Although this study was not sufficiently long to see effects on weight gain, we have shown that the small changes approach can significant reduce weight gain in overweight and at risk for overweight children over a period of 6 months [18
]. These results add to the body of research supporting the small changes approach to modifying energy intake, energy expenditure and preventing excessive weight gain [10