Views of nature influence sugar consumption and delayed gratification

Relation

Kao CC, Wu WH, Chiou WB. Contact with nature can lead to less discounting and healthier dietary choices.J Environ Psychol. 2019;65:101333.

Study objective

To determine the influence of natural and urban landscapes on sugar consumption, mediated by temporal discounting (the tendency to discount larger future benefits relative to immediate smaller gains, i.e., preferring immediate gratification over delayed gratification).

Participant

The study involved 93 undergraduate students at a Taiwanese university (mean age 20.9 years, 51.6% female) with a desire for weight loss. Researchers collected information about their motivation to lose weight, time since last meal and current body mass index (BMI). Exclusion criteria included a history of an eating disorder and current participation in a weight loss diet (including dietary modification and use of weight loss supplements).

Draft

Participants were randomly assigned to 1 of 3 viewing conditions in which they viewed scenes on a laptop computer screen that corresponded to 1 of 3 landscape viewing types: natural, urban, or controlled. In each condition, a sequence of 6 scenes was displayed, and each image was displayed for 1 min. Participants were instructed to “immerse themselves in the environment shown in each picture.”

Participants then completed a temporal discounting measure (see below) as well as a psychological personality test to disguise the purpose of the experiment until after the study was completed. Finally, participants received a “participation reward” of bubble tea with an optional addition of sugar.

Target parameters

• Zeitliche Diskontierung (TD): Ein wichtiges Maß bei der Bewertung von Gesundheitsverhaltensentscheidungen. TD bewertet die Abwertung zukünftiger Vorteile durch eine Person für unmittelbarere Belohnungen, dh die Bevorzugung einer sofortigen Befriedigung gegenüber einer verzögerten Befriedigung.¹
  • In der Studie beantworteten die Teilnehmer hypothetische Fragen zum Lottogewinn in verschiedenen Dollarbeträgen – z. B. „Wenn Sie gewinnen würden, würden Sie jetzt lieber 2.000 Dollar oder in einem Jahr 4.000 Dollar haben?“ Aufeinanderfolgende Fragen mit unterschiedlichen Beträgen identifizierten einen bevorzugten „Abzinsungssatz“ für jeden Teilnehmer, von 0 (keine Abzinsung) bis 1 (vollständige Abzinsung, dh der Teilnehmer wählt immer eine sofortige Belohnung).
• Zuckermenge (SA): Die Teilnehmer konnten selbst auswählen, wie süß ihr Belohnungs-Bubble Tea war (dh wie viel Zucker darin enthalten war), von 0 (kein Zucker) bis 5 (normaler Zucker).

Key insights

Viewing conditions had a small but statistically significant effect on both temporal discounting and sugar amount, with further analysis showing that the former significantly influenced the latter. Special:

• Teilnehmer, die Naturszenen betrachteten, hatten eine um 17,5 % niedrigere mittlere TD als Teilnehmer in den städtischen (P=0,014) und Kontrolle (P=0,029) Gruppen.
• In ähnlicher Weise hatten Teilnehmer, die die Natur betrachteten, eine um 19,1 % niedrigere SA als Teilnehmer in der Stadt (P=0,013) und Kontrolle (P=0,017) Gruppen.
• Die Mediationsanalyse hat gezeigt, dass:
  • Naturbetrachtung war ein signifikanter Faktor bei der Vorhersage von TD (B=−0,18, SE=0,06, t=-2,749, P=0,007);
  • TD war ein signifikanter Vorhersagefaktor bei der Bestimmung von SA(B=2,83, SE=0,45, t=6,347, P<0,001);
  • Naturbetrachtung war nur dann ein signifikanter prädiktiver Faktor bei der Bestimmung von SA, wenn TD in die Analyse einbezogen wurde (B=−0,95, SE=0,33, t=-2,885, P=0,005).
• Schließlich beeinflusste die Naturbetrachtung auch die zuckerfreie Option signifikant (dh SA = 0), aber nur, wenn TD in die Analyse einbezogen wurde (B = 1,32, SE = 0,50, Z = 2,638, P=0,008, Wald=6,956).

All conditions were statistically equivalent in motivation to lose weight, time since last meal, and BMI. There was no difference between male and female participants in terms of outcomes.

Practice implications

The ability of views of nature to influence physiological and psychological states is well established.^2-4This study is one of the first to link the presence of nature to changes in health behavior (in this case sugar consumption) and to propose an explanatory mechanism (temporal discounting).

Health behaviors (that is, the decisions we make and the actions we take regarding our health) determine 30% to 50% of our health status.⁵Some of the most influential “determinants of health” are by far our diet and dietary choices. This is particularly true for chronic diseases such as cardiovascular disease, diabetes and obesity, which have a well-established and obvious relationship to diet, both calorically and nutritionally.

One of the biggest influences of dietary decisions is the tendency to engage in “temporal discounting,” or the reduced ability to delay gratification.⁶It is a common experience to enjoy immediate rewards (e.g. eating sugary "junk" food) despite knowing that there will be future consequences (e.g. weight gain). This penchant for unhealthy short-term gains with resulting long-term detrimental effects is a major contributor to individual health conditions and the modern epidemic of many chronic, diet-related diseases.

The environment influences every aspect of our health, including conscious and subconscious decisions that affect health behaviors.

The predominant mechanism linking environmental perceptions to health outcomes, possibly including sugar consumption, evokes an evolutionary perspective. Natural scenes are known to promote psychophysiological relaxation through evolutionarily derived “biophilic” responses.^7.8Over millennia, our species has evolved to relax the body and mind when encountering the natural “base” environment of our prehistoric ancestors.^9.10

In this study, the presence of nature compared to urban or control views may have shifted autonomic nervous system (ANS) activity into a parasympathetic state, away from more sympathetic dominance, thereby reducing energy metabolism and the (unconscious) desire for available “quick energy.” if fight or flight becomes necessary. Several studies have demonstrated ANS responses to similarly designed interventions.^11,12Although the short duration of this study makes detection of hormonal changes impractical, it is possible that the interest in metabolically available sugar was also influenced by neuroendocrine changes, as shown in other studies.^13-15These mechanisms may explain the relationship between nature viewing, temporal discounting, and sugar consumption by modulating feelings of hunger and satiety as well as cognitive function and health behavior decision making. Further research in this area is needed to identify causal pathways.

This study had its limitations. The researchers did not conduct a pre-post comparison of outcome measures, so although there were no differences between groups in time since last meal, BMI, or motivation to lose weight, it cannot be ruled out that people in the nature group dida prioriTrends toward lower TD and/or SA. Future studies may want to standardize these factors between groups prior to experimental exposure to best determine whether the variable is responsible for the measured effects.

Additionally, the researchers didn't ask participants why they chose their sugar reward amount, so it could be that TD had nothing to do with it. Future studies could address this, although it is also possible that nature-induced TD is an unconscious process, as is the case with other nature-related mental-emotional effects such as mood, attention, memory, etc. Finally, this was a pilot study of 93 Taiwanese students; Larger studies with more diverse sample populations would increase the generalizability of the results.

Conclusion

The environment influences every aspect of our health, including conscious and subconscious decisions that affect health behaviors. In particular, this study suggests that exposure to natural landscapes may be helpful in reducing sugar intake in adolescent populations at risk for obesity, diabetes, cardiovascular disease, and other diet-related diseases. Combined with existing research showing measurable effects on physiological and psychological states, it is becoming increasingly clear that exposure to stimuli from the natural environment can make a fundamental contribution to human health.