Stunkard et al 1990 & Forslund et al 2005 By: Kendra Elderkin, Divya Raj, Haley Albaum, Sarah Rosemont

Stunkard et al 1990

Stunkard’s Evolution hypothesis of obesity Humans are genetically programmed to eat when food is available in order to store fat for times when food is scarce. Due to today’s abundance of food, more people are becoming obese because their eating habits have not evolved.

Aim: to discover to what extent genetics impact concordance rates of obesity between twins. Participants: monozygotic and dizygotic male twins, reared together and reared apart; opportunistic sample

Method/Design -Researchers tested each participants height, weight, and BMI -First test was administered when participants were 20 years old, then a follow up test was given at age 25 -Concordance rates were measured between each participant and their twin

Results -Height, weight, and BMI were highly correlated between twins (reared together and apart) -Stronger concordance of higher BMI between monozygotic twins than dizygotic twins

Discussion -Human BMI is under substantial genetic control -Environment has little to no influence

Evaluation Strengths: -strong variable control (genetics) -lab setting -reductionism Weakness: -correlation does not mean causation -reductionism -adoption agencies often place separated twins in similar environments

C.E.G.M C- All participants were British E- Informed consent, discomfort in revealing BMI G- Gender differences were not acknowledged M- Correlation does not mean causation

Implications Psychological: -Nature vs. Nurture debate -Wadden (1993) Social: -Heritability of obesity and BMI

Connections Biological LOA: -behavior is genetically innate (basic principle) -Bouchard twin studies -Nature vs. Nurture debate Cognitive LOA: -Schemas influence healthy habits and ultimately BMI Socio LOA: -Societal views on health and personal well-being influence an individual's BMI

B- biological influence on an individual’s BMI (genetics) M- monozygotic twins had stronger concordance rates of higher BMI I- individual differences were not acknowledged (correlation does not mean causation)

Forslund et al 2005

Aim/Method/Procedure ●Aim: Studied the relationship between snacking and Body Mass Index (BMI). ●Method/Procedure: Self-Reported (through a survey/questionnaire). Participants were given a survey that asked them to self-report how frequently they ate, taking note of what foods they were consuming and at what time of the day. The participants were also asked to record their physical activity throughout the day.

Results ●Those who snacked more frequently (approx. 6 times a day) had a higher BMI than those who snacked less. ●Exercise, type of food, and time of consumption all affected the participant’s body weight.

Discussion ●People’s bodies are not able to fully compensate from the extra input of energy into their bodies from snacking. ●People are more likely to consume savory foods right before lunch, dinner, and around 10pm. ● People who consumed food late at night and right before a larger meal gained more weight that those who did not snack at those times. o Body’s metabolism slows down and activity decreases at night and after a large meal ●People who spent more of their idle time moving and exercising tended to have a lower BMI than those who spent it sitting around and consuming food.

Strengths & Weaknesses ➔ Strength: Takes into account both male and female participants ➔ Weakness: Since the participants self- reported the data, they could have fabricated their results to make them appear healthier than they truly were.

C.E.G.M. Culture: ●Study done in a modern industrialized culture and therefore does not take into account the eating habits of those living in more rural areas. Ethics: ●Intruding on people’s personal lives. ●Everybody’s body works differently, so it is not fair to group everybody into the same category for the purpose of this study. Gender: ●Both male and female participants were used in this study. Females were found to snack more frequently than males. Methodology: ●Participants self-reported the data through a survey.

Connections to LOA 1.Biological: Release of serotonin when you consume certain foods. 2.Cognitive: Schema theory – If someone has found comfort from food in a tough situation in the past, they could continue to use the consumption of food as a coping mechanism because they will associate food with solving their problems. 3.Sociocultural: Bandura’s social learning theory- If someone is constantly observing another individual snacking between meals, they are more likely to imitate that behavior and increase their snacking.

Works Cited Graaf, Cees D. "Effects of Snacks on Energy Intake: An Evolutionary Perspective." (n.d.): n. pag. Sciencedirect.com. Division of Human Nutrition, Wageningen University, 25 Nov Web. 2 Dec "The Body-Mass Index of Twins Who Have Been Reared Apart — NEJM." New England Journal of Medicine. N.p., n.d. Web. 02 Dec