Dieting What is dieting Dieting is no longer known what is was once before it is now known to be o A severe restriction of calorie intake o Intentional restriction of caloric intake for the purposes of weight loss o These are considered testimonial and just because their diet works for them does not How do we know dieting works Ask your friends Ask your family mean it will work for you o Review the research College Students Dieting and Weight Slightly over 40 of females describe themselves as overweight Over 70 of women report dieting and desiring weight loss Nearly 40 of men report dieting and 35 report desiring weight loss About 12 of men describe themselves as overweight Key point A much larger percentage of men and women describe themselves as overweight than men and women who really are overweight The Minnesota Starvation Experiment A very early longitudinal experimental study involved 32 healthy male subjects without a history of eating disorders They were asked to reduce their intake to achieve 75 of medically ideal weight o Men were subjected to semi starvation Subjects were studied for a 12 week control period 24 weeks of semi starvation average loss of 24 of initial body weight Some were followed up to 12 months o What they found When the subjects were exposed to food they often binge ate and hoarded food and these effects lasted beyond weight restoration Caloric deprivation resulted in irritability intense preoccupation with thoughts of food decrease in self initiated activity loss of sexual drive o Consequences Decreased BMR Decreased respiration slowed pulse lowered blood pressure and decreased temperature symptoms of AN Increased depression introversion apathy Food related obsessions and rituals Binge eating episodes began 29 of the men when the diet ended For some men this overconsumption led to vomiting and one man required hospitalization after excessive food intake Binge eating may represent a behavioral mechanism to prevent weight loss The Minnesota Starvation Experiment and Dieting Today Set Point Theory o Suggests that body weight is regulated at a predetermined or preferred level by the hypothalamus famine o Explains why organisms resist weight change o Our bodies have evolved weight defending mechanisms in order to withstand periods of o The body is more efficient in protecting against weight loss during caloric deprivation compared to conditions of weight gain overeating o Such mechanisms could be triggered by dieting and make weight loss more difficult than portrayed by weight loss programs How is research with people conducted o Randomized trials include a control group where individuals are randomly assigned to a diet condition or to a no diet condition and then followed over time o Observational studies do not include control groups so no causal conclusions about the effects can be drawn from them It is much more difficult to perform randomized trials i e it is difficult to require obese individuals with an interest in dieting to remain in wait list control groups for extended periods of time Research from dieting studies o Most randomized studies found no change in diet versus non diet group after 2 or 3 years Mann et al 2007 o The most promising results involved a lifestyle intervention involving diet and exercise Diabetes Prevention Program Research Group 2002 o Patients in a hypertension study slight reduction in blood pressure over 3 years maintained 4 lb weight loss some stayed off meds diet required sodium alcohol reduction Mann et al 2007 Why is it difficult to get effective dieting research o Follow up rates are low 33 and generally those that do better on weight loss maintenance o Weights were self reported usually some bias o Some studies don t ask about exercise habits o Some studies don t ask about participation in other diets Can dieting be counterproductive o Most undereaters develop intense feelings of deprivation nutritional psychological and become correspondingly vulnerable to temptations to abandon the diet temporarily or permanently Herman van Strien Polivy 2008 o Pink elephant effect For the next 10 seconds try not to think of eating a piece of cake o Paradoxically it may be the cognitive effort not to think about eating that places one at risk for eating Weight loss programs o Less than 7 of members remain after 1 year Finley et al 2007 and weight loss is correlated with attendance and whether the members stay with the group Djuric et al 2002 Heshka et al 2003 o Showed higher rates of body dissatisfaction Goldstein et al 1996 o Reported high levels of dietary restraint o Reported high levels of weight shape and eating over concern o Reported significantly higher levels of emotional eating levels than others o Over 70 reported bingeing in the past 3 months Green Buckroyd 2008 o May increase the risk of eating disorders due to increased focus on body weight stimulus control ie if I m around food I should avoid it and dietary restriction Research on college students o Subjects consisted of 20 overweight and 20 normal weight undergraduate dieters o After dieting subjects participated in an ice cream taste test What he found Overweight subjects who stayed on their diets ate almost twice as much as overweight subjects who went off their diets o In the next study he put a short term food restriction on some students and didn t put a restriction on others What he found After 2 days restricted subjects ate more ice cream than unrestricted subjects in his lab o Over 4200 undergraduates completed an online survey measuring eating disorder behaviors and attitudes demographics were also collected Overweight participants were more likely to engage in dieting behaviors These students were also more fearful of bingeing and more preoccupied with food Dieting and Eating Disorders diet Girls who dieted were eight times more likely to develop an eating disorder than girls who didn t Most cases of AN begin when the person begins a weight loss diet Dieting most often predicts and precedes binge eating among adolescent girls Most patients with BN diet before binging Peers dieting and eating disorders o The importance that peers put on weight and eating is most strongly related to weight concerns in elementary school and middle school girls o Other factors that contribute to weight concerns include Trying to look like girls women on TV and in magazines Body mass index BMI Confidence middle school only Being teased about weight middle school only 1998