Effects of diets and their role in weight control
Department of Psychology, University of Oviedo, Oviedo, Spain. Psychology Health and Medicine
(Impact Factor: 1.26).
06/2007; 12(3):321-7. DOI: 10.1080/13548500600621545
This study examines the secondary effects of hypocaloric diets. The results show that the positive short-term effects with regards health are not maintained in the long term, as most people eventually return to their original weight. A description is given of how psychological reasons are more important than biological mechanisms when explaining this failure and stress is put on how carrying out successive hypocaloric diets can result in a subgroup of people becoming overweight or obese. Furthermore, an analysis is made of the relationship between diets, eating disorders and the "yo-yo effect", which is in turn associated with a rise in morbimortality due to a wide range of causes. As an alternative to the indiscriminate use of hypocaloric diets, a strategy based on the modification of lifestyle is suggested in order to control weight and improve health.
Available from: Marie Hennecke
- "This increased dietary intake may be caused by physiological needs that have to be met after periods of food deprivation. It may, however, also be caused by psychological reasons (Amigo & Fernandez, 2007). In this research, we examine one such psychological factor, namely how viewing one's own weight loss with a focus on the process level of goal pursuit (as having dieted well; process focus of success) or with a focus on the outcome level of goal attainment (as having achieved weight loss; outcome focus of success) influences the effects of prior weight loss on subsequent weight loss. "
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Dieters often show weight cycling, i.e. prior successful weight loss is followed by weight gain. The current study examined how goal progress during a diet (i.e. weight loss) impacts subsequent weight loss depending on whether success is identified on the process level or the outcome level of dieting.
A short-term longitudinal study examined lagged effects of weight loss and identifications of success in one week on weight loss in the subsequent week. Across 6 weeks, N = 126 overweight women reported their weekly weight and the degree to which they considered themselves as successful regarding the process of dieting (e.g. changing eating behavior) and the desired dieting outcomes (e.g. improving appearance).
Successful weight loss in one week negatively affected weight loss in the subsequent week. However, identifying success on the process level reduced this negative effect.
Although people might feel generally that goal progress licenses subsequent goal-inconsistent behavior, identifying successful goal-pursuit on the process rather than the outcome level of a goal may counteract the subsequent loss of dieting motivation.
Available from: PubMed Central
- "Especially for short-term weight management program, a caution is always necessary to avoid side effects of weight loss like yo-yo effect or developing an eating disorder (e.g. anorexia nervosa, bulimia)  so establishing good nutrition habits which have long term effects on maintaining good overall health as well as appropriate body weight should be a primary focus in validating an efficacy of those weight-management programs. "
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ABSTRACT: The purpose of this study was to investigate whether elective course work based nutrition education in university can change students' body composition and eating habits associated with obesity and its related health risk in first-year college students. A total of 38 students agreed and participated in the study. Participants received a series of lecture about obesity, weight management, and concepts of nutrition and food choices for 13 weeks. The students' BMI and body composition, including body fat and muscle contents, were measured. A 24-hour diet recall for two days was performed for food intake analysis, and the questionnaires for dietary behaviors were collected at the beginning and the end of the study. Paired t-test and χ(2)-test were used for statistical analysis. Data showed that most of the anthropometric parameters including body weight were not significantly changed at the end of the coursework. Interestingly, skeletal muscle contents in both obese (BMI ≥ 23) and lean (18.5 ≤ BMI ≤ 22.9) subjects were significantly increased. Total energy intake was decreased in total subjects after the study. Also, general nutrition behavior of the subjects including enough hydration and utilization of nutrition knowledge were significantly improved during the study period. The total number of responses to doing aerobic exercise was slightly increased after the study, but the average frequency of exercise in each individual was not changed. These results suggest that class-work based nutrition education on a regular basis could be a time and cost effective method for improving body composition and nutritional behavior in general college students.
Available from: Catherine Jensen Pena
- "As stress and the stress hormone corticotropin-releasing factor (CRF) are known promoters of increased consumption of calorically dense foods, reprogramming of stress circuitry may be a central mechanism driving repeated dieting, or the " yo-yo " effect, resulting in an increased risk for greater weight gain and later obesity (Epel et al., 2001; Dallman et al., 2006; Amigo and Fernández, 2007; Teegarden and Bale, 2008). Stress-induced activation of the hypothalamic–pituitary–adrenal (HPA) stress axis and release of CRF increases reward-seeking behaviors (Dallman et al., 2005; Ghitza et al., 2006). "
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ABSTRACT: Long-term weight management by dieting has a high failure rate. Pharmacological targets have focused on appetite reduction, although less is understood as to the potential contributions of the stress state during dieting in long-term behavioral modification. In a mouse model of moderate caloric restriction in which a 10-15% weight loss similar to human dieting is produced, we examined physiological and behavioral stress measures. After 3 weeks of restriction, mice showed significant increases in immobile time in a tail suspension test and stress-induced corticosterone levels. Increased stress was associated with brain region-specific alterations of corticotropin-releasing factor expression and promoter methylation, changes that were not normalized with refeeding. Similar outcomes were produced by high-fat diet withdrawal, an additional component of human dieting. In examination of long-term behavioral consequences, previously restricted mice showed a significant increase in binge eating of a palatable high-fat food during stress exposure. Orexigenic hormones, melanin-concentrating hormone (MCH) and orexin, were significantly elevated in response to the high-fat diet only in previously restricted mice. Furthermore, administration of the MCH receptor-1 antagonist GSK-856464 [4-(4-ethyl-5-methylsulfanyl-1,2,4-triazol-3-yl)pyridine] significantly reduced total caloric intake in these mice during high-fat access. These results reveal reprogramming of key central pathways involved in regulating stress responsivity and orexigenic drives by moderate caloric restriction experience. In humans, such changes would be expected to reduce treatment success by promoting behaviors resulting in weight regain, and suggest that management of stress during dieting may be beneficial in long-term maintenance.
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