EXPLANATIONS FOR THE SUCCESS AND FAILURE OF DIETING
The quest to understand the nuances of dieting success and failure has led to the development of various models, with the Spiral Model and Ironic Process Theory offering insights into the psychological complexities involved. These models and the previously discussed Restraint Theory, Disinhibition, and Boundary Model provide a comprehensive overview of why dieting efforts often falter.
The Spiral Model
Heatherton and Polivy's Spiral Model captures the cyclical nature of dieting, emphasizing the psychological aftermath of dieting failures. This model suggests that initial dieting attempts, often sparked by body dissatisfaction and low self-esteem, lead to a temporary phase of success. However, due to the difficulty of achieving lasting weight loss, many individuals face repeated failures, reinforcing negative self-perceptions and leading to further dietary restrictions. This cycle of restriction, failure, and emotional distress exacerbates the problem, making successful weight loss increasingly elusive.
Ironic Process Theory
Wegner's Ironic Process Theory provides a psychological explanation for the preoccupation with food that plagues many dieters. By attempting to suppress thoughts of certain foods, individuals inadvertently make them more salient in their minds, leading to an increased likelihood of overeating. This theory illustrates the counterproductive nature of dietary restrictions, showing how the effort to avoid specific foods can intensify cravings and lead to diet failure.
RESEARCH: THE TRUBY ET AL. (2006) STUDY
Truby et al. conducted a six-month trial evaluating the effectiveness of various diets among obese participants, a study highlighted in a BBC documentary. Participants were assigned to one of four diets: Slim-Fast Plan, Weight Watchers, Dr Atkins' New Diet Revolution, or Rosemary Conley's Diet and Fitness Plan, with a control group receiving usual care. Results showed significant weight loss across the diets, particularly noting that fewer participants continued with the Atkins or Slim-Fast plans than Rosemary Conley and Weight Watchers.
Evaluating the Theories
The Spiral Model and the Ironic Process Theory highlight important psychological factors contributing to the difficulty of sustained dieting success. However, these theories also raise questions about how some individuals overcome these challenges and achieve their weight loss goals.
Contributions and Limitations:
The Spiral Model and the Ironic Process Theory illuminate the common pitfalls of dieting, emphasizing the role of psychological and emotional factors in dieting outcomes. They suggest that interventions focusing solely on food restriction without addressing underlying psychological issues may be doomed to fail.
Research supporting these theories, such as the studies by Adriaanse et al. and Heatherton and Polivy, underscores the complex relationship between dieting intentions and behaviours. However, these models do not fully account for the diversity of dieting experiences or explain why some individuals succeed despite the challenges outlined.
The concept of locus of control offers a potential explanation for individual differences in dieting success. It suggests that those with an internal locus of control, who see their weight loss efforts as under their control, may be more likely to achieve lasting success.
ALTERNATIVE REASONS FOR THE FAILURE OF DIETING
EXPLANATIONS FOR THE SUCCESS OR FAILURE OF DIETING
Dieting encompasses adopting specific eating patterns to achieve weight loss or health goals. Despite good intentions, driven by societal norms and health aspirations, diets often fail for a long time. This complexity arises from biological, psychological, and environmental factors.
THEORY 1: THE IMPACT OF DIETARY CHOICES
Gary Taubes (2006) posits that a diet's effectiveness hinges not on calorie intake but on the types of food consumed. He critiques the common strategy of reducing caloric intake, especially fats, as flawed because it neglects how carbohydrates affect the body. According to Taubes, Carbohydrates can lead to an overproduction of insulin, dubbed the "hunger hormone," which increases hunger and signals the body to store energy as fat. This biological response challenges the efficacy of low-calorie diets that don't address carbohydrate consumption.
RESEARCH SUPPORT:
Research on rats highlights how diets high in sugar, when abruptly ceased, can lead to withdrawal symptoms, indicating the addictive nature of high-carbohydrate foods. This addiction to carbohydrates is a critical barrier to successful long-term weight loss and maintenance.
THEORY 2: REDUCED METABOLISM DUE TO LOW-CALORIE DIETS
Eating significantly fewer calories can decrease metabolism as the body enters a "famine mode" to conserve energy. This evolutionary response slows down metabolic rates to preserve fat reserves and can lead to muscle loss. Consequently, when normal eating resumes, individuals often regain weight because their metabolisms remain suppressed.
THEORY 3: THE ROLE OF GHRELIN IN DIETING
Ghrelin, a hormone released by the stomach to signal hunger, plays a crucial role in the challenge of dieting. The levels of ghrelin increase with the time elapsed since the last meal, making hunger more pronounced during dieting. This increase can make it harder to maintain a diet and contributes to the common pattern of regaining weight after dieting.
GHRELIN AND ITS IMPACT ON APPETITE: INSIGHTS FROM RESEARCH
STUDIES ON GHRELIN
Cummings et al.'s research has been pivotal in understanding ghrelin's role in regulating appetite. In 2006, Cummings found that both animals and humans showed increased appetite when injected with ghrelin. Further studies by Cummings et al. (2004) involved monitoring human participants' ghrelin levels at five-minute intervals while participants reported their hunger levels every thirty minutes. In five out of six participants, a significant correlation emerged between ghrelin levels, stomach emptiness, and reported hunger, underscoring ghrelin's influence on appetite.
Additionally, interventions such as gastric bands, often used to manage obesity, have been observed to reduce ghrelin secretion, aligning with their role in appetite control. Patients with Prader-Willi syndrome, characterized by excessive hunger and obesity, exhibit elevated ghrelin levels, suggesting a direct link between ghrelin and hyperphagia (excessive eating).
CRITICAL EVALUATION OF GHRELIN RESEARCH
However, the research by Cummings et al. faces limitations, notably the small sample size, which restricts the generalizability of the findings. There's also a consideration that participants' self-reported hunger could be influenced by external factors such as mealtime expectations, hinting at cultural rather than purely biological determinants of hunger.
THEORY 4: THE ROLE OF ADIPOSE CELLS IN BODY WEIGHT REGULATION
An additional theory in understanding dieting success or failure relates to adipose cells, which store body fat. According to Le Magnen (1985), the number of adipose cells can increase with weight gain but does not decrease, potentially influencing the body's set point — a hypothetical weight the body aims to maintain. When adipose cells lack stored fat, hunger signals are activated; conversely, when they are filled, hunger subsides. This dynamic suggests that reducing and maintaining a lower body weight becomes challenging after gaining weight due to the body's natural inclination to refill these adipose cells, perpetuating hunger and complicating efforts to sustain weight loss.
THEORY 5: THE CRUCIAL ROLE OF LEPTIN IN DIET AND WEIGHT MANAGEMENT
Leptin is a pivotal hormone in regulating body weight, appetite, and energy expenditure. Produced primarily by fat cells, intestinal cells and the placenta, leptin acts as a signal to the brain to help regulate food intake and body fat. The hormone's name is derived from the Greek word "Leptos," meaning "thin," highlighting its association with maintaining body weight.
WHY IS LEPTIN IMPORTANT?
Leptin levels adjust in response to changes in body fat. For individuals with minimal body fat, leptin helps regulate weight by managing hunger and utilising stored energy. Conversely, in overweight individuals, leptin issues may arise, potentially leading to eating disorders and a slow metabolism. As body fat increases, leptin levels rise to signal the brain to reduce food intake and increase fat burning. When body fat decreases, leptin levels fall, signalling it's time to eat.
IMPACT OF DIETING ON LEPTIN
Dieting, especially when it involves significant calorie restriction, can decrease leptin secretion. This reduction occurs more rapidly than can be accounted for by body fat loss, just as overfeeding can increase leptin levels more quickly than fat gain suggests. This creates a challenge for those trying to lose weight, as lower leptin levels during calorie restriction lead to increased appetite, making sustained weight loss difficult. The hormonal drive to eat often overrides willpower.
LEPTIN RESISTANCE: A MODERN DILEMMA
Despite higher circulating leptin levels in overweight individuals, many fail to respond appropriately by curbing food intake—indicating a disruption in leptin signalling, known as leptin resistance. This resistance might be due to the downregulation of leptin receptors in the hypothalamus or blockages preventing leptin from reaching these receptors. Unlike wild animals, which maintain stable body composition through natural feeding behaviours, modern humans often exhibit leptin pathway disruptions due to deviations from evolutionary diets.
INSIGHTS FROM LABORATORY STUDIES
Studies of ob/ob mice, which lack leptin, and db/db mice, which lack leptin receptors, have provided valuable insights into leptin's role. Ob/ob mice exhibit uncontrolled appetite and obesity due to the absence of leptin but respond positively to leptin injections, normalizing appetite and body weight. Conversely, db/db mice do not respond to leptin injections, as they produce leptin but lack the receptors to process it, highlighting the importance of functional leptin signalling for weight regulation.
When leptin was discovered, there was great excitement about its potential to combat obesity by reducing appetite and food intake. For some, leptin supplements did curb hunger, but the high cost and variability in effectiveness, particularly among those with leptin resistance, limited their use. People with leptin resistance, akin to db/db mice with non-responsive leptin receptors, saw no benefit from additional leptin. The situation could worsen, as continuous exposure to high leptin levels might further desensitize the receptors.
Maintaining balanced leptin levels without inducing resistance involves several strategies:
Watch Your Sugar Intake: Studies in rats have shown that diets high in fructose can inhibit leptin receptors. Fructose consumption makes the hypothalamus less responsive to leptin and elevates blood triglycerides, which can block leptin's access to the brain. Consequently, rats on high fructose diets did not reduce their energy intake in response to leptin and gained more weight, especially when switched to high-fat diets.
Avoid Lectins: Lectins, particularly those in cereal grains like wheat, barley, and rye, may contribute to leptin resistance. Lectins can bind to leptin receptors, blocking the interaction between leptin and its receptor and potentially exacerbating leptin resistance. While high levels of lectins have been shown to affect receptors, it's still unclear whether typical dietary levels have the same impact.
Avoid Severe Calorie Restriction: Excessive dieting can lead to reduced leptin secretion quicker than expected from fat loss alone. This reduction in leptin makes maintaining or achieving leanness challenging, as the lower your body fat and leptin levels, the higher your appetite. This highlights the powerful influence of hormones over conscious willpower in regulating hunger.
For individuals with obesity and leptin resistance, carbohydrates, especially sugars and grains containing lectins, may hinder leptin signalling. Laposky et al. (2007) suggest that desensitization to leptin could have a genetic component, potentially explaining why some individuals are more prone to obesity and why diets often fail. The brain may not receive the "full" signal effectively, leading to continued eating beyond energy needs.
ANALYSIS OF WHY DIETS FAIL
Counterargument to Taubes: The study presents evidence that low-calorie diets can be successful, challenging Taubes' assertion that calorie restriction is ineffective.
Taubes' Rebuttal: Taubes suggests these diets inadvertently reduce carb intake, which in turn, contributes to their success.
Study Reliability Concerns: The 12-month follow-up showed substantial weight loss but was marred by a high dropout rate, which raises questions about the study's reliability.
Individual Differences: Taubes highlights that carbohydrate sensitivity varies among individuals, affecting their response to dieting.
Long-term Health Implications: Longitudinal research indicates that weight fluctuation may correlate with increased mortality, suggesting complex health outcomes related to dieting.
Prevention Over Cure: Sorenson advocates for obesity prevention as the optimal strategy.
Deterministic Views on Dieting: Research often paints a bleak, predetermined picture of dieting success, potentially discouraging efforts to change.
The Role of Cognition: Other theories, like the Boundary model, emphasize the significant influence of cognitions and psychological factors on dieting outcomes.
Evolutionary Food Preferences: Our evolved preferences for fats and sugars complicate modern dieting efforts due to their abundant availability.
Psychology and Diet Research Challenges: Studies, including reality TV-based ones, face issues like demand characteristics and selection biases, affecting their validity.
Cultural and Social Challenges: Diets requiring drastic changes, like carb elimination, are difficult to adhere to due to societal norms and meal patterns.
Gender Bias in Diet Research: Most diet studies focus on females, limiting generalizability across genders.
Self-report Limitations: Research reliance on self-reported data introduces biases, as admitting to diet failures is socially stigmatized.
Ethical Concerns in Diet Research: Designing restrictive or unbalanced diets for research poses ethical and health risks.
SUCCESSFUL DIETING STRATEGIES
Successful dieting and sustained weight loss require a multifaceted approach beyond simple calorie counting or restrictive eating. Understanding the interplay between dietary habits, psychological factors, social support, and physical activity is essential for a successful weight management plan. Here are some key strategies that contribute to successful dieting:
Fundamental Changes in Eating Habits
Lasting weight loss necessitates a fundamental shift in eating patterns rather than temporary self-starvation. This includes reducing intake of fats and simple carbohydrates while increasing consumption of foods with low caloric density, such as vegetables and fruits, and complex carbohydrates. While some popular diets, like Dr Atkins' plan, recommend high-fat, high-protein, and low-carbohydrate intake, the effectiveness of such diets varies and often lacks extensive testing.
The Role of Social Support
Social support plays a critical role in maintaining motivation and interest in dieting, which is why slimming clubs and tracking progress, as seen in the Truby study, can be highly effective. However, it's important to note that social settings can also influence eating behaviors, as more people can lead to increased food consumption.
Importance of Exercise
Combining diet with regular exercise is crucial for long-term success. Exercise not only aids in burning calories but also increases the basal metabolic rate, enhancing weight loss efforts.
Other Factors Contributing to Success
Eating Slowly: This allows the body to recognize satiety signals, reducing overall food intake.
Healthy Eating Programs: Replacing strict diets with programs encouraging healthy eating habits can prevent negative attitudes toward food.
Monitoring Food Intake: Keeping a detailed record of food consumption helps accurately assess and manage dietary intake.
Avoiding Crash Diets: Sustainable changes in eating habits are more effective and healthier than temporary crash diets.
Eating Behaviors and Psychological Factors
Eating Slowly: This practice allows the brain adequate time to receive signals of satiety from the stomach, reducing the likelihood of overeating.
Attention to Food: Being mindful of what and how much is eaten helps prevent the monotony that can make diets hard to maintain. Focusing on meal details can enhance the eating experience and satisfaction derived from food, reducing the urge for unnecessary snacking.
Specific Conditions for Eating: Establishing particular conditions or settings for eating can help eliminate cues that trigger unnecessary eating, supporting better control over food intake.
Portion Control: Eating smaller portions can help manage calorie intake more effectively, especially when combined with stopping once satisfied, not stuffed.
Sensitivity to Internal vs. External Cues: Some individuals may need to pay more attention to their hunger and fullness cues rather than external factors, like the sight or smell of food, which can lead to overeating.
Physical and Biological Considerations
Incorporating Exercise: Exercise is crucial for burning calories and increasing metabolic rate, both of which are essential for weight loss and maintenance.
Understanding Metabolic Changes: Dieting can lead to decreased metabolism, making it progressively harder to lose weight with each attempt. Awareness of this can help in strategizing diets to minimize such impacts.
Medical Interventions: In cases of severe obesity, bariatric surgery or weight loss medications may be considered. These interventions should be seen as last resort and accompanied by lifestyle changes for long-term success.
Challenges with Dieting
The Failure of Crash Diets: Temporary diets lead to temporary results. Sustainable weight loss requires long-term changes in eating habits.
Underestimating Food Intake: Keeping a food diary can help provide an accurate picture of consumption, countering the tendency among overweight individuals to underestimate how much they eat.
Diet Composition: Diets focusing solely on calorie counting without considering the quality of calories, especially those from refined carbohydrates and sugars, often have lower success rates. Plans that reduce hunger by limiting refined carbs and increasing the intake of complex carbs, proteins, and healthy fats may offer better outcomes.
Social and Cultural Factors
Social Eating: The presence of others can influence the amount consumed. Being mindful of this can help in making better food choices in social situations.
Cultural Influences: Cultural norms and the availability of certain types of food can impact dietary habits. Recognizing and adjusting for these influences can help one stick to a healthy eating plan.
Challenges and Considerations
Despite these strategies, it's important to acknowledge that dieting success varies among individuals, and what works for one person may not work for another. The psychological aspect of dieting, particularly the struggle against cravings for refined carbohydrates and sugars, plays a significant role in the overall success of weight management efforts. Diets focusing on reducing hunger by avoiding refined carbohydrates and sugars may offer a more sustainable approach to weight loss.
EVALUATION
The Spiral Model and the Ironic Process Theory highlight important psychological factors contributing to the difficulty of sustained dieting success. However, these theories also raise questions about how some individuals overcome these challenges and achieve their weight loss goals.
Contributions and Limitations:
The Spiral Model and the Ironic Process Theory illuminate the common pitfalls of dieting, emphasizing the role of psychological and emotional factors in dieting outcomes. They suggest that interventions focusing solely on food restriction without addressing underlying psychological issues may be doomed to fail.
Research supporting these theories, such as the studies by Adriaanse et al. and Heatherton and Polivy, underscores the complex relationship between dieting intentions and behaviours. However, these models do not fully account for the diversity of dieting experiences or explain why some individuals succeed despite the challenges outlined.
The concept of locus of control offers a potential explanation for individual differences in dieting success. It suggests that those with an internal locus of control, who see their weight loss efforts as under their control, may be more likely to achieve lasting success.
