Diet failure is not a matter of insufficient willpower or poor food choices alone. Despite an ever-growing number of diet plans, obesity and metabolic disorders remain on the rise globally. A 2020 review published in the BMJ highlighted that most weight-loss interventions fail to produce sustained weight loss beyond 12 months, with many individuals regaining the weight lost or even exceeding their starting weight (MacLean et al., 2015). The reasons behind this failure lie not in the food itself, but in the underlying psychological and behavioural mechanisms that govern our relationship with eating. Understanding these mechanisms is essential if we are to break the cycle of yo-yo dieting and achieve long-term health.
The Role of Diet Mentality
The concept of “diet mentality” refers to a rigid mindset where eating is governed by external rules rather than internal cues. This often includes categorising foods as “good” or “bad,” obsessively counting calories, and feeling guilt or shame after eating. Research has shown that this approach can lead to binge eating, emotional eating, and disordered eating patterns. A seminal study by Polivy and Herman (1985) found that restrained eaters—those who try to restrict their food intake—are more likely to overeat in response to stress, emotional triggers, or even after breaking their diet slightly.
The Psychology of Restriction
Restrictive diets activate a psychological backlash known as the “what-the-hell effect,” described by Herman and Mack (1975). When an individual violates a self-imposed food rule (e.g. eating a “forbidden” food), they are likely to abandon all restraint and overeat. This phenomenon is not a failure of discipline, but a predictable response to a mindset that frames dietary lapses as moral failings. In contrast, individuals with more flexible approaches to eating exhibit better long-term outcomes in both weight maintenance and mental health (Westenhoefer, 1991).
Habits Over Willpower
Willpower is a finite resource, and relying on it to control food intake is unsustainable over time. Research by Baumeister et al. (1998) on ego depletion shows that self-control operates like a muscle that becomes fatigued with overuse. Habit formation, not willpower, is the key to long-term behaviour change. According to a study by Lally et al. (2010), it takes an average of 66 days for a new habit to become automatic. By focusing on building consistent, healthy habits rather than adhering to rigid diet rules, individuals are more likely to achieve sustainable change.
Emotional Eating and Coping Mechanisms
Food is often used as a coping mechanism to deal with negative emotions such as stress, boredom, loneliness, or sadness. This is particularly prevalent in individuals who diet frequently. A study by Macht and Simons (2011) showed that dieting increases emotional reactivity to food cues, making individuals more susceptible to emotional eating. Addressing the emotional drivers of eating is crucial. Techniques such as mindfulness, cognitive behavioural therapy (CBT), and stress management strategies have been shown to reduce emotional eating and improve overall dietary behaviours (Forman et al., 2007).
The Role of Self-Compassion
Self-compassion has emerged as a powerful predictor of healthy eating behaviour. Rather than harsh self-criticism, individuals who practice self-compassion respond to dietary lapses with understanding and support, which reduces the likelihood of relapse. Adams and Leary (2007) found that participants who were instructed to be self-compassionate after eating a forbidden food consumed significantly fewer calories in a subsequent taste test than those who were self-critical. Self-compassion also correlates with lower levels of disordered eating and greater body satisfaction (Kelly et al., 2014).
The Problem with Short-Term Goals
Most diets focus on short-term results such as rapid weight loss, which can backfire in the long term. Rapid weight loss often involves muscle loss and metabolic slowdown, both of which make weight maintenance more difficult. A meta-analysis by Mann et al. (2007) concluded that long-term weight loss from dieting is rare, and that dieting predicts future weight gain more than it predicts weight loss. Setting intrinsic, process-oriented goals—like eating more vegetables or exercising regularly—has been shown to produce better long-term health outcomes (Teixeira et al., 2012).
The Importance of Internal Cues
Humans are born with the ability to regulate their food intake based on hunger and satiety. However, chronic dieting disrupts these internal cues. Intuitive eating is an evidence-based approach that encourages individuals to reconnect with these signals. Tylka and Kroon Van Diest (2013) found that intuitive eating is associated with lower BMI, better psychological health, and reduced incidence of disordered eating. Unlike dieting, intuitive eating fosters a sustainable relationship with food by focusing on body awareness rather than external rules.
The Social and Cultural Environment
Our food choices are heavily influenced by social and cultural factors. From childhood messaging to peer pressure and media portrayal of ideal bodies, societal norms can distort our relationship with food. A study by Christakis and Fowler (2007) showed that obesity can spread through social networks, highlighting how social norms affect behaviour. Addressing mindset involves critically evaluating these influences and consciously choosing to adopt health-promoting behaviours that align with personal values rather than external expectations.
Identity and Self-Image
One often-overlooked factor in diet failure is self-identity. If a person sees themselves as someone who “always struggles with food” or is “not disciplined,” their behaviours will often reflect that belief. This is in line with identity theory, which suggests that people act in accordance with their self-concept (Burke & Stets, 2009). Shifting from a dieter identity to one of a healthy, mindful eater can drive more sustainable change. Self-affirmation techniques and visualisation have been shown to support this identity shift (Logel & Cohen, 2012).
Behavioural Consistency and Environmental Design
The environment we inhabit plays a major role in shaping our habits. Rather than relying on motivation, altering the physical and social environment to support healthy behaviours can lead to automatic, consistent action. A study by Wansink (2004) demonstrated how simple changes, like using smaller plates or keeping unhealthy snacks out of sight, significantly reduce calorie intake. Creating a supportive environment increases the chances of success by reducing reliance on conscious decision-making.
Sleep, Stress and Physiology
Physiological factors also play a role in diet failure. Chronic stress elevates cortisol levels, which is associated with increased appetite and fat storage (Epel et al., 2000). Similarly, sleep deprivation disrupts hunger hormones like ghrelin and leptin, leading to increased hunger and cravings (Spiegel et al., 2004). Improving sleep hygiene and managing stress are often overlooked yet critical components of a sustainable eating strategy.
Bibliography
Adams, C.E. and Leary, M.R., 2007. Promoting self–compassionate attitudes toward eating among restrictive and guilty eaters. Journal of Social and Clinical Psychology, 26(10), pp.1120–1144.
Baumeister, R.F., Bratslavsky, E., Muraven, M. and Tice, D.M., 1998. Ego depletion: is the active self a limited resource? Journal of personality and social psychology, 74(5), p.1252.
Burke, P.J. and Stets, J.E., 2009. Identity theory. Oxford University Press.
Christakis, N.A. and Fowler, J.H., 2007. The spread of obesity in a large social network over 32 years. New England journal of medicine, 357(4), pp.370–379.
Epel, E., Lapidus, R., McEwen, B. and Brownell, K., 2000. Stress may add bite to appetite in women: a laboratory study of stress-induced cortisol and eating behavior. Psychoneuroendocrinology, 26(1), pp.37–49.
Forman, E.M., Hoffman, K.L., McGrath, K.B., Herbert, J.D. and Brandsma, L.L., 2007. A comparison of acceptance-and control-based strategies for coping with food cravings: An analog study. Behaviour Research and Therapy, 45(10), pp.2372–2386.
Kelly, A.C., Vimalakanthan, K. and Miller, K.E., 2014. Self-compassion moderates the relationship between body dissatisfaction and disordered eating. Eating Behaviors, 15(3), pp.453–458.
Lally, P., Van Jaarsveld, C.H., Potts, H.W. and Wardle, J., 2010. How are habits formed: Modelling habit formation in the real world. European journal of social psychology, 40(6), pp.998–1009.
Logel, C. and Cohen, G.L., 2012. The role of the self in physical health: Testing the effect of a values-affirmation intervention on weight loss. Psychological Science, 23(1), pp.53–55.
MacLean, P.S., Wing, R.R., Davidson, T., Epstein, L., Goodpaster, B., Hall, K., Levin, B.E., Perri, M.G., Rolls, B.J., Rosenbaum, M. and Seeley, R.J., 2015. NIH working group report: Innovative research to improve maintenance of weight loss. Obesity, 23(1), pp.7–15.
Macht, M. and Simons, G., 2011. Emotional eating. In Frontiers in Eating and Weight Regulation (pp. 103–120). Karger Publishers.
Mann, T., Tomiyama, A.J., Westling, E., Lew, A.M., Samuels, B. and Chatman, J., 2007. Medicare’s search for effective obesity treatments: Diets are not the answer. American Psychologist, 62(3), p.220.
Polivy, J. and Herman, C.P., 1985. Dieting and binging: A causal analysis. American psychologist, 40(2), p.193.
Spiegel, K., Tasali, E., Penev, P. and Van Cauter, E., 2004. Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Annals of internal medicine, 141(11), pp.846–850.
Teixeira, P.J., Carraca, E.V., Markland, D., Silva, M.N. and Ryan, R.M., 2012. Exercise, physical activity, and self-determination theory: A systematic review. International Journal of Behavioral Nutrition and Physical Activity, 9(1), p.78.
Tylka, T.L. and Kroon Van Diest, A.M., 2013. The Intuitive Eating Scale–2: Item refinement and psychometric evaluation with college women and men. Journal of Counseling Psychology, 60(1), p.137.
Wansink, B., 2004. Environmental factors that increase the food intake and consumption volume of unknowing consumers. Annual review of nutrition, 24, pp.455–479.
Westenhoefer, J., 1991. Dietary restraint and disinhibition: Is restraint a homogeneous construct? Appetite, 16(1), pp.45–55.
Herman, C.P. and Mack, D., 1975. Restrained and unrestrained eating. Journal of personality, 43(4), pp.647–660.
