Why diets fail: Obesity and mental health

Issue: BCMJ, vol. 60, No. 10, December 2018, Pages 506-507 Council on Health Promotion

Simplistic approaches to the treatment of obesity focusing on restrictive diets or increased exercise power the lucrative weight-loss industry and provide endless hours of reality television, but provide clinicians with no useful models to help those who struggle with serious obesity. While research has shown almost every popular diet to assist in weight loss, there is no diet that seems to help more than a small fraction of participants beyond a couple of years. Further, most gain back the weight they lost. It seems that no matter how well a diet works early on, long-term adherence to popular diets tends to be dismal.

Research is helping us understand why we should consider a more thoughtful and empathic approach to obesity. As we grow up, our normal weight is adjusted upward and food intake is hormonally regulated to ensure that it is sufficient to support growth. If we gain excessive weight, what our body considers our normal weight continues to increase.[1] After intentional weight loss, potent neuroendocrine physiology defends our previous maximum weight and our food intake eventually increases until we regain most or all of the weight lost. This physiological pressure to regain lost weight is persistent and likely permanent. Bariatric surgery impacts the hormones regulating this set point. Anti-obesity pharmaceuticals also target these systems, with less impressive outcomes. Although these interventions have their place, to treat obesity successfully, we need to consider addressing modifiable contributors to weight gain, and assist patients with barriers to successful lifestyle modification.

The complex and inseparable relationship between obesity and mental health is one reason why a simple diet or exercise plan has no lasting value. Childhood trauma, neglect, abuse, food insecurity, and posttraumatic stress disorder often precede lifelong, severe obesity, and pose challenges to treatment.[2,3] Attention deficit hyperactivity disorder (ADHD) is strongly associated with obesity, especially in adults, and coaching those with ADHD to maintain lifestyle modifications is difficult.[4] Depression is a common comorbidity in obesity, and is strongly associated with hyperphagia, anxiety, severe fatigue, and chronic pain, all of which are barriers to effective treatment.[5] Obesity is associated with a high risk of obstructive sleep apnea, which is strongly associated with depression, severe sleepiness, fatigue, cognitive impairment, and increased appetite promoting hormones.[6] Disorderly eating patterns and comorbid eating disorders (especially binge eating disorder) are common, especially with severe obesity. Simply prescribing a restricted diet or strategies such as fasting may exacerbate disorderly eating patterns.[7] Perhaps the most common problem seen in obesity treatment are patients struggling with chronic stress and anxiety who develop habitual emotional eating behaviors to cope.[8] Prescribing dietary changes without assisting these patients in stress management and treating their anxiety is of little long-term value.

Patients with obesity experience judgment, bigotry, and discrimination in all facets of society, including health care settings.[9] Motivating positive change in patients with low self-esteem and a history of repeated failures to maintain weight loss is best achieved by establishing an accepting, nonjudgmental milieu, and helping them reframe their efforts to change as a lifelong journey rather than a race to achieve a weight-loss goal. By helping patients set realistic behavioral goals and assisting them to identify and address the root causes of their obesity, physicians can empower them to make lifestyle changes that are enjoyable, sustainable, and effective.
—Michael R. Lyon, MD, ABOM


This article is the opinion of the Nutrition Committee, a subcommittee of Doctors of BC’s Council on Health Promotion, and is not necessarily the opinion of Doctors of BC. This article has not been peer reviewed by the BCMJ Editorial Board.


1.    Farias MM, Cuevas AM, Rodriguez F. Set-point theory and obesity. Metab Syndr Relat Disord 2011;9:85-89.

2.    Althoff R, Ametti M, Bertmann F. The role of food insecurity in developmental psychopathology. Prev Med 2016;92:106-109.

3.    Williamson DF, Thompson TJ, Anda RF, et al. Body weight and obesity in adults and self-reported abuse in childhood. Int J Obes Relat Metab Disord 2002;26:1075-1082.

4.    Cortese S, Comencini E, Vincenzi B, et al. Attention-deficit/hyperactivity disorder and impairment in executive functions: A barrier to weight loss in individuals with obesity? BMC Psychiatry 2013;13:286.

5.    Lasserre AM, Glaus J, Vandeleur CL, et al. Depression with atypical features and increase in obesity, body mass index, waist circumference, and fat mass: A prospective, population-based study. JAMA Psychiatry 2014;71:880-888.

6.    Kerner NA, Roose SP. Obstructive sleep apnea is linked to depression and cognitive impairment: Evidence and potential mechanisms. Am J Geriatr Psychiatry 2016;24:496-508.

7.    Urquhart C, Mihalynuk TV. Disordered eating in women: Implications for the obesity epidemic. Can J Diet Pract Res 2011;72:e115-25

8.    Scott C, Johnstone AM. Stress and eating behaviour: Implications for obesity. Obes Facts 2012;5:277-287.

9.    Phelan SM, Burgess DJ, Yeazel MW, et al. Impact of weight bias and stigma on quality of care and outcomes for patients with obesity. Obes Rev 2015;16:319-326.

Michael R. Lyon, MD, ABOM. Why diets fail: Obesity and mental health. BCMJ, Vol. 60, No. 10, December, 2018, Page(s) 506-507 - Council on Health Promotion.

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