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Side Effects of Under Eating

There are various reasons as to why a person may under-eat from participating in trends like dieting culture, excessive stress or being an individual with an eating disorder (Stewar et al., 2022; Wallis & Hetherington, 2009) . Undereating can have adverse effects not only on an individual's health but also a person's well-being. The harmful impact of under-eating often is neglected and cast away in conversations. 

So what does the research suggest about undereating? 

Consistent findings have emerged regarding the negative effects of undereating. Specifically, the Minnesota Starvation Study which utilised young, healthy, psychologically well individuals showcased the drastic negative impact of food restriction on an individual's physical, social, behavioural, and psychological well-being (Baker & Keramidas, 2013). 

Changes to Attitudes and Behavior surrounding Food and Eating & Eating Patterns:

Participants in the Minnesota Starvation Study reported difficulty concentrating on things as thoughts were consumed by food and eating, this is also called food preoccupation. In addition differing eating habits were reported as many struggled to regain control, resulting in binge eating. 

Physical Changes and Impact on Physical Activity:

During the semi-starvation period the  Minnesota Starvation Study revealed many negative effects. From, reduced strength, oedema, hair loss, decreased tolerance of cold temperature, dizziness, headaches, decreased need for sleep and metabolism on the physical body. Furthermore, participants became apathetic and lacked energy echoing other research which has found a lack of calories consumed can impact physical fitness (Ghonch et al., 2013). 

Emotional & Cognitive changes:

Individuals also reported periods of depression, irritability and frequent outbursts of anger. The findings of symptoms of depression are consistent with the literature (Anglin et al., 2013; Golding et al., 2009). The Minnesota Starvation Study also found that participants displayed impaired concentration and alertness. Further research supports the notion of cognitive and emotional changes from changes in the neurochemical systems of the brain such as serotonergic, dopaminergic, and opioidergic areas (Murray et al., 2015).

Social and sexual changes:

Many individuals from the Minnesota Starvation Study also became socially withdrawn and isolated and some men reported a loss of libido. Alternative research has found undereating, and the lack of insufficient calories can impact both men and women's reproductive functioning such as menstrual irregularities or sexual dysfunction (Martin et al., 2009; Dunkely et al., 2019). 

If you think you have been affected by malnutrition and want to seek some support, please contact the Team and we can help:


Anglin, R., Samaan, Z., Walter, S. D., & McDonald, S. D. (2013). Vitamin D deficiency and depression in adults: systematic review and meta-analysis. British Journal of Psychiatry, 202(2), 100–107. 

Baker, D. B., & Keramidas, N. (2013). The psychology of hunger. 

Dunkley, C. R., Gorzalka, B. B., & Brotto, L. A. (2019). Associations between sexual function and Disordered eating among Undergraduate women: An emphasis on sexual pain and distress. Journal of Sex & Marital Therapy, 46(1), 18–34. 

Ghoch, M. E., Soave, F., Calugi, S., & Grave, R. D. (2013). Eating Disorders, Physical Fitness and Sport Performance: A Systematic review. Nutrients, 5(12), 5140–5160. 

Golding, J., Steer, C., Emmett, P. M., Davis, J. M., & Hibbeln, J. R. (2009). High levels of depressive symptoms in pregnancy with low omega-3 fatty acid intake from fish. Epidemiology, 20(4), 598–603.

Keys, A., Brožek, J., Henschel, A., Mickelsen, O., & Taylor, H. L. (1950). The biology of human starvation. (2 Vols.). Univ. of Minnesota Press.

Martin, B., Golden, E., Carlson, O. D., Egan, J. M., Mattson, M. P., & Maudsley, S. (2008). Caloric restriction: Impact upon pituitary function and reproduction. Ageing Research Reviews, 7(3), 209–224. 

Murray, S., Arosenius, A., & Avena, N. M. (2015). Neurochemical Components of Undereating and Overeating. Wiley, 394–407. 

Stewart, T. M., Martin, C. K., & Williamson, D. A. (2022). The Complicated Relationship between Dieting, Dietary Restraint, Caloric Restriction, and Eating Disorders: Is a Shift in Public Health Messaging Warranted? International Journal of Environmental Research and Public Health, 19(1), 491. 

Wallis, D. J., & Hetherington, M. M. (2009). Emotions and eating. Self-reported and experimentally induced changes in food intake under stress. Appetite, 52(2), 355–362. 


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