But whether or not weight loss in otherwise healthy people living with obesity is associated with any such benefits remains unknown.
This question in now addressed by Sarah Jackson and colleagues from the UK in a paper published in PLOS | ONE.
The researchers examine data from 1,979 overweight and obese adults, free of long-standing illness or clinical depression at baseline, from the English Longitudinal Study of Ageing.
Participants were grouped according to four-year weight change into those losing ≥5% weight, those gaining ≥5%, and those whose weight was stable within 5%.
The proportion of participants with depressed mood increased by almost 300% in the group that lost weight (about 15% of participants) compared to a rather modest 85% and 62% increase in mood problems in the than weight stable or weight gain groups, respectively.
Compared to the weight stable group, the weight loss group was almost 2 times as likely to report mood problems.
Similarly, individuals in the weight loss group were also more likely to report lower wellbeing.
All effects persisted in analyses controlling for demographic variables, weight loss intention, and baseline characteristics and despite adjusting for illness and life stress during the weight loss period.
Given the longitudinal nature of this study, it is impossible to determine causal relationships in these observations but the findings do suggest that the issue of psychological harm in otherwise healthy individuals undergoing weight loss may warrant closer study.
For the event that there is indeed a causal relationship between weight loss and adverse pychological outcomes, the authors have the following explanation to offer:
“The poor long-term maintenance of weight loss is notorious, and in itself could be interpreted as demonstrating that the personal costs of losing weight exceed the benefits. Resisting food in environments that offer abundant eating opportunities requires sustained self-control, and given that self-control appears to be a limited resource, other areas of life may suffer as a consequence. Loss of fat stores may also initiate signals for replenishment of adipocytes, thereby stimulating hunger and appetite and making weight control progressively more difficult. These observations suggest that weight loss is a significant psychobiological challenge, and as such, could affect psychological wellbeing.”
On the other hand, weight loss could also result from adverse changes in mood:
“Evidence from the clinical literature is suggestive of a causal relationship in this direction, with major depressive disorder often associated with significant weight loss, and treatment with antidepressant medication leading to weight gain. Population studies have also demonstrated longitudinal associations between depressive symptoms and weight loss. Depressed mood may cause weight loss directly or indirectly through changes in appetite or level of physical activity.”
Thirdly, these correlational findings may be entirely unrelated to each other.
Which ever the true relationship, these findings should perhaps caution us against simply advising all overweight or obese people, irrespective of whether or not they actually have weight-related health issues (or are otherwise unhappy with their weight), to try losing some weight.
Jackson SE, Steptoe A, Beeken RJ, Kivimaki M, & Wardle J (2014). Psychological Changes following Weight Loss in Overweight and Obese Adults: A Prospective Cohort Study. PloS one, 9 (8) PMID: 25098417