Body size estimation in obesity: a systematic review and meta-analysis

Behavioural evidence of altered sensory attenuation in obesity

“…Thus, it is reasonable to hypothesise some alteration at the higher (i.e., cognitive) level of processing; specifically, we would suggest that the alteration of the sense of agency in obesity may be explained at the light of the tight link between sense of agency and body ownership, which both jointly contribute to a coherent representation of the bodily self (Kilteni & Ehrsson, 2017; Pyasik et al, 2021; Tsakiris et al, 2007). In this vein, the results from the present experiment, suggesting the alteration of the sense of agency in obesity, may be read in conjunction with previous, even though rare, evidence about the characteristics of body ownership in this clinical condition (Scarpina et al, 2019; Tagini et al, 2020a; Tagini et al, 2021b). Nevertheless, to have conclusive remarks, both components should be investigated in the same sample.…”

“…Scarce and not conclusive evidence addressing body ownership had been reported (Scarpina et al, 2019b; Tagini et al, 2020a, 2021a,b) in obesity. A recent work by Tagini and colleagues (2020a) compared the susceptibility of individuals affected by obesity to the well-known Rubber Hand Illusion (Botvinick & Cohen, 1998, that is, an experimental procedure leading individuals to feel as if a rubber hand was part of their own body) with a sample of healthy-weight individuals.…”

Does physical weight alter the mental representation of the body? Evidence from motor imagery in obesity

“…Although the authors did not test the explicit judgement, they hypothesise a role of awareness in accessing body representation to explain an altered body estimation in obesity according to Longo (2015). This hypothesis grounds on some previous evidence according to which individuals with obesity are generally less accurate in comparison with healthy-weight individuals in estimating the physical dimension of specific body parts, such as the abdomen or the shoulders (Scarpina et al, 2014; Schwartz & Brownell, 2004; Tagini, Scarpina, & Zampini, 2021). Following such a hypothesis, we might expect that any impact we had found of obesity on motor imagery would be more related would be more related to levels of awareness prompted by the task.…”

“…Previous literature, which focused largely on size estimation, is heterogeneous in terms of results on the whole body versus body parts. Individuals with obesity overestimate, underestimate, or are accurate in estimating whole body-size dimensions, although they are generally less accurate or show a comparable performance to healthy-weight individuals when they estimate the physical dimension of specific body parts (Schwartz & Brownell, 2004; Tagini, Scarpina, & Zampini, 2021). Our results seem to point towards a similar effect in individuals with obesity and healthy-weight individuals when body part actions are considered.…”

“…While in Scarpina and colleagues (2017) participants were induced to think they were performing a memory task, and hence relying on a more implicit motor imagery strategy to perform actions, in Guardia and colleagues (2013) the participant explicitly imagined to perform the movement before the real action. Interestingly, the role of strategy in obesity is evident in other tasks involving the body, but not actions: as reported in a recent review (Tagini, Scarpina, & Zampini, 2021), affected individuals traditionally show an altered mental representation of their own physical dimensions when they are explicitly asked to judge them (i.e., Scarpina et al, 2014, 2017; Schwartz & Brownell, 2004); however, they describe the same features accurately when the processes are implicit (as in Tagini, Scarpina, Scacchi, et al, 2021). It is worth to note that both Guardia and colleagues (2013) and Scarpina and colleagues (2017) tested an obstacle-avoidance action, a walking through door-like openings).…”