Overweight, obesity appear to lower risk of acne development in youths
Overweight and obesity show an inverse relationship with acne in a dose-dependent manner in young adults, according to a recent study. This suggests that the metabolically active adipose tissue plays a protective role in acne.
A total of 301,241 females (50.1 percent; mean age 18.7 years) and 299,163 males (49.9 percent; mean age, 18.9 years) were recruited, among whom 48,969 (16.3 percent) and 55,842 (18.7 percent) were diagnosed with acne, respectively.
A gradual decrease was noted in the proportion of participants with acne from the underweight to the severely obese group (males: from 19.9 percent to 13.9 percent; females: from 16.9 percent to 11.3 percent). [J Am Acad Dermatol 2019;81:723-729]
Multivariable analysis had results similar to those on unadjusted analysis, which revealed the lowest risks of acne development in severely obese participants (adjusted odds ratio [aOR] for males, 0.53, 95 percent CI, 0.42–0.64; aOR for females, 0.5, 0.37–0.62). These results persisted in sensitivity analyses.
“Owing to the cross-sectional study design, we could not infer a causal relationship between body mass index (BMI) and acne,” the researchers said. “It is possible that the protective effect of excessive BMI against acne is attributed to the increase in aromatase activity and peripheral conversion of androgens to oestrogens induced by excessive adipose tissue.” [Med Hypotheses 1999;52:49-51]
Oestrogens have been shown to reduce sebum production and to counter the effects of androgens on the sebaceous glans, which contributes to its protective benefit against acne. [Arch Dermatol 1973;108:210-214; Horm Metab Res 2007;39: 85-95]
Moreover, obesity and intra-abdominal fat were negatively associated with total testosterone concentration and positively associated with oestradiol level. There were also studies reporting that obesity suppressed the activity of 5-α reductase-II, which converts testosterone to the more physiologically active dihydrotestosterone. [Metabolism 1990;39:897-901; J Clin Endocrinol Metab 1993;76:1140-1146; J Endocrinol 2006;191:637-649; J Urol 2015;194:1031-1037]
“In contrast, other mechanisms were suggested to promote acne by adipose tissue such as adipokine-driven inflammation,” the researchers said. “Although the net outcome of these contrasting effects has yet to be determined, our findings suggest that there is an inclination toward a protective effect of adiposity.” [Indian J Dermatol Venereol Leprol 2013;79:291-299]
A reverse causality should also be considered due to the unavailability of data on the exact time of acne onset and the duration of obesity, they added. Of note, weight gain has been shown to be a side effect of oral contraceptives, so it is possible that the reduced rates of acne among overweight and obese females might be partially attributable to treatment of acne with oral contraceptives. [Am J Prev Med 2016;51:e165-e178]
The current nationwide, population-based, cross-sectional study was conducted from 2002 to 2015 using medical data on 600,404 youths during compulsory military service. BMI of participants was measured at age 17 years. The researchers calculated unadjusted and adjusted ORs of acne in association with BMI (stratified into eight groups), with the low-normal group as reference.
“Further studies including important variables in the obesity-acne relationship are needed to validate our findings,” the researchers said.