One of the interesting epidemiological findings in virtually every population study, is that the prevalence of overweight and obesity in men and women, with a few minor differences in age distribution, is virtually identical.
Yet, both commercial and non-commercial weight loss programs as well as bariatric centres are overwhelmingly frequented by women.
Interestingly, research studies on weight loss and obesity management are also almost exclusively done in women.
This, not surprising, but important fact, is elegantly demonstrated in a paper by Sherry Pagoto and colleagues from the University of Massachusetts, published in the latest issue of OBESITY, which examined the inclusion of men in randomised controlled trials of lifestyle weight loss interventions.
Their analysis of 244 studies with a total of 95,207 participants published in the last 10 years (1999-2009), revealed on average 27% male vs. 73% female participants.
Interestingly, trials recruiting a diseased sample included a larger proportion of males than those not targeting a disease (35% vs. 21%).
About 32% of trials used exclusively female samples, whereas only 5% used exclusively male samples .
No studies in the past 10 years specifically targeted minority males as a result of which ethnic males composed 1.8% of total participants in US studies.
Only 24% of studies that underrepresented males provided a reason for doing so.
This of course has major clinical implications, as it means that very little is known about the efficacy or effectiveness of lifestyle interventions in men and virtually nothing is known about weight management in non-white men.
Based on these data, evidence-based lifestyle management of obesity in men is virtually impossible and appears to be a major knowledge gap.
While I appreciate the many reasons why women are so much more likely to participate in weight loss studies and seek out obesity treatments, the fact remains that for men seeking (and perhaps requiring) such treatments, there is virtually no knowledge base on which to make any kind of recommendations.
This gender discrepancy that is perhaps unique for a non-gender related health problem (remember obesity is as common in men as in women), is something that may have to be addressed in future funding-policy decisions.
Currently, there are ‘affirmative action’ type rules in place to ensure fair representation of women in clinical trials – in fact the Canadian Institutes of Health Research has a whole institute dedicated to addressing the issue of gender and health and it appears that much of its activities appear dedicated to studying issues of particular significance for womens’ health.
This discrepancy in gender distribution in obesity research may be a reason to prompt specific initiatives by this and other institutes to ensure that future studies on obesity management (be it lifestyle or other interventions) include a proportion of men that equitably represents the prevalence of excess weight and the burden of obesity in the male population.
Pagoto SL, Schneider KL, Oleski JL, Luciani JM, Bodenlos JS, & Whited MC (2011). Male Inclusion in Randomized Controlled Trials of Lifestyle Weight Loss Interventions. Obesity (Silver Spring, Md.) PMID: 21633403