I am aware of research that shows the unsurprising fact that bariatric surgery (and therefore large weight loss) in men tends to increase testosterone over the long term. But there is also the, again unsurprising fact, that males suffering from AN will often have serious issues with low testosterone. And that dieting itself can cause acute short-term issues (which then go away on resumption of maintenance calories).
So at what level of body fat does weight loss stop being beneficial and begin to lower natural testosterone levels?
There is unlikely to be one specific bodyfat threshold across all individuals where this begins happening, much like how different individuals may experience signs/symptoms of hypogonadism at different levels of “low” testosterone levels – and some don’t experience signs/symptoms at all (in which case, there is no reason to be checking blood levels at all).
Males with anorexia nervosa have a number of other issues that need to be addressed, of course; for the majority of individuals, focusing on our primary guidelines for health is a worthwhile goal without placing excessive importance or worry on blood testosterone levels.
Thank you. I’ve read a couple of the bodybuilder studies (10.1519/JSC.0b013e3181cb6fd3 and 10.1123/ijspp.8.5.582), but the effect they look at there is acute, and likely dominated by diet, since they are not looking at individuals trying to hold a steady state. I hope to lose a few more inches from where I’m at, and I’d like to separate out short term diet-induced mood changes from changes brought about from the low body fat level itself.
Have you guys considered updating your 37" waist recommendation with a WtHR instead? Ie., that waist should be 50% of height. I have a friend who is 6’2" and trying to lose weight, and 37" puts him into the bottom mortality quintile, while for a 5’9" guy like me, that same lowest mortality bucket would be 34-5", and at my current 38" I’m still pretty chubby. A WtHR would also a bit more globally applicable to Asians, Swedes, shorts and talls, etc. Waist circumference sweeps a lot of variation under the rug. (10.1017/S0954422412000054, see Fig 2 for visceral fat content pics)
Not at this time, as the evidence does not show that WHR or WHtR are superior to BMI and WC. The evidence that does show WHR or WHtR can work for predicting risk is not nearly as robust compared to BMI and WC, despite the limitations of these. If the evidence accumulates and subsequent guidelines change, we’ll change our recommendations. At this time however, it wouldn’t be an “update” to use WtHR.
Speaking to your specific example, I’m don’t know that he and you need significantly different screening waist measurements to reduce your risk of adiposity-related disease. 37" seems like a reasonable cut-point given the existing data, which should be coupled with medical history. The study you linked does not show that WHR or WHtR are superior for predicting risk of adiposity-related disease.