Because of the limitations of the study, it can't be concluded that tight underwear causes infertility.
But if you're trying for a baby, it can't hurt to try switching to boxers.
Other ways men can increase their chances of conceiving include moderating their alcohol consumption, stopping smoking, exercising regularly, and having a healthy, balanced diet.
This study alone doesn't explain the potential role of irisin.
The research did find that restoring irisin in Alzheimer's mice, including by daily swimming, can boost memory and nerve connections.
But we don't know that the same effects would be seen if people with Alzheimer's were given an exercise programme, for example.
We also don't know if any attempt to increase irisin levels through drug-based treatments (as some in the UK media suggested) would be either effective or safe, as no studies have been carried out in people at this stage.
Obese people who were metabolically healthy – the "fat but fit" – had a 28% higher heart disease risk than their normal weight, metabolically healthy counterparts.
There is no evidence that people exposed to the viral genetic material went on to develop an infection. That said, the researchers' suggestion that people should be encouraged to use alcohol hand disinfectant before and after security checks, to minimise the risk of infection, is sensible advice.
However the connections between diet, lifestyle and cancer outcomes are complex, and while the researchers attempted to adjust their results for other factors, we cannot say with certainty that energy dense foods increase your cancer risk.
The analysis was limited to postmenopausal women and did not consider drink intake, such as sugary drinks and alcohol, which can also be high in calories.
This large study demonstrates that differences between men and women in the quantity and distribution of body fat not only lead to differences in body shape between women and men, but also may have implications for the risk of having a heart attack in later life.
But there are limitations.
Open access. Letter. Imo conducted a systematic literature review of research on the prevalence of burnout among UK medical doctors, arriving at the conclusion that the prevalence of burnout in this population is ‘worryingly high’. Problematically, it turns out that such a conclusion cannot be drawn in view of the state of burnout research. Indeed, there are no clinically valid, commonly shared diagnostic criteria for burnout.2,3
What the research actually shows is that many people from both urban and rural populations in the UK were poor, had little food and were likely to be malnourished. Many relied on white bread, potatoes and some vegetables, with a little meat or milk if they could get it.
There's no new evidence that these people were healthier than the average UK citizen living tody.