Just a few flaws I discovered quickly:
Respondents classified themselves as either "players" or "non-players," and also provided "self-assessments of depression, personality, health status, physical and mental health, body mass index (BMI), and poor quality of life."
It's self-assessed, that means that their opinion is affected by their current mood, level of awareness, energy, and current situation.
If you asked me on my mental well-being after spending time with a group of friends having a laugh then it would be considerably different than the day when I feel depressed because things are not how I want them to be.
while males reported higher body mass index
Health-risk factors, specifically, a higher BMI
BMI means very little. Body fat percentage is what matters for healthiness.
I have a friend who is a couple of inches taller than me but almost twice the weight. Is he fat? No, he spends 5 days a week in the gym and goes through an insane amount of protein a day.
You measure a Rugby/American Football players BMI and he will be told he is overweight as BMI does not account for muscle.