“I’m not overweight and I run a lot, so I am not at risk of diet-induced metabolic disorder because I balance my calories with activity.”
This is incorrect. Obesity is a marker for metabolic dysfunction, not the end result.
In fact being “Skinny-fat” can be more dangerous than carrying extra pounds. What is skinny-fat? In short- not enough meat on the bone.
You must maintain muscle volume to carry out basal metabolic function. You know how your doctor looks at your cholesterol and says, “Well, your ‘bad’ cholesterol isn’t high but your ‘good’ cholesterol is still too low,” and you say, “But if ‘good’ cholesterol is for removing ‘bad’ cholesterol which I don’t have, why do I need more?” And the Dr. says “Just shut up and fix it! I’m a doctor, not a professor!” Skeletal muscle is a similar circumstance.
If you are an adult, if you’re not gaining muscle, you’re probably losing it. And you don’t gain (significant) muscle mass with Yoga or being a cardiobunny. The human animal needs to live in a way that increases muscle mass. Do not fear “bulking up” and in turn lose your ability to thrive as a normal human.
Secondarily, research shows that thin people with non-alcoholic fatty liver disease have a risk of death twice as high as obese people. We now know that excess fructose sugar (1/2 of sucrose-of which the average American eats 25-30 lbs./ year) causes the same chronic damage to the liver that alcohol does. This is called non-alcoholic fatty liver disease (NAFLD) or N.A.S.H.-Nonalcoholic steatohepatitis and you can suffer this while skinny as a rail. Throw in hepatic dyslipidemia (fatty liver disease) and you have yourself a fatal party and your pants still fit.