Skimping on sleep can derail your metabolism. In a study at the University of Chicago, people who got four hours of sleep or less a night had more difficulty processing carbohydrates. "When you're exhausted, your body lacks the energy to do its normal day-to-day functions, which include burning calories, so your metabolism is automatically lowered," explains Peeke.
It isn’t so much the metabolism slowing in my 50’s as it is the bad habits associated with youth. A box of Mac and Cheese was not a bad choice when competitive and highly active, I needed the carbs. But the mindset that a full box is a single sized serving remains despite the slow down in activity and metabolism. That’s where the real challenge lies. Too many years of eating rabbit food only after it was processed into a rabbit (or steer preferrably) with potato or corn as the only acceptable vegetable.