Is it possible to increase metabolism as you get older?

I tried to lose weight and live a healthier lifestyle last year and I thought I lost the weight through just the lifestyle changes and exercise but earlier this year I lost proprioception on the left side of my body and since then I've had to increase my calorie intake 4x to maintain my weight.

Listening back to some recordings my voice also deepened in the past 3 months.

The past two days I've eaten egg whites and bacon for breakfast, grilled chicken salad, and an entire pizza for dinner. Mix in icecream and about half a dozen candy bars and I haven't gained a pound.

I ask because despite all this increased eating I haven't had a BM since Thursday and I feel fine.

I saw a neurologist to check for MS and or ALS (because of the lack of proprioception and loss of muscle tone) and I'm worried that all my eating is just masking any weight loss. When I say loss I mean I averaged 1-2 lbs a day since 1/3 until 1/16. 1/16 was the last BM I remember.

Before 1/3 I would diet using low carb / high protein and exercise. I wouldn't normally have a BM while dieting which is why I would eat normally on the weekends and at night. Even with exercise I would have a healthy BM.

Now I eat, eat, eat and didn't exercise during this period but no BM.