@Jdeanda - My wife was initially misdiagnosed as to the source disease. It was a year and half later that she found herself at Johns Hopkins to get another opinion. The doctor asked about her symptoms. One of the things I commented on was the fact that she had lost a considerable amount of weight... that the rate of loss was increasing... and that she was then losing it at a rate of about 10 pounds per month. I additionally commented on the fact that should could not lay flat as it was difficult to sleep. After we shared the whole of her current symptoms and progression, he said...
"We're going to rerun any and all tests that you might already have been given. We might even do some testing that you've not yet had. But given what you described, I believe that we'll find that you have ALS. Even before we get those test results back, I want to get you started on a BiPAP machine to help you with your breathing. One of the problems with those afflicted with ALS is that the lungs are not as good at doing what they are designed to do. Your diaphragm is no longer able to expel the accumulated CO2 that results from the breathing process. As a consequence, and especially at night when you are laying more flat, your body is working especially hard to try to push out that carbon dioxide. In essence, it is like you're running a marathon in your sleep because you are working so hard to breathe correctly. And that is likely why you are losing weight as you have."
Several days later, Darcey received her BiPAP and immediately began to use it at night. She found that she slept more peacefully, dreamed more fully and woke more rested than she had in ages. And in time, we noted that the severe weight loss had abated. Where she would often need multiple daily naps... or even fall asleep in the middle of a conversation... she now found that she was alert and energized until bedtime began to approach. It was a very marked change.
I don't know that this is your Dad's issue with weight loss, but I wanted to share our experience so you could compare. I know that it is a difficult journey to watch your Dad's decline and the feeling of helplessness that can accompany the fact that there seems to be little that you can do. Let me tell you, though... your being there and your determination to make him as comfortable as possible goes a long, long way.
[An aside... Darcey also refused to get a SmartPhone.
Also, early on, her progression seemed rapid... so steadily declining that her neurologist alerted her to the fact that he believed she was within 6 months of life's end. That was March of 2015. She stayed with us until October of 2020. We really don't know what each tomorrow will bring... so live each day and make it as good as it can be!]
My best to you...
Jim