Hi Bob,
The answer to you question is yes, our digestive system changes as we get older. It gets less efficient and slows down. Peristalsis becomes weaker and slower and we experience a decrease in enzyme and acid production. Our bowel muscles tend to get weaker as well, and our gut biome changes by becoming less diverse in the number of good (and bad) bacteria that reside there. This can decrease our immune system function which can lead to a higher susceptibility to 'not good' things. Hey.......you asked!
Back to you. You're going about it the right way........by asking what's changed. Ensure is not an ostomate's friend. Whenever you see something with more grams of sugar than protein........it's essentially a candy bar, whether liquid or solid. When we consume sugary drinks it causes our body to secrete water into our bowels to try to dilute the sugary liquid into something the body can use. That water is then reabsorbed later by your colon........assuming you have one. If not it just tends to flush the body out more than help it. Liquids in general are a problem for most ostomates, unless their terminal ileum and full colon are still intact, so if the Ensure is the only change you've made to your diet then try getting more protein from solid forms of food and leave the sugar in the Ensure container. Interesting point that most don't know is that there's nowhere in the digestive tract where pure water can be absorbed. It has to be in combination with a co-transporter like sodium and glucose. Even the colon can’t absorb pure water. Just your fun fact for today.
Also, as you age your muscles naturally atrophy. The saying "if you don't use it you'll lost it" definitely applies to muscle mass as we get older. So with less muscle mass to provide for.......the appetite can decrease as well. You didn't say yours did, but just something to be mindful of for the future. Assuming you're eating the same and maintaining the same activity level and the only thing that's changed is the Ensure.......I'd start there. You also didn't mention how much weight you've lost.......are we talking 5 lbs, 10 lbs or more? Of course WHEN you eat and drink is as important as what you eat, and the order in which you eat your proteins, fats and carbs matters too......but I'm assuming that hasn't changed.
As an aside........the best doctor I've ever had was a PA-C. She was amazing, but had to move out of state for family reasons. I haven't found anyone yet that could touch her, no matter how many degrees they had hanging on the wall in their waiting room. Just saying.......you never know.
;O)