1. I have a trainer who likes to use oat bran for "lifting heavy". It seems to work well for her, but I don't see how a carb like that would make someone "muscular".
It absolutely can. If the person is also eating adequate protein, the carb will spike insulin which builds muscle. This is why a body builder's favorite food is meat and potatoes. The protein in the meat alongside the prolonged insulin released, caused by the potatoes action on your blood glucose, behaves like an antigen would on your immune system. It's just a way of achieving a more prolonged insulin release so it acts on muscle mass longer. Of course, this only works if the person has proper insulin function that is actually building muscle rather than fat. You also would have to be quite a heavy trainer.
2. The diet program I am on, has desserts but they aren't recommended for "fat people". I feel like I am being signaled out on not being able to enjoy what the others are eating. Why would a calorie centered program care if I am eating dessert or not if it's within my daily calorie budget?
For the same reason that I have explained before. A lot of calorie centered programs are not fully calorie centered. They try to sneak in macronutrient (macros) composition in order to achieve better outcomes. This is because they are fully aware that a calorie is not a calorie. The calories of different macros are allocated differently in the body.
They most likely want you to stay away from dessert because, even if the dessert is within your calorie allotment, most of those calories are coming from some sort of carb. They want you to avoid the carbs because they know carbs disrupt blood glucose and this will cause further weight gain or the inability to lose weight. Sneaky, sneaky but I know all their tricks.
3. Will a diet program that keeps a calorie target between 1500 - 1800 a good one to follow?
That is very hard to say. I can say that, at least, that's not a ridiculous calorie goal like some other programs have. I am sure you will lose "weight" though. At least, initially. How far you can go and how long your results will last, are another story.
4. I am following a program that is heavy on the artificial sweeteners (AS). Will this interfere with my weight loss goals? Also why are diet programs so loaded with AS?
Because they are loaded with BS.
Most programs are loaded with AS because they know this is what will entice people to continue following the protocol. People like to eat novelties. They are used to it because that's what makes up most of the Standard American Diet's (SAD) fare. Removing these and having to eat real meals is extremely difficult for most. So, junk has to be included in any diet program.
I can't say if it will interfere with your goals or not. You would have to try it and see. What I can say is that chronic consumption of AS effects overweight/obesity in a negative way through hypothalamic dysfunction. So, if you want to have a greater chance of meeting your goals, you will want to eliminate AS from the diet.
5. I am helping people to lose weight and recommend eating protein to prevent sarcopenia, but a lot of my clients seem scared of protein because it raises their blood glucose. They do seem okay with the protein shakes though.
This is because most protein shakes are everything but. Shakes labeled as "protein", found at the supermarket, are really just carb laden smoothie desserts. Unless the person is actually consuming good quality whey protein, that contains no added sugar or fillers, they aren't really supplementing protein seriously. They are supplementing sugar, regardless of whether the shake actually contains it or not. This is why they like drinking shakes but not eating steaks.
Unfortunately, because of the internet, a lot of these people are going around with their little blood glucose meters chasing their symptoms so when they see their blood glucose rise after protein intake, they start panicking as they don't understand what's happening. It's a shame but all you can do is try to explain to them what's going on and emphasize the importance of protein. Since you have been reading my blog, you understand how to do just that.
6. How can I stop my clients from eating so much fat? They seem scared to eat any other macronutrient.
You won't be able to stop them. Like the question above, there are a lot of symptom-chasing people, who don't understand what's happening to them. They only see what their blood glucose meter reads, and their blood glucose barely budges when they eat fat. For them, this is a "miracle", of some sort, since they have no clue how metabolism works. They will continue to insist on eating fat because of this and eventually their diabetes will worsen with time and their weight will continue going up.