I'm going to preface this by saying that I'm going to be adding some addendums/emphasis and providing some additional context for some things about her condition in here. I do not mean any of this to say that I believe that you personally are or plan on discounting her condition. It is meant only for emphasis because the particular bariatric surgery she had, the Duodenal Switch is significantly more involved than most other surgeries. A lot of people end up having to have the surgery partially reversed because they can't keep up with the vitamin supplementation and end up hospitalized and dying of malnutrition.

The malabsorption means that she already has to have many small meals through the day. Then each of those meals needs to hit certain macros while being under that volume.

So like to give an example. She needs at least 200g of protein in a day while staying as far under 50g of carbs as possible (fiber included) to not be utterly miserable. That's not "the doctor told me to get this much" they told her to go for 150g. That's the levels she's found over the years result in her not being in significant gastrointestinal distress and actually having decent energy levels along with the roughly 50 vitamin supplements she HAS TO TAKE TO NOT DIE OF MALNUTRITION because and I cannot stress this enough the malabsorption means she CANNOT properly absorb most of these vitamins from food. They need to be very specific formulations at specific times of day to keep her levels up. Like 125,000IU+ PER DAY of Vitamin A (This is WILL KILL YOU levels for a normal person BTW) to still be partially night blind from deficiency (yes she has seen a doctor about it to make sure it's nothing else)

That 1.5 cups of black beans is around 22.5g of protein and 60g of carbs. So that's 2 entire "meals" of nothing but beans to have a little over 1/10th of the protein she needs in a day and 20% over the entire day's limit for carbs.