Sleeping and spending a couple days at elevation before your summit bid is the best strategy for acclimatizing when hiking Whitney. Horseshoe Meadows is not too far from Whitney Portal and it sits right around 10,000 feet. Stay a couple days there. I have a video documenting all this - I'll post at the bottom. You can also do some hikes up to New Army Pass or Cottonwood Pass out of Horseshoe Meadows. These passes sit at an elevation similar to Trail Camp. Make sure to drink lots of water while you are acclimatizing.
As for calories, I wouldn't just eat calorie dense foods like pizza the day before - which fat, obviously being the higher in calorie out of the macronutrients (1g of fat equals 9 kcals). Fat also takes longer to digest, especially at higher altitudes. Eat the fat and protein after the hike - not before! Mt Whitney main trail is all up hill and you will need to fill up your muscle glycogen to have enough energy to hike. Hikers that do not do this often run into trouble with low energy. Then as they reach 12k in elevation, they run into hypoxia issues (just like you described) making it even harder to get food down. You'll want to do a specific carb-loading pattern designed for your body a couple days leading to your hike. I do not know your physical condition or daily energy expenditure needs, so I'll show you what I do the days leading before Whitney or any long day peakbagging. 2 days out I increase my daily carbohydrates to 100grams. One day out, I double my daily carbohydrate intake (usually this puts me around 400g of carbs), I lower my fat intake on these days as well. Protein remains the same. The day of the hike sometimes I'll eat breakfast or I'll wait until I have hiked around 5 miles - all depends how I feel. When hiking, I mainly eat 200 kcals of carbs every hour or two. Again, this can vary depending how my body feels. Ever since I have incorporated these strategies (years ago), I have had no issues with maintaining my energy when hiking long days. You will have to experiment with your body to see how it responds. For example, I am engaged in consistent resistance training as well as cardio training. I hold more muscle mass than the average hiker. So, I have to eat more carbs (and calories) for my energy needs.
I do hold degrees in both nutritional science and kinesiology. Also, I do this for a living too (clinical/research work). I love helping people - just so no one thinks I am giving made up advice - "bro science" LOL!
I hope you have great success on your next Whitney hike!
Here is the video documenting Whitney trail and acclimatizing to high elevations:
https://youtu.be/nqE-Od-cvyk
