I found a really nice study:
https://academic.oup.com/jn/article/128/1/50/4728756
“From our results, a recommendation not to exclude palatable high fat foods at the high and extreme altitude camps can be made for future expeditions. Inclusion of such items would allow the climbers to self-select energy-dense foods along with the easily prepared, high carbohydrate foods needed for endurance. Items such as cheese, canned fish in oil, retort sausages, and chocolate bars, among others, meet these criteria for the high fat foods. Provision and modest consumption of such energy-dense foods may help provide the extra energy necessary to ensure climbing success and, perhaps, survival.”