I promise you, that was the actual diet – intended keto or not. Absolutely nothing that even looked like a starchy food or if it contained sugar. No potatoes, carrots, rice, mashed potatoes, sweets, etc. Maybe some fruit but fruit was not a big part of our meals. Milk and water only. Lots of meats and greens and that was about it. SOME beans or peas might have been allowed. Now this was the 1960s before high fructose corn syrup caught on and the government began recommending high carb eating. So it is natural that the Marine Corps would look back to the old dietary ways of our grandparents … cut back on the sweets, whites and snacks.
To prove the point, the recruits that they wanted to bulk up were put on a “skinnies” diet and damn near force fed carbs and sweets. These guys seemed to be almost as miserable as us and certainly had more stomach upset, visibly so. I guess the Corps diet wasn’t perfect for them. But they did bulk up.
Footnote: The Corps wasn’t totally heartless in their diet approach. On Nov. 10, while I was in boot camp, the Marine Corps celebrated its birthday. A glorious day of dispensation and feast. Even the “hogs” were allowed one slice of birthday cake and one cup of sweet Kool-Aid! Damn, it tasted good.