I guess it's the sugar/carb rush and then crash which happens to a lot of people, like after a Thanksgiving meal. Even though turkey or other meat has protein, we may also be eating mashed potatoes and gravy, yams and marshmallows, a couple of desserts - all of which are carbs that will make us crash.
Here are some sites that explain this better than I can and each has some different information. I think the key is the amount of protein along with the rest of the food eaten:lifehacker.com/5809331/what-sugar-actually-does-to-your-brain-and-bodylifehacker.com/5866700/why-sugar-makes-you-tired-and-what-you-can-do-about-itwww.wired.com/2011/12/why-sugar-makes-us-sleepy-and-protein-wakes-us-up/
Doesn't Dr. Pepper have a lot of caffeine? Maybe that kept you up?
Trying to strike a balance with what to eat and drink can drive you crazy! lol
Laniediabetes moderatordiabetes type 2 controlled by diet and exercise and
very low carb way of eating