Percentage of paroles granted by Israeli judges, circles are cases immediately following food breaks:
The decisions you make when you're well-fed are more likely to weigh the nuances of the matter, take positive risks, and avoid the "default" choice. Making complex judgments rapidly depletes the brain's energy stores, and as blood sugar declines, people make progressively more default-driven choices. It isn't pessimism, it's unwillingness to take the tougher choice. Good salespeople and other social engineers use this fact against you: they force you to make a series of unimportant decisions, then once you're experiencing decision fatigue, hit you with the big choices and present the more expensive option as the default. Depleted willpower biases people to make bad decisions.
The chart of the judges' decisions should alarm you. This is a group of highly-experienced, super-deliberative experts, making judgment calls in matters of great importance (sometimes life or death), and the strongest predictor of outcome is how hungry the judges are.
Decision order is more strongly correlated with granting parole than time served, and arguably as important as repeat offenses:
Thankfully, some studies have shown that a snack break can reverse or reduce the decline in cognitive decision-making capacity. Always keep small, healthy snacks with a little sugar in them on hand when you're working hard on tasks requiring focus and judgment. (This does not mean energy drinks, those will cause you to peak and crash.) Other types of breaks also help a lot, but blood sugar specifically seems to have a measurable impact. Snack breaks replenish your willpower.
[Note: Followup studies have raised some confounding factors in this specific example, such as parole lawyers front-loading the docket with more promising cases. But the point about blood sugar impacting willpower is legitimate.]