Their estimate of brain calorie consumption is way low, in comparison with other studies.  Will have to check out that linked article.

From that article:

Although the average adult human brain weighs about 1.4 kilograms, only 2 percent of total body weight, it demands 20 percent of our resting metabolic rate (RMR)—the total amount of energy our bodies expend in one very lazy day of no activity. RMR varies from person to person depending on age, gender, size and health. If we assume an average resting metabolic rate of 1,300 calories, then the brain consumes 260 of those calories just to keep things in order. That's 10.8 calories every hour or 0.18 calories each minute. (For comparison's sake, see Harvard's table of calories burned during different activities). 

Read more:

https://www.scientificamerican.com/article/thinking-hard-calories/

This quote:

Randi Zuckerberg called it the entrepreneur's dilemma: "Maintaining friendships. Building a great company. Spending time w/family. Staying fit. Getting sleep. Pick 3.” To be successful, you must make sacrifices. Big ones.