If these extended periods without delicious food sound too painful to handle, rest assured: The best available evidence indicates that a regular ol’ diet is at least as safe and healthy and efficacious as intermittent fasting. Besides, sooner or later, a shiny new fad is bound to come along for the A-listers to fawn over, she says: “There’s going to be a new darling of the month before you know it.”
Now I'm certainly not linking the devil to a piece of pie, but I am saying this: the devil will always call your attention repeatedly to the thing that is harmful for you, but he will do it in a way that makes you feel deprived if you don't indulge in eating, drinking, or partaking of what is harmful. The implication of the devil is always: "This is so good. Has God really said you can't have any of this good thing?"
One type of ketone flooding the brain is beta-hydroxybutyrate, or BHB. According to a paper published in February in Nature Reviews Neuroscience, BHB stimulates memory, learning and the cellular housekeeping process of autophagy in mice. BHB also triggers neurons, including those in the hippocampus, a memory center in the brain, to release what’s called brain-derived neurotrophic factor, or BDNF, a protein that is important for learning, memory and improved mood. CR doesn’t generate these levels of ketones because glucose stores are never empty.
Third, you've probably already fasted many times, even though you don't know it. Have you ever slept in late on the weekends and then had a late brunch? Some people do this every weekend. In situations like these, we often eat dinner the night before and then don't eat until 11am or noon or even later. There's your 16–hour fast and you didn't even think about it.
John Calvin, the figurehead of the Reformed tradition (the Continental Reformed, Congregational, Presbyterian, and Anglican Churches) held that communal fasts "would help assuage the wrath of God, thus combating the ravages of plague, famine and war." In additional, individual fasting was beneficial in that "in preparing the individual privately for prayer, as well as promoting humility, the confession of guilt, gratitude for God's grace and, of course, discipling lust." As such, many of the Churches in the Reformed tradition retained the Lenten fast in its entirety. The Reformed Church in America describes the first day of Lent, Ash Wednesday, as a day "focused on prayer, fasting, and repentance" and considers fasting a focus of the whole Lenten season, as demonstrated in the "Invitation to Observe a Lenten Discipline", found in the Reformed liturgy for the Ash Wednesday service, which is read by the presider:
The Bible also gives instructions about the attitude and approach we should have in fasting. Jesus warned about hypocritical fasting, trying to show off or make others feel sorry for us (Matthew 6:16-17). Instead we should not “appear to men to be fasting, but to your Father who is in the secret place” (verse 18). Isaiah also contrasts selfish fasting with godly fasting marked by care and concern for others (Isaiah 58:3-10).
Fasting or intermittent calorie restriction may affect cancer and tumor development, but are not currently used as a form of treating cancer. In 2011, the American Cancer Society recommended that people undergoing chemotherapy increase their intake of protein and calories, but provided evidence that a short-term period of fasting may have benefits during chemotherapy. Chronic fasting is not recommended for people with cancer at risk for weight loss or a suppressed immune system.