Seven Fat Years, Seven Lean

The Season

February is the lean end of winter, when northern larders ran low, and in 2027 it holds the start of two great fasts: Ramadan begins around 8 February (by moon sighting) and Lent on Ash Wednesday, 10 February. The month asks the question this hallmark asks: what is the fast for, and what does it make room for?

The Biology

Every cell keeps a running estimate of how much food is around. Four signalling systems do the reckoning: insulin and IGF-1 announce plenty, mTOR turns plenty into growth, AMPK sounds the alarm when energy runs low, and the sirtuins track the cell's energy state through NAD+. In youth these sensors swing between feast and fast. With age, and with constant eating, sitting still and short sleep, they settle into a permanent "fed" setting. Insulin sensitivity falls, mTOR stays switched on, and the repair work that belongs to lean hours (autophagy, mitochondrial renewal) gets done less often. Lowering these signals lengthens life in worms, flies and mice. In humans the evidence is about rhythm rather than scarcity: movement, muscle, sleep and meal timing restore the swing.

Anchor facts

• In the Diabetes Prevention Program, a lifestyle programme of modest weight loss and 150 minutes a week of activity cut progression to type 2 diabetes by 58%, against 31% for metformin. Source ↗
• Two years of about 12% calorie restriction in healthy non-obese adults (CALERIE) slowed one DNA-methylation measure of the pace of ageing, DunedinPACE, by about 2–3%, while two other clocks did not move. Source ↗
• Unlike in rodents, long-term calorie restriction did not lower IGF-1 in humans; moderate protein restriction did. Source ↗

The Canon

• Genesis 41 (KJV, 1611) — Joseph reads Pharaoh's dream of seven fat and seven lean kine, 41:1–36. "And that food shall be for store to the land against the seven years of famine" (41:36). The storehouse is the insulin signal, putting abundance aside, and the passage turns on the difference between wise storage and a surplus that swallows everything. The lean kine eat the fat and are "still ill favoured" (41:21): plenty that does not register is the insulin-resistant state.
• Franz Kafka — "A Hunger Artist" (1922) — the whole story, especially the ending, where the dying artist confesses he fasted only because he never found the food he liked, and a young panther takes his cage. The warning against making restriction the goal: the artist fasts without pulsatility or purpose, and wastes away. Plain vitality (the panther) replaces him.
• Charles Dickens — Oliver Twist (1838), chapter 2 — the workhouse gruel scene. "Please, sir, I want some more." Imposed deprivation is not calorie restriction: malnutrition and fear sit at the opposite pole from the chosen, nourished restraint of CALERIE. The scene helps separate hunger that harms from hunger that renews.
• John Milton — Paradise Lost, Book IX (1667), lines 791–792 — "Greedily she ingorg'd without restraint, / And knew not eating Death." Appetite without a signal to stop, where eating itself becomes the mortal act: the most exact literary image of a nutrient sensor stuck at "more".
• Isaiah 58 (KJV) — "Is not this the fast that I have chosen? to loose the bands of wickedness" (58:6). The prophet reframes fasting as release rather than self-punishment, much as the protocol treats the fast as a signal (AMPK, repair) and not as a virtue in itself.